• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 Table of Contents
 Abstract
 Introduction
 Blue compact galaxies
 The data
 Analysis of the data
 Conclusions
 Bibliography
 Biographical sketch














Group Title: neutral hydrogen survey of blue compact galaxies
Title: A neutral hydrogen survey of blue compact galaxies
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Permanent Link: http://ufdc.ufl.edu/UF00099520/00001
 Material Information
Title: A neutral hydrogen survey of blue compact galaxies
Physical Description: vii, 148 leaves : ill. ; 28 cm.
Language: English
Creator: Gordon, David, 1950-
Publication Date: 1979
Copyright Date: 1979
 Subjects
Subject: Interstellar hydrogen   ( lcsh )
Galaxies   ( lcsh )
Astronomy thesis Ph. D   ( lcsh )
Dissertations, Academic -- Astronomy -- UF   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by David Gordon.
Thesis: Thesis--University of Florida.
Bibliography: Bibliography: leaves 144-147.
General Note: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00099520
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000097448
oclc - 06566571
notis - AAL2888

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Table of Contents
    Title Page
        Page i
        Page ii
    Acknowledgement
        Page iii
        Page iv
    Table of Contents
        Page v
    Abstract
        Page vi
        Page vii
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
    Blue compact galaxies
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
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        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
    The data
        Page 36
        Page 37
        Page 38
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        Page 67
        Page 68
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        Page 70
        Page 71
        Page 72
    Analysis of the data
        Page 73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
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        Page 136
        Page 137
    Conclusions
        Page 138
        Page 139
        Page 140
        Page 141
        Page 142
        Page 143
    Bibliography
        Page 144
        Page 145
        Page 146
        Page 147
    Biographical sketch
        Page 148
        Page 149
        Page 150
        Page 151
Full Text













A NEUTRAL HYDROGEN SURVEY
OF BLUE COMPACT GALAXIES











BY

DAVID GORDON


















A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE
UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY



UNIVERSITY OF FLORIDA





























To My Parents,

Dora Denby Gordon

and

Maurice Gordon















ACKNOWLEDGEMENTS


I wish to express my appreciation to Dr. Stephen T. Gottesman, who

introduced me to the field of extragalactic neutral hydrogen studies.

It was his suggestions and ideas which led to this study. His ex-

perience and his suggestions, comments and encouragement have been

invaluable in the HI observations and in the analysis of the data.

Many others deserve mention here. At the National Radio Astronomy

Observatory, Dr. Richard Fisher and Dr. Patrick Crane were most helpful

in making observations with the 91 meter telescope. I am grateful to

the many telescope operators and engineers who helped make the observa-

tions a success and to Al Wu, in particular, who did an excellent job

of maintaining the receiver system.

I am also grateful to the many telescope operators and engineers

at Arecibo Observatory for performing an excellent job. I particularly

wish to thank Dr. Edward K. Conklin and Dr. Michael M. Davis for their

expert assistance in making the spectral line observations on the 305

meter telescope. Special thanks are due to Dr. Nathan A. Krumm for

his invaluable help in reducing the observations at Arecibo Observatory

in 1977. Special thanks must also be extended to Dr. Martha P. Haynes,

who provided computer programs which allowed me to read and reduce the

1978 Arecibo data tapes at the University of Florida.

Special thanks are also extended to Dr. Gerard de Vaucouleurs and

Dr. Harold G. Corwin for calculating blue magnitudes from Zwicky









photographic magnitudes for several dozen galaxies. Without their help,

the luminosities of many systems could not have been determined as

accurately as they were.

Further thanks are extended to Dr. Michael D. Desch and Mr. David R.

Florkowski for help in miscellaneous areas, inspiration, and many

interesting discussions.
















TABLE OF CONTENTS


CHAPTER PAGE

ACKNOWLEDGEMENTS . . . . . . . . . iii

ABSTRACT . . . . . . . . ... . . vi

I INTRODUCTION . . . . . . . . ... . 1

II BLUE COMPACT GALAXIES. . . . . . . . . 8

III THE OBSERVATIONS . . . . . . . . ... .16

The 21 cm Line . . . . . . . . ... .16
21 cm Spectral Line Observations . . . ... 19
Observations on the 91 Meter Telescope ...... 22
Observations on the 305 Meter Telescope. . . ... 28

IV THE DATA . . . . . . . . ... .. . .36

Optical Parameters . . . . . . .... .36
21 cm Global Parameters. . . . . . . ... 50

V ANALYSIS OF THE DATA . . . . . . .... .73

Selection Effects and Completeness of the Sample . 74
Luminosities . . . . . . .... . .. 79
Neutral Hydrogen Content . . . . . .... 88
HI Dimensions. . . . . . . . . ... 90
The HI Profiles. . . . . . . . . ... 100
Total Indicative Masses. . . . . . . ... 115
Comparisons Between Color, HI Mass, Luminosity and
Indicative Mass ............... 118
Comparison With Low Surface Brightness Systems . 132
Correlations . . . . . . . . . . 134

VI CONCLUSIONS. . . . . . . . . . ... 138

Suggestions for Future Study ...... .... 142

BIBLIOGRAPHY . . . . . . . . . . 144

BIOGRAPHICAL SKETCH. .. . . . . . . . 148















Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy


A NEUTRAL HYDROGEN SURVEY
OF BLUE COMPACT GALAXIES

By

David Gordon

December, 1979

Chairman: Stephen T. Gottesman
Major Department: Astronomy

Compact galaxies are galaxies showing high surface brightnesses

and small angular dimensions. They are, morphologically, a very in-

homogeneous group, ranging from featureless objects barely distinguish-

able from stars on plates of the Palomar Sky Survey, to objects showing

various irregularities, such as multiple cores, jets, filaments, bridges

to nearby objects or other irregularities. Most of the compact galaxies

catalogued by Zwicky are red or very red systems. These appear to be

early type galaxies deficient in their outer envelopes. A minority of

the Zwicky compact galaxies, perhaps 10-20%, are blue or very blue.

These appear similar to the compact systems found on the Haro and

Markarian lists of galaxies with strong UV excesses. A fairly common

characteristic of blue compact galaxies is the presence of emission

lines in their spectra, either with or without absorption lines. The

excitation level of the emission in these objects indicates that the

lines originate in HII regions excited by hot young stars. Several








of the objects in this class, mostly dwarf systems, have been found to

be underabundant in elements heavier than helium. Possible explanations

are that these are young galaxies just commencing star formation, or

that they are old galaxies experiencing a brief burst of star formation,

to be followed by a long quiescent period.

This study is a report of the 21 cm neutral hydrogen line observa-

tions of 99 compact galaxies, most of them blue or very blue. Of these,

72 were detected in HI. These systems are found to be richer in HI

than late type galaxies of the Hubble sequence and also to have higher

surface luminosities. Approximately half of these blue compact systems

are bluer than the bluest late type galaxies. Their HI velocity profiles

are often narrow and single peaked, most often for the lower luminosity

systems. However, the evidence suggests that the compact galaxies are

rotating disk systems, perhaps with a strong central concentration of

HI. The observations also indicate that at least some of these systems

are quite extensive in their overall HI dimensions.

It is possible that these HI rich, blue compact galaxies are old

systems which have not yet completed their collapse out of the inter-

galactic medium. Primordial gas may be condensing into their central

regions and could be the source of gas for intermittent, brief bursts

of star formation.














CHAPTER I
INTRODUCTION


In addition to the many normal types of galaxies which fit nicely

into the Hubble sequence of galaxies, astronomers now recognize the

existence of various types of galaxies which are described as being in

excited states, or "active." These types of active galaxies are known

mainly under the names of Haro galaxies, Markarian galaxies, compact

galaxies, Seyfert galaxies, N galaxies and quasars (van den Bergh,

1975). There is currently wide discussion as to where, if at all, these

systems belong in the Hubble sequence of galaxies. The following study

is concerned with the compact and high surface brightness galaxies on

the lists by Zwicky, Haro, and Markarian.

Zwicky (1964) defined a compact galaxy as an object of abnormally

high surface brightness just distinguishable from stars on plates taken

with the Mount Palomar 48 inch Schmidt telescope. During the years

1960-1968, while examining the Palomar Sky Survey plates for compilation

of the Catalogue of Galaxies and of Clusters of Galaxies (Zwicky et al.,

1961, 1965; Zwicky and Herzog, 1963, 1966, 1968; Zwicky and Kowal, 1968),

Zwicky produced seven lists of what he called compact galaxies, galaxies

with compact parts, and post-eruptive galaxies. Some 30 years before

this, Zwicky claims to have known of the existence of galaxies with

super-dense stellar populations (described by Zwicky, 1971). He

believed that these compact galaxies were the super-dense stellar

systems he had predicted (Fairall, 1978).








Zwicky distributed his seven lists privately to various astronomers

and later published them in book form. The Catalogue of Selected

Compact Galaxies and of Post-Eruptive Galaxies (Zwicky, 1971) contains

some 2300 systems. Morphologically, these systems make up a very

inhomogeneous group. As seen on the Palomar Sky Survey, many of them

have a small saturated image surrounded by a small amount of

nebulosity, while others show various irregularities, such as jets,

rings, bright knots, distorted spiral arms, multiple nuclei and bridges

to nearby objects. A common feature among these systems is a region or

regions of high surface brightness (Sargent, 1970b). The majority of

these galaxies have normal reddish colors, as seen in E and SO galaxies

and have normal absorption line spectra. A minority, perhaps 10-20%,

are blue or very blue and often have emission lines in their spectra,

indicative that they have regions of ionized hydrogen. The designation

of color by Sargent (1970b) is used here, where a "blue" image is of

approximately equal brightness on both plates of the Palomar Sky

Survey; "very blue" is brighter on the blue plate; "red" is brighter

on the red plate; and "very red" is much brighter on the red plate.

The Markarian galaxies are blue galaxies discovered on objective

prism plates taken with the 1 meter Schmidt telescope of the

Byurakan Observatory by Markarian and his co-workers. They have

published 11 lists so far, containing 1095 galaxies (Markarian, 1967,

1969a, 1969b; Markarian and Lipovetskii, 1971, 1972, 1973, 1974,

1976a, 1976b; Markarian et al., 1977a, 1977b). A 1.50 prism was used,

yielding a dispersion of 2500 Ao/mm at H The aim of their study is

to catalog galaxies with intense ultraviolet continue between apparent

magnitudes 13 and 17.









On these lists, the objects are classified into one of two groups

based on the appearance of their objective prism spectra (Markarian,

1967). Objects having sharp spectra (like stellar spectra) are called

type s. A bright nucleus is the source of their UV continue. Some of

these s types are spiral galaxies with bright nuclei and some are

Seyfert galaxies with broad emission lines arising in their nuclei. In

the second group, type d, the boundaries of the spectra are diffuse,

indicating that the UV continuum originates in an extended region and

not just the nucleus. Intermediate types are designated as types sd or

ds, depending on which type they resemble most. Additionally, a common

characteristic of Markarian galaxies is the presence of narrow emission

lines in their spectra.

Haro (1956) reported on the discovery of 44 blue and very blue

galaxies. These were detected in the course of an objective prism

search for very blue stars, using the Schmidt telescope of the

Tonontzintla Observatory. Like the Markarian galaxies, they show

strong UV excesses. These systems generally fit into the diffuse

(class d or ds) spectroscopic subgroup of the Markarian objects. Like

the Markarian galaxies, emission lines are a fairly common feature of

their spectra.

Many of the Markarian and Haro galaxies are similar to the blue and

very blue high surface brightness compact and post-eruptive systems

listed by Zwicky (1971), in that they are of similar colors, are of

small angular dimensions and have a region or regions of high surface

brightness. Some of these have circular or elliptical shapes like

some of the featureless Zwicky compacts, while others display various

irregularities, such as jets, filaments, multiple cores and other









irregularities. Thus, morphologically, the three groups show many

common properties. The overlap of their properties is further illus-

trated by the fact that of the 99 galaxies reported on in this study,

20 are on both the Markarian and Zwicky lists; 10 are on both the Haro

and Markarian lists; and 2 are on all three lists. Thus, there is

ample reason to group objects from these three lists together in a

study of the properties of blue compact galaxies.

The original definition of compactness (Zwicky, 1964) as being

just distinguishable from stars on plates taken with the 48" Palomar

Schmidt telescope and with diameters of 2-5 arc seconds has proven too

restrictive to be of practical use. This definition has not been

rigorously followed by workers in the field, including Zwicky himself.

Zwicky's (1971) definition of compactness also requires that the

surface brightness be brighter than the 20th magnitude per square arc

second. This requires surface photometry and has not been attempted for

very many compacts. The more or less accepted procedure is to classify

as compact those systems which show, on the Palomar Sky Survey, a small

saturated core, either regular or irregular, surrounded by none or

small amounts of nebulosity, showing no normal structure (such as

spiral arms) but possibly showing irregular structure, such as jets,

filaments, bridges or double cores. This is the definition that is

used in this study to select compact galaxies from the lists of Zwicky,

Haro and Markarian. For the benefit of the reader, we reproduce in

Figure I-1 several examples of compact galaxies. These are negative

prints, taken from the Palomar Sky Survey.

In the following study, we report on neutral hydrogen observations

of 99 compact galaxies. Almost all of these galaxies were blue or very

















Examples of blue compact galaxies taken from the
Palomar Sky Survey.

M7 (= VIIZwl53) has an irregular shaped bright
core surrounded by a small amount of nebulosity.

M297 (= Arp209) has a "hat" shaped core composed
of two bright knots side by side, and a small
amount of nebulosity.

IZw207 is a "boomerang" shaped arc of bright
knots.

IIZw40 is a dwarf blue compact showing a bright,
nearly stellar core and a fainter nebulosity
containing two filaments.

Haro29 (= Izw36 = M209) is a dwarf blue compact
showing two bright condensations, a jet, and a
"fan" shaped nebulosity.

Haro25 (= M727) shows a bright stellar core with
a very small amount of nebulosity and is barely
distinguishable from a star.


Figure I-1.













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7


blue, and thus our discussion will be concentrated on this type. We

shall be concerned with what can be learned from their neutral hydrogen

global properties when considered in conjunction with their known

optical properties. For our discussion and analysis, a Hubble constant

of 75 km/sec/Mpc will be used throughout. A more detailed discussion

of blue compact galaxies follows in Chapter II. In Chapter III, we

describe how the 21 cm spectral line observations were made and reduced.

Optical and neutral hydrogen global data are presented in Chapter IV.

Discussion and analysis of the data are given in Chapter V. Conclusions

and directions for future work are given in Chapter VI.















CHAPTER II
BLUE COMPACT GALAXIES


The lists of Zwicky, Markarian and Haro contain some 3500 galaxies.

The majority of these objects are of small angular dimensions and of

high enough surface brightnesses to be classified as compact galaxies.

The Haro and Markarian compact galaxies are all blue or very blue as a

result of their selection criteria. Zwicky compacts, on the other hand,

cover a wide range of colors--from as red as the reddest Hubble sequence

galaxies to bluer than the bluest type I irregular galaxies. No more

than 20% of these are in the blue or very blue category (Sargent, 1970b).

The objects cataloged by Zwicky (1971) were selected at random,

but they were not chosen in any uniform manner over the entire sky and

are not complete down to any limiting apparent magnitude. The Markarian

lists, on the other hand, appear to be complete down to a limiting

photographic magnitude of mp = 15.5 (Sargent, 1972).

In 1969, Zwicky began a complete survey for compact galaxies on

12 plates taken with the 48" Schmidt telescope (Zwicky, 1971). He

appears not to have completed or published more than a few preliminary

results of this study before his death in 1974. However, Rodgers et al.

(1978) studied the compacts marked on two of these plates. Out of 348

objects marked on one plate, using Sargent's (1970b) color designations,

they found that 232 were very red, 79 were red, 25 were blue and 12 were

very blue. Thus perhaps as few as 10% of the Zwicky compacts are blue

or very blue.








Studies of these red and very red compacts are reported by

Fairall (1971, 1978), Kormendy (1977), Sargent (1970b) and Rodgers

et al. (1978). These systems typically show normal absorption line

spectra typical of early type galaxies. Surface photometry of these

systems indicates that their central surface brightnesses are not so

much higher than is seen in normal early type galaxies (Kormendy, 1977;

Rodgers et al., 1978). Their primary difference from normal E and SO

galaxies seems to be a deficiency in their outer envelopes (Kormendy,

1977; Fairall, 1978; Rodgers et al., 1978). Thus it appears that these

systems do not have the abnormally high stellar densities expected by

Zwicky. Fairall (1978) has suggested that these systems have lost

their outer envelopes as a result of tidal stripping.

We shall now concentrate our discussion on the properties of blue

compact galaxies, with which this study is primarily concerned. DuPuy

(1968, 1970) has studied Haro galaxies. Sargent (1970a, 1972) has

surveyed Markarian galaxies. Sargent (1970b) made a study of Zwicky

compacts which was heavily weighted towards blue objects.

These blue systems are characterized by a strong UV continuum,

colors which are often bluer than the bluest late type galaxies, and

moderate or strong emission lines--typically the Balmer lines and

forbidden lines of oxygen, neon and nitrogen. The emission lines and

the UV continuum are generally concentrated in, but not restricted to,

the nuclear regions. About half of these systems also show absorption

lines typical of the stellar populations in late type galaxies. All 31

Haro galaxies studied by DuPuy (1968, 1970) showed emission lines.

Those brightest in the UV showed the strongest emission lines. Among

the Markarian objects, some 80% seem to show emission lines (Sargent,








1972). Sargent (1970b) found that all Zwicky compact with (U-B)

between +0.20 and -0.15 had both emission and absorption lines and

that all those bluer than (U-B) = -0.15 had emission lines only.

The levels of excitation seen in blue compacts are comparable to

those of galactic HII regions. Thus it is generally agreed that the

emission lines originate in HII regions excited by hot stars. Their

strong UV continue appear to be stellar in nature, the result of a

high number of hot stars (DuPuy, 1970; Sargent, 1970a, 1970b, 1972;

Searle and Sargent, 1972; Forrester, 1973).

The space density of blue, UV intense galaxies has been estimated

by Sargent (1972). For absolute photographic magnitude M between -20

and -22, about 2.5% of all galaxies are UV intense. Their abundance

increases towards lower luminosities. At M = -17, about 7% of all

galaxies are UV intense and at Mp = -14, it may be as high as 10%.

The luminosities of blue compact galaxies cover a broad range. At

the high end, they are as luminous as normal galaxies, and at the low

end, they are as intrinsically faint as the smallest dwarf galaxies.

In the surveys by Sargent (1970b, 1972), the absolute photographic

magnitudes of the Zwicky and Markarian narrow emission line galaxies

were found to extend from -21.6 to -14.9, and from -21.5 to -13.9,

respectively. DuPuy (1970) finds a similar range in the absolute

visual magnitudes of Haro galaxies, from -21.6 to -13.7.

With their broad range of luminosities, blue compact galaxies are

not a homogeneous group. However, the low luminosity dwarf systems may

form a fairly homogeneous subgroup. Sargent (1970b) noted several low

luminosity blue systems fainter than M = -19 among the Zwicky compacts.








Eleven similar dwarf systems fainter than Mp = -16 were identified by

Sargent (1972) from the Markarian lists. Several of the Haro galaxies

also fit into this subgroup. These systems are similar in that they are

all nearly uniformly high in excitation levels, have strong emission

lines relative to their continuum, have physically small emission line

regions,typically a few hundred parsecs across, and are often bluer

than the bluest galaxies of the Hubble sequence (Sargent, 1972). An

exact upper luminosity limit for considering an object a dwarf is not

clearly established. An absolute photographic magnitude of approxi-

mately -17 or -18 appears to be a reasonable upper limit.

Two such blue dwarf compact systems were labelled as "isolated

extragalactic HII regions" by Sargent and Searle (1970). These types

of systems are similar to the largest and highest excitation HII regions

found in the spiral arms of giant late type galaxies, and yet they often

appear as isolated systems. IlZw40 and IZwl8 were studied, using high

resolution spectroscopy. Searle and Sargent (1972) reported on the

abundances found in these two systems. They were found to have normal

and presumably primordial abundances of helium, but significant under-

abundances of heavier elements. IIZw40 and IZwl8 were found to be

underabundant in oxygen and neon by factors of approximately 3 and 7,

respectively, compared to normal HII regions in the solar neighborhood.

(Bergeron (1977), using the same data, gets greater underabundances,

of 6 10 for IIZw40 and 30 50 for IZwl8.) These were the first

metal poor, Population I systems found, raising the question as to

whether they are young galaxies. Obviously they could not have been

producing 0 and B stars at their current observed rates for 1010 years

and have remained metal poor. IIZw40 would have converted approximately








1/4 of its total mass into elements heavier than helium if this were

the case (Searle and Sargent, 1972).

Other examples of metal poor blue dwarf systems have been identi-

fied since. Neugebauer et al. (1976) found that Haro3 (= M35) and

M59 are underabundant in oxygen by a factor of -2 and Haro4 (= M36) is

underabundant by a factor of ~4, with respect to the solar neighbor-

hood. Five additional metal poor systems are found in a study by

Ulrich (1971). Alloin et al. (1978) analyzed spectroscopic data for

these five systems and six others from Sargent and Searle (1970) and

Neugebauer et al. (1976). All 11 of these systems are underabundant

in oxygen, neon and nitrogen. They find oxygen to be underabundant by

factor of ~2 for M19, ~3 for Haro3, -10 for Haro4, ~6 for IIZw40,

-7 for M162, -11 for M193, -6 for M156, -45 for M171, -40 for IZwl8,

-5 for M108 and -5 for M59.

Searle et al. (1973) consider the nature of the bluest galaxies

known--the isolated, metal poor, dwarf blue compacts. These systems

also appear to have a large fraction of their total mass in the form of

HI gas (Searle and Sargent, 1972; Gottesman and Weliachew, 1972). Their

sizes and their stellar and gaseous content are similar to giant HII

regions seen in the spiral arms of giant Sc galaxies. These systems,

which all seem to be bluer than (B-V) = +0.3, are explainable by two

possible hypotheses, according to Searle et al. (1973). Either they are

younger than 10 years, or they are of normal ages (-1010 years) and

have a rate of star formation at this current epoch which greatly

exceeds their past average rate.

Model calculations by Searle et al. (1973) indicate that a

galaxy -2 x 108 years old with a Salpeter initial luminosity function








and a uniform rate of star formation would have the colors of the

bluest dwarf compact galaxies. If these systems are young, and if

their rate of formation has not increased with time, then there should

exist at least 5 times as many 10 years old and at least 50 times

as many 110 years old. The models by Searle et al. (1973) indicate

that such a galaxy would brighten by -0.5 magnitudes in aging from

2 x 108 years to 109 years and by -1.2 magnitudes in aging to 1010

years. Thus old dwarf galaxies should be observationally more abundant

than young, very blue dwarf galaxies by a factor of at least 50 to 100.

As stated earlier, at M = -14, 1 galaxy in 10 appears to be a very

blue dwarf compact (Sargent, 1972). This high an abundance argues

against the young galaxy hypothesis.

In the second hypothesis, called the flashing galaxy or star burst

model, star formation occurs in brief intense bursts. The blue dwarf

compacts are said to be undergoing a burst of star formation equal to

s times their star formation rate averaged over their total lifetime

(Searle et al., 1973). About 1/4 of the light from a galaxy 110 years

old comes from stars no more than 108 years old. Thus a flash of star

formation of strength s = 4 or more would have profound effects on the

colors of a galaxy. The colors of the bluest galaxies would require

flashes of strength s = 10 20 to produce. Such a flash would increase

the luminosity by 1 2 magnitudes and would require -3 x 108 years for

the color and luminosity to return to normal. Searle et al. (1973)

propose that the blue dwarfs have ages of -1010 years and have under-

gone perhaps 5 10 brief bursts of rapid star formation, each lasting

-108 years. Nonflashing galaxies of this type should have a space

density -2 5 times those of the very blue dwarfs. Flashing galaxies









will be brightest during and just after a flash, so at a given absolute

magnitude, the ratio of interflashing to flashing galaxies will be

fairly low, perhaps as low as 1.

Searle et al. (1973) conclude that extremely blue galaxies of

high luminosity must be very rare. They consider a galaxy as composed

of statistically independent cells in which star formation is either not

occurring or is occurring in a burst. They use a cell size approxi-

mately equal to the smallest blue dwarfs, or M = -14. Thus a galaxy

of M = -19 has 100 such cells. They calculate the probability of at

least half of the cells in a galaxy undergoing flashes at any given

time. These probabilities are 0.16 at Mp = -15, .02 at Mp = -16 and

10-4 at M = 17. Thus extremely blue galaxies brighter than M = -17

should be extremely rare, according to this model.

Nondwarf blue compact systems have not received as much attention

as the blue dwarf systems. These galaxies are similar in size and

luminosity to late type Hubble sequence galaxies, but they do not show

any obvious spiral structure. Some of these systems do show hints of

spiral structure on direct plates more sensitive and with a greater

plate scale than the Palomar Sky Survey (Fairall, 1978).

O'Connell and Kraft (1972) obtained a rotation curve of IZw129, a

blue luminous compact galaxy with a bright central core and a faint fila-

mentary structure. Its absolute visual magnitude is -21.1. They find

clear evidence for rotation and calculate the total mass interior to

the last point of their rotation curve. The mass determined for this

system is quite low compared to its luminosity.

O'Connell (1979) studied nine nondwarf blue compacts, all brighter

than M = -19. Slit spectra were taken of these systems. Some








internal structure was seen in their HII distribution, such as evidence

of ring-like or of one-armed spiral structure. Good rotation curves

were obtained for six of these systems. The remaining three showed

no evidence of rotation. Two of these were face-on while the third,

IVZw153, was a double system and needs more study. The rotation curves

for the six systems were found to be consistent with circular motion.

These rotation curves resemble those of Sc and Sd galaxies. Unfortu-

nately, only one can be traced to a velocity turnover point. The total

mass-to-luminosity ratios for these six systems averages to -1.2

(scaled to a Hubble constant of 75) within the regions observed. This

is about 1/3 of the values typically found in the interiors of late

type spirals.

Neutral hydrogen studies of blue compact galaxies have generally

been quite successful. Bottinelli et al. (1973) detected at least nine

Haro galaxies in HI with the Nancay radio telescope. The HI masses

found were large compared to their total luminosities and estimated

total masses. Markarian galaxies also were found to be rich in HI by

Bottinelli et al. (1975). Blue Zwicky compacts showing emission lines

were shown to HI rich as well (Chamaraux, 1977).

Gottesman and Weliachew (1972) made a low resolution, aperture

synthesis study of the HI in IIZw40. It was found to be very extensive

in HI. This object has an HI core approximately equal in size to its

optical halo and an HI halo approximately six times larger than this.

Approximately half of its HI mass is in this HI halo. They found non-

conclusive evidence of rotation and were able to estimate a lower

limit to the total mass. The total mass is found to be at least twice

the HI mass (adjusted to a Hubble constant of 75).















CHAPTER III
THE OBSERVATIONS


Observations of the 21 cm line of neutral atomic hydrogen were made

using the 91 meter (300 foot) radio telescope of the National Radio

Astronomy Observatory (NRAO) in Green Bank, West Virginia, and the

305 meter (1000 foot) radio telescope of Arecibo Observatory, near

Arecibo, Puerto Rico. The NRAO is operated by Associated Universities,

Inc., under contract with the National Science Foundation. The Arecibo

Observatory is part of the National Astronomy and Ionosphere Center,

which is operated by Cornell University under contract with the National

Science Foundation. A discussion of the 21 cm emission line and how

the observations were made follows in this chapter.


The 21 cm Line


A discussion of the nature of the 21 cm emission line is given by

Kerr (1968). The ground state of atomic hydrogen is split into two

hyperfine sublevels, the upper state being metastable. In the lower

energy state, the magnetic dipole moments, or spins, of the proton

and the electron are in opposite directions, or antiparallel. In the

higher energy state, the two spins are parallel. The difference in

energy between these two states corresponds to the energy of a photon

of wavelength 21.11 cm and frequency 1420.4058 MHz. The emission or

absorption of a 21 cm photon is produced by a transition between these

two energy levels, often called a spin flip transition.









For an HI region in thermodynamic equilibrium, the relative popula-

tion of the lower and upper levels, no and n1, respectively, is given

by the Boltzmann equation,


n, 91 -hv
= exp(- ), III-1
n0 g0 kTs


where k is Boltzmann's constant, h is Planck's constant, Ts is known as

the spin temperature and v is the frequency, 1420.4058 MHz. The

statistical weights of the lower and the upper energy levels, g0 and gl,

are given by gi = 2Fi + 1, where Fi is the sum of the spin of the

electron (1/2) and the proton (+1/2). Thus F0 = 0, F1 = 1, g0 = 1

and g1 = 3. The term (hv/k) = 0.07 K and will always be much less than

the spin temperature. Thus, exp(-hv/kTs) will always be close to unity.

For example, at Ts = 10 K, nl/n0 = 2.9806; at Ts = 100 K, nl/n0 = 2.9981;

and at Ts = 1000 K, n /n0 = 2.9998. Thus about 3/4 of the HI atoms in

a galaxy's interstellar medium will be in the upper ground state at all

times. This means that it is not necessary to know the spin temperature

of an HI region in order to determine the number of neutral hydrogen

atoms present.

The Einstein coefficient, A21, for the 21 cm spin flip transition

is 2.85 x 10-15 sec-1. Thus the radiative lifetime of the upper level

is very long, approximately 1.1 x 107 years. In the interstellar

medium of a galaxy, the time between collisions will be much shorter

than this, so that most transitions will be due to collisions. A

typical HI atom will move up and down between the two levels about

every 400 years due to collisions, but only about every 11 million

years will it undergo a spontaneous downward transition with the









emission of a 21 cm photon. If collisions are dominant in populating

the two levels, then the spin temperature will effectively be equal to

the kinetic temperature.

The equation of transfer can be solved for the brightness

temperature, TB, of an HI region. One gets


TB = Ts (1 e-) III-2


where T is the optical depth of the HI region. It is generally

believed that the optical depth in HI regions is small. Thus

equation III-2 reduces to


TB TTs 11I-3


Assuming small optical depth, the total number, NH, of hydrogen

atoms per cm2 along the line of sight is



NH = 3.88 x 1017 f_ TB d III-r



where v is in KHz. However, HI spectra are normally plotted as a

function of velocity, v, in km/sec. The number of hydrogen atoms per

cm2 along the line of sight is then



NH = 1.823 x 1018 1 T *dv III-5



Flux, rather than brightness temperature, is the observed quantity

in radio astronomy observations. Equation III-5 can be reduced to the

total neutral hydrogen mass by








MHI = 2.356 x 105 D S -dv, III-6



where MHI is the HI mass in units of solar masses, S is the flux in

Janskys, and D is the distance to the HI region in Mpc. The integral

need only be evaluated over the velocity range of the HI region and will

simply be the area under the HI profile, if it is plotted in the usual

units of Janskys versus km/sec.


21 cm Spectral Line Observations


For the type of radio telescope considered here, the desired signal

from an astronomical source is focused by a reflector onto the front end

of a radio frequency (RF) receiver, known as the antenna, or feed,

mounted at the focus of the reflector. For 21 cm observations, the re-

ceiver is designed to receive both orthogonal polarizations, and to have

its maximum sensitivity at or near the expected Doppler frequency of

the spectral line. The RF signal from the feed is combined with a

local oscillator (LO) frequency to produce a lower, intermediate fre-

quency (IF) signal. In spectral line observations, the LO must be

computer controlled to correct for the constantly changing motion of

the earth. The IF power is passed into a baseband mixer and

then into an autocorrelator which produces the spectrum.

An autocorrelator works in arbitrary units. In order to determine

the total amplitude of the signal, the system temperature, Tsys, must

be determined independently of the autocorrelator. This is done by

monitoring the total IF power and comparing it to a source of known

noise temperature. The power from the noise source, of noise tempera-

ture TN, is periodically injected into the receiver. Continuum








receivers measure the power when the noise source is on, P on' and

when it is off, Poff* The system temperature is given by

(Pon+ Poff )
sys 2(Pon Poff) -7

The total bandwidth B is fed into the autocorrelator, which uses

N channels per polarization. Each channel has a time delay of n -At,

where n is the channel number (from 1 to N) and At = 1/2 B. The auto-

correlator computes the autocorrelation function, ACF(n At), of the

spectral bandpass. The spectral bandpass can be considered to be a

function of time, y(t). Then the autocorrelation function is

T
ACF(n At) = limit 1 T y(t) -y(t +n -At). II-8
2

Each channel of the autocorrelator gives one point of the autocorrela-

tion function. The power spectrum is obtained by taking the Fourier

transform of this autocorrelation function, usually by an on-line

computer. The result is an N channel spectra of total bandwidth B.

The channels will be spaced B/N apart and each channel will have a half

power width, or resolution, of Af = 1.21 B/N (Shalloway et al., 1968).

This spectrum is not in a readily usable form. The channel values

are scaled arbitrarily; the bandpass is not smooth or flat; and the

bandpass is usually dominated by the system noise temperature. For these

reasons, 21 cm spectral line observations of external galaxies are

usually made in what is called the "total power" mode. In this scheme,

an "ON" spectrum is taken at the position of the source, and an "OFF"

spectrum is taken at a blank sky position. The OFF spectrum will be the









receiver passband function, while the ON spectrum will be the receiver

passband function plus the source signal. Let ON(i) and OFF(i) be the

relative intensities in the ith channel of the ON and the OFF spectra,

respectively. Then the antenna temperature, T(i), of the source in

channel i is


T(i) = ON(i) OFF(i)
T(i) OFF(i) sys 111-9



In practice, it is necessary to get a good match between the ON and

the OFF spectra. This is usually accomplished by using the same

integration time and center frequency and by following the same range

of altitude and azimuth in the sky so that any instrumental effects

will be repeated in both the ON and the OFF spectra. The two should

also be taken closely together in time to avoid slow changes in the

gain of the receiver.

The system sensitivity will be the RMS noise temperature, ATrms

given by

y'T
AT sys T III-10
rms Af-t


where t is the total integration time and y is a constant (21) which

depends on the system and how it is operated.

The RMS flux is given by


2k' ATr
AS rms III-11
rms Ae
e








where Ae is the effective area of the reflecting dish, typically

50-60% of its geometric area. In practice, the minimum detectable flux

is about three times the RMS flux.


Observations on the 91 Meter Telescope


The 91 meter (300 foot) diameter telescope of the NRAO is located

in the mountains of West Virginia, near the town of Green Bank. Its

parabolic reflecting surface is an aluminum mesh which is effectively

a solid reflector at radio wavelengths down to about 6 cm. Being

solely a transit telescope, it points always at the meridian and is

movable in declination between the North Celestial Pole and -19

declination. The front end of the 21 cm receiver is located at the

focus on a travelling mount which allows the feed to be moved up to

1/2 degree to the east and to the west of the meridian. This allows

a transiting source to be tracked for 4 sec 6 minutes ( =

declination).

The orthogonal linear polarizations are fed into cooled parametric

amplifier receivers, giving system temperatures of typically 50 K in

each polarization. A bandwidth of 10 MHz was used for all the observa-

tions. The spectra were produced with the NRAO Mark III autocorrelation

receiver (described by Shalloway et al., 1968). This is a one bit

digital machine containing 384 channels. Thus 192 channels were used

for each polarization. The channel spacing was approximately 11.1 km/sec

and the channel resolution was approximately 13.4 km/sec. Employing

this system, the constant y in equation III-10 is approximately 1.6.

For each source, an OFF scan was usually taken first, selected to

end 70 seconds before the ON scan was to begin. This allowed time to








move the feed back to its starting position before beginning the ON

scan. Both the ON and the OFF scan were of the same duration and

covered the same range in altitude and azimuth. The autocorrelator

was set to integrate for 20 seconds. Each of these 20 second spectra

is called a "record." All the records taken during a single transit

are called a "scan." These individual records were initially recorded

on a 7-track magnetic tape. All the records in each scan were daily

averaged together by the computer staff in Charlottesville, Virginia,

and written onto a 9-track tape.

We received 8 days of observing time in March 1977 and 12 days in

September 1977. The sources were observed each transit, excluding

periods when the telescope was shut down for maintenance and malfunc-

tions. Most of the sources were observed for at least 5 transits and

several were observed for as many as 20 transits.

For proper calibration of the system, drift scans of 21 continuum

sources were taken at various times during gaps in the observing

schedule. Only unconfused sources from Bridle et al. (1972) were

used. A drift scan consisted of setting the telescope at the meridian

and at the declination of the calibration source several minutes before

transit and allowing the source to drift through the beam of the tele-

scope. The noise tubes were fired just before and after the source

drifted through the beam. The signal due to the noise tubes and the

source were recorded as deflections on a strip chart. Since the

temperature of the noise tubes and the flux strength of the calibration

sources were known, the sensitivity of the system in Jy/K could be

found. The results of all drifts in both polarizations were averaged

together. The final results for the 21 calibration sources are








presented in Table III-1. Column (1) gives the name of the calibration

source. Column (2) gives the 1950 declination. Column (3) gives the

sensitivity of the system in Jy/K. Column (4) gives the number of

drift scans used. Column (5) is the flux of the calibration source in

Janskys at 1400 MHz, from Bridle et al. (1972). The sensitivity was

found to be a fairly smooth function of the declination. A parabola

has been fit, by the method of least squares, relating the sensitivity

of the system S, in Jy/K, to the declination 6, in degrees. This

parabola is given by


S = 0.99775 0.004408 + 0.0000749 62 III-12


The RMS uncertainty is 0.02 Jy/K, or about 2%. The data points and

the parabolic fit are shown in Figure III-1.

The reason for this declination dependency is presumably due to

deformation of the parabolic reflector. The calibration curve is not

centered on the zenith as expected. Greatest sensitivity occurs at

approximately +290 declination, whereas the zenith is at approximately

+380. This calibration curve agrees quite well with one obtained for

the 91 meter telescope by Fisher and Tully (1975). However, their

calibration curve reaches its maximum sensitivity very near the zenith.

A small correction was also required for the variation of sensi-

tivity with hour angle. When east or west of the meridian, the para-

bolic reflector is used off axis, resulting in decreased efficiency.

Several continuum sources were tracked and the average flux was found

to be approximately 4.5% less than the peak flux at the meridian. Thus,

in the final analysis, all spectral intensities were multiplied by

1.045.

















Table III-1.



Source

(1)
P2128-12
3C422
3C C8
3C 132
3C234
3C48
3C21 7
3C197. 1
3C1 47
3C325
3C371
aC-02. 79
DWL 716 *00
3C435
3CA49
3C0
PK 0 11 +19
3C2;86
3C131
4C33.48
3C351


Sources Used for Calibrating the
91 Meter Telescope.


Dec Jy/K


(2)
-12 2C
-2 47
10 18
22 45
29 2
32 54
38 1
47 12
49 50
62 50
69 4C
-2 32
0 40
7 20
13 38
15 24
19 25
30 46
31 24
33 24
60 49


(3)
1.0605
1.0268
0.9302
0.9246
0.9296
0.9198
0.9460
0.9528
0.9076
1.0 131
1. 0284
0.9958(
1.0243
0.9567
0. 9696
0.9267
0.9591
0.0612
C.9491
0.8986
1.0468


# Flux


(5)
1.46
2.24
9.56
3.25
5.35
15.29
2.12
1.87
21.20
3.62
2.59
2.01
2.18
2.01
2.69
1.98
6.73
14.78
2.90
3.76
3.52
















Figure III-1. Sensitivity curve used for calibrating the 91 meter spectra. The data
points are taken from columns 2 and 3 of Table III-1. A parabola has
been fit to these points using the method of least squares. The sensi-
tivity S, in Jy/K, is related to the declination 6, in degrees, by

S = 0.99775 0.004408- 6 + 0.0000749- 62 + .02.

In order to calibrate each source, the spectral values of each channel
are multiplied by the appropriate value of S.













Si--- -- --i-- - --H-


N'

K
K


4 /

/










fli) 21' Sa* I li I F. gifl Sp'r









At the end of each of the two observing sessions, several days were

spent reducing the data at the NRAO headquarters in Charlottesville,

Virginia. The work was done on a CRT terminal using the NRAO T Power

and S Power programs. For each source, the ON and its corresponding

OFF were difference according to equation 111-9, and then all transits

were averaged. Any bad data, of course, were excluded. For sources

in which a spectral line was present, a polynomial curve was fit to

the baseline on either side of the spectral line. The lowest order

polynomial as was suitable was used, seldom going beyond third order.

This curve was then subtracted from the spectrum to leave a flat base-

line. The spectra were then recorded on a 9-track magnetic tape and

taken back to the University of Florida for further reduction.

At the University of Florida, corrections for the variation of

system sensitivity with declination and with hour angle were applied,

converting the spectral values from units of temperature to units of

flux. The two polarizations were averaged together and the spectra

were plotted on a Gould electrostatic plotter. Final RMS uncertainties

were on the order of 5-10 mJy per channel. These spectra are shown

in the next chapter. The computation of various parameters from these

spectra is also developed in the next chapter.


Observations on the 305 Meter Telescope


The 305 meter (1000 foot) telescope of Arecibo Observatory is

located in a mountainous region of Puerto Rico, approximately 15 km

south of the city of Arecibo. Its reflecting surface is a fixed

spherical aluminum dish, 305 meters in diameter and covering 18 acres.

A huge platform is suspended above the dish, supported by cables from









three large towers. The feeds are mounted beneath this platform and

can be steered to point anywhere within about 200 of the zenith.

Spherical aberration is corrected for by using line feeds. The 21 cm

feed has a range in declination between about -1 and +38.

The Arecibo observations described here were made in two observ-

ing sessions. A 17 day observing run was made in April and May of

1977. As these observations were quite successful, additional time

was requested. The second observing session, covering eight days, was

made in June and July of 1978.

The feed used for the 21 cm observations was a 40 foot line feed

which was illuminated by an annulus of approximately 210 meters outer

diameter and 90 meters inner diameter. The receivers were uncooled

parametric amplifiers which accepted the two circular polarizations

from the feed. For zenith angles of 100 or less, the feed was il-

luminated entirely by the reflecting surface of the telescope. Within

this range, the half power beamwidth was -3.3 arc minutes and system

temperatures were typically 70-80 K. At zenith angles greater than

100, the feed began picking up ground radiation, increasing the system

temperature. Other side effects were an increase in and a distortion

of the beamwidth, and a reduction in system sensitivity. This effect

was not too serious inside a 140 zenith angle. However, near the

zenith angle limit, the sensitivity dropped to -60% of its maximum

and the system temperatures rose to -150 K. For these reasons, most

of our observations were made within about 14 of the zenith, but a

few sources had to be observed at less favorable parts of the sky.

One of the biggest problems with this telescope is the uncertainty

in the position of the beam. The RMS pointing accuracy is on the order









of 30" of arc. Thus pointing errors of 1' of arc are not uncommon.

This uncertainty has the effect of limiting the determination of HI

masses to an accuracy of -20%.

The spectra were produced using 504 channels of a 1008 channel

autocorrelator. Each polarization was split into a spectrum of 252

channels. Total bandwidths of either 5 MHz or 10 MHz were used. The

channel spacing was approximately 4.2 km/sec with a resolution of ap-

proximately 5.1 km/sec at 5 MHz and twice these values at 10 MHz. With

a 5 MHz bandwidth, three level sampling of the data could be employed.

In this mode, the constant y in equation III-10 was -1.2. With a

10 MHz bandwidth, the autocorrelator was usable only as a one bit

sampler. In this case, y was -1.6. For a 5 MHz and a 10 MHz spectrum

of identical integration times and smoothed to the same velocity

resolution, the RMS uncertainty of the 5 MHz spectrum would be ap-

proximately 3/4 as much as the 10 MHz spectrum. Thus it was advan-

tageous to use a 5 MHz bandwidth.

All of the Arecibo observations were made in the total power mode.

An ON scan of five minutes duration was taken at the source position,

followed shortly afterwards with a five minute OFF scan covering the

same range in zenith angle and azimuth. The observations were monitored

on-line using a Harris Datacraft computer and a CRT terminal. The

Arecibo HI system is undoubtedly the most sensitive in the world. In

almost every case where a spectral line was present in the bandpass, it

was evident, though perhaps noisy, after the first set of ON and OFF

scans. In several cases, this allowed changing the observed velocity

to place the spectral line in the center of the bandpass. Most of the

observations were made using a 5 MHz bandwidth. A 10 MHz bandwidth was









employed at times to search for several Haro galaxies with unknown

velocities and several galaxies which did not show a spectral line at

the published optically determined velocities. If a signal was found,

the system was usually switched back to a 5 MHz bandwidth. Typically,

between three and ten sets of ON and OFF scans were taken for each

source to get a good signal to noise ratio and a low RMS uncertainty.

The 21 cm feed is tunable in frequency by moving it up or down in

its housing. For instance, to get maximum sensitivity at -1390 MHz, the

feed is moved 14 inches closer to the reflector than the normal focus

position for a frequency of 1415 MHz. Unfortunately, the feed cannot

be adjusted individually for each source as it requires several hours

for a single adjustment. For the two sets of observations reported

here, the feed was set for optimum sensitivity at a frequency of

-1415 MHz for about 60% of the observations andat -1390 MHz for about

40% of the observations.

The variation of telescope sensitivity with frequency for these two

settings of the feed has been determined by the Arecibo staff. Plots

of system sensitivity in K/Jy versus frequency were obtained from

Dr. Mike Davis, allowing the data to be calibrated and corrected for

this effect. Figure 111-2 shows the telescope sensitivity versus

frequency for the 1415 MHz setting. The peak sensitivity is -8.5 K/Jy.

Figure III-3 shows the same information for the 1390 MHz setting. The

peak sensitivity is -8.1 K/Jy for this setting. The sensitivity of

the system over the velocities observed ranged from -8.5 K/Jy to

-6 K/Jy.

Zenith angle corrections have also been determined by the Arecibo

staff. No correction is required for zenith angles of 100 or less.
























S6



N)
5








1395 MHz 1400 MHiz 1405 MHz 1410 MHz 1415 MHz

FREQUENCY

Figure III-2. Sensitivity versus frequency curve for the 305 meter telescope with
the feed set for optimum efficiency at a frequency of 1415 MHz, as
determined by the Arecibo Observatory staff.



















7 7
E-








5





1370 MHz 1375 MHz 1380 MHz 1385 MHz 1390 MHz 1395 MHz 1400 MHz 1405 MHz

FREQUENCY


Figure 111-3. Sensitivity versus frequency curve for the 305 meter telescope with the feed
set for optimum efficiency at a frequency of 1390 MHz, as determined by the
Arecibo Observatory staff.









For zenith angles greater than this, the relative gain is given by


Gain = exp [(-.00521) (ZA 10)2], III-13


where ZA is the zenith angle in degrees.

The noise tubes used for the 21 cm observations had to be cali-

brated, as their noise temperatures were not accurately known. This was

accomplished by making drift scans of continuum sources, as was done on

the 91 meter telescope. Sources were taken from Bridle et al. (1972).

Owing to pointing errors, a single drift scan was not sufficient for an

accurate calibration. Usually drifts were taken at the source declina-

tion and at declinations 1' of arc to the north and to the south. The

noise tubes were fired just before and after the source drifted through

the beam. The drift scans were recorded on a strip chart. With three

such drifts, the peak flux and the error in pointing could be obtained.

Using 1400 MHz fluxes from Bridle et al. (1972), the values of the

noise tubes were found in flux units. These values were then converted

to temperature units by multiplying by 8.5 K/Jy at the 1410 MHz

setting, and by 8.1 K/Jy at the 1390 MHz setting.

The observations taken in 1977 were partially reduced at Arecibo

Observatory using several programs written by Nathan Krumm. The

individual scans were averaged together and the spectra were punched

out on computer cards for further reduction at the University of

Florida. For the observations taken in 1978, the data were brought

back on magnetic tape and all the reductions were made at the University

of Florida. One program written by Martha Haynes and Steven Peterson

was used to convert the Arecibo data tape into an IBM readable tape.

Several other reduction programs, incorporating elements written by






35


Nathan Krumm and Martha Haynes, were developed by the author. The

spectra were calibrated for the variation of sensitivity due to zenith

angle, according to equation 111-13, and for the variation of sensi-

tivity with frequency, according to Figures 111-2 and III-3. The

spectra were plotted on a Gould electrostatic plotter. The final RMS

uncertainties were typically 1 -5 mJy per channel. The calculation

of various parameters from these spectra is given in the next chapter.















CHAPTER IV
THE DATA


Optical Parameters


Most of the optical parameters of the 99 compact galaxies observed

for this study are given in Table IV-1. The columns are numbered and

are explained below by column number. Following Table IV-1 is a list

of notes on the individual objects, giving alternate names and a brief

description.


Column 1: Source name.


Columns 2 and 3: Right Ascension (RA) and Declination (Dec) of the

source in 1950 coordinates. Positions have been measured by the

author on the Palomar Sky Survey (hereafter abbreviated PSS) plates

using an overlay program and a least squares fitting program. Posi-

tions are believed accurate to 2-3 arc seconds.


Column 4: V heliocentric velocity. The Doppler shifted velocities

with respect to the sun are taken from de Vaucouleurs et al. (1976)

unless otherwise noted (S implies Sargent, 1970b). De Vaucouleurs

et al. (1976) use weighted means of published velocities, most of which

are optically determined.


Column 5: The major axis (a") and the minor axis (b") in seconds of

arc. These are given in the system of de Vaucouleurs et al. (1976).








They are the approximate dimensions to a limiting surface brightness

level of the 25th magnitude per square arc second. The author has

measured the dimensions of 150 compact and noncompact active galaxies

on the blue plates-of the PSS using a low power microscope. For 138

of these objects whose dimensions are given in de Vaucouleurs et al.

(1976), the following regression formulae are found.

50 ......
For eSS 50 : e25 = 1.4 eSS 10 15 ,

IV-1

and for SS 2 50 : 25 = 1.01 pSS + 9 16 ,


where ePSS is the major or minor axis in arc seconds as measured on the

PSS, and 625 is the major or minor axis in arc seconds in the system of

de Vaucouleurs et al. (1976). Dimensions in column 5 identified with

a G are reduced from their PSS dimensions using equation IV-1. The

others are taken from de Vaucouleurs et al. (1976).


Column 6: Axial ratio, b/a. These are not strictly the ratio of the

optical dimensions in column 5 because these dimensions often include

irregularities such as double cores, filaments or jets. Since the

axial ratio is used to calculate the inclination of the system, such

irregularities are ignored in estimating the axial ratio. For multiple

or very peculiar systems, axial ratios are not given. These estimated

axial ratios cannot be considered extremely accurate due to the gen-

erally small dimensions and often irregular morphology of these sys- s.


Column 7: Inclination i, in degrees. The inclination is used to

estimate the total masses of these systems, assuming they are rot,- :ng

disk systems. It is not certain that blue compact galaxies are








rotating disk systems. O'Connell and Kraft (1972) and O'Connell (1979)

have shown that some of the blue nondwarf systems appear to rotate with

rotation curves similar to late type disk galaxies. Gottesman and

Weliachew (1972) found inconclusive evidence of rotation in one dwarf

compact galaxy. For compact galaxies, the observed axial ratios are

higher, on the average, than is seen in late type spiral galaxies.

This is an indication that, if these are disk systems, their intrinsic

axial ratios are greater than those of spiral galaxies. This problem

will be discussed more fully in Chapter V. For now, we will calculate

an inclination assuming that these are disk systems. For a disk of

intrinsic axial ratio q, and apparent axial ratio b/a, the inclination i

is given by

2 (b/a)2 q2
cos2 i = (b/a)2 q2 IV-2
1 q2

For normal spiral galaxies, q is believed to be between 0.2 and 0.25.

Very few spiral galaxies are found with b/a > 0.2. Only one galaxy in

our sample has b/a > 0.3. For compact galaxies then, we use q = 0.3

in equation IV-2 to compute the inclinations. This is similar to the

value of 0.33 used by Chamaraux (1977) for blue compacts. As in

column 6, inclinations are not given for multiple or very peculiar

systems.


Column 8: BT, blue magnitude, in the system of de Vaucouleurs et al.

(1976). Slightly less than half of our sources have BT magnitudes

listed in de Vaucouleurs et al. (1976). These are listed in column 8

with no further designation. Those marked with an H are taken from

Huchra (1977) and those marked with a P are from Huchra (1979). The








remainder, marked with a Z, are reduced from the photographic magni-

tudes given in Zwicky's Catalogue of Galaxies and of Clusters of

Galaxies (Zwicky et al., 1961, 1965; Zwicky and Herzog, 1963, 1966,

1968; Zwicky and Kowal, 1968) to B magnitudes. De Vaucouleurs and

Corwin (1979) have determined regression formulae to perform these

conversions and have personally calculated these magnitudes and com-

municated them to the author in advance of publication of the regression

techniques.


Column 9: BT, the total blue magnitude, in the system of de Vaucouleurs

et al. (1976). These are calculated from the BT magnitudes of column 8,

correcting them to the face-on, zero extinction, zero redshift values,

according to the precepts given in de Vaucouleurs et al. (1976).


Column 10: MBn, the absolute blue magnitude. These are calculated
T
using the BT magnitudes of column 9 and the distances given in either

Table IV-2 or Table IV-3.


Columns 11 and 12: (B-V)T and (U-B)T, color indexes, in the system of

de Vaucouleurs et al. (1976). These color indexes are corrected to

the face-on zero extinction, zero redshift values, according to the

precepts given in de Vaucouleurs et al. (1976). The symbol in column

12 gives the source of the color information. Colors from de Vaucouleurs

et al. (1976) are given with no symbol; H implies Huchra (1977); K

implies Khachikian and Weedman (1974); S implies Sargent (1970b); D

implies Du Puy (1970); and I implies Hiltner and Iriarte (1958).










Table IV-1. Optical Parameters


RA Dec Ve a" b" b/a i BT BT Mgo (B-V)T (U-B)T
RA Te T BTBT)


(2) (3)


M335
HAROU 1 4
I i I Z',:1 2
HAR( ) 16


1 I1 ZW33

VZL;;31
111I Z'42
1 I I ZW-t3.
HAR)20
VZN372
IIZ~ I1
11ZY 23
i lZw2S
I 1Z',33
11 Z452'
II ZW3b


11.6
VI IZW153
V11Zib01
H AR U
4385
1022

ZW4055
M 1 05
I Z w 11
.1 4 J 2
1 z I ? 1
H A -22
HA Fr:J23
11 /,4 4
HIAIA)2
M1l48
HARC3I
HAR1025
HA104


h m
0 3 4<
0 43 Ii
0 45 1;
0 45
0 57
1 13 1'
1 41 1.
1 41 4
1 54 5:
2 8 5(
2 11
3 25 5
4 10 4
4 35 5.
4 47
4 5)
5 a 1I
b 1 4 2
5 53
6( 0 2
5 45 4
7 22 1
7 23 3
7 31 3
3 0 2
8 4 2
8 32 2
a 55 4
9 1 4+
9 30 3
9 32 2
9 43 1
9 47
10 3 2
10 12 2
i0 29 2
10 32 3
10 42 1
13 4b
11 2 1


(4) (5) (6) (7) (8)


s o 1
5.1 19 53
6.5 -15 52
7.1 22 1
4.0 -12 59
3.6 31 33
9.5 32 49
J.9 16 43
7.9 16 51
3.. 27 37
0.5 13 4 1
3.8 .3 52
7.2 -17 35
).2 29 1
3.0 11 8
7.2 3 14
4.2 3 30
38. -2 44
4.6 0 52
4.Y 3 23
. 7 7 49
3.4 74 29
8.7 72 40
6.0 72; 13
9.1 3 21S1
7.3 25 14
1.0 39 ')
3.2 30 42
8.3 6 31
3.1 /1 J
0.0 5b: 27
2.0 33 37
3.1 45 159
7.H ;2:3 14
6.5 29 11
9.4 21 21
3.0 54 39
7.2 44 34
7.0 5b 13
0.1 26 19
5.4 29 24


7445
915554
59 541

6415
4477
4793
7964

8041
7743
3438a
1834
5342
4393
54 03
5i649
2B13 67
26607
72 20

5391!
5600

3470

804 1
7075
7147
3501
3562

7289
4965

1402
6166
b 1 6 (
1 4 4 6
7147
865

636


1 IG

1 7G
52G
52G
41
30
205
25G
5G66
48
4 .
90
22C
71
1 3.
47
16G
7 7G
24
76
59)
76
01l
4uG
4 0
37
47
2't+G
4 4 G
44G
o5
ol
49
35
900
6 7
95
19
19


'3 -33
0. 7 5
0 .90

0.751


0.97
0 0

0.50

0.31
.).77



1 .00
0. 33
1, 00
1 .0o
0.74
0 :,
0 50
(). 9.0
0.70
0 .* 1o
0. 73

0 6.3

0. i,
1 .00
0. 84
0.7
0 7 30
0. 76
0.60
0 /0
1.00
0. ;J1


(9) (10) (11) (12)


1'I 10
13.70
a15. 31z
13.90
1 7 /
15. 12
14 .89/

I 1. 3 1 /
I4.318Z
1 4. 31Z
14. 90


14 55Z
15.5
14.20Z

15.64P
17.60
14. 507
14.09Z
13. t69Z
12. 2

14.667
15.02Z
14 .73L
I s 027-
14 7 4 Z
16. ')
16.34H

14 .8 Z
15.2 0
14.00
15.94Z
1.3 0 0

13.20
15. 70
15.80H1


13.7'5
1', .* >

1 3 .415
14.2 4
14 .09
1 4 6

15.00
14 .51
14.0 5
14.44


13.33
14.94

13. t~h
14 22

1-3 *. .3
13.40
13.1 1
1 2. 3
14.57
14.33
14/.50
14.31
15 1
15.00

14.59
14 4
14.33
15.75
13.15

12.81
15 .52
15.51


3.23

0. 1 3

0.4
0.61
0.28


-3. 76
-3 .23
-3 .i '

-0 .66
-0.02
-3 3.)H


0. 3 -3. 0 S
0.15 -0. 3



0.26 -,.53
0.203 -0.63)


-21.35
-17.15
- i 9.05 5
- 2.1 .20
-1 9.72
-19.4 4
-20.o5

-20.20
-20 .(63
-19.31
-1 .45


-21 .32
-20.32
-19.30

-15.'55
-10.92
-20 5
1 9 7 7
-20.31
-21. 109
-20.02
--20 u-2
-20 .53
-20.44
-19.01
-1 /. 57
-14. 36

-19 54
-16.40
-16. 95
-110. O?
-1 3
0.0
-1. 7. 3 '
-1I9.51
-14.01


-0. 34.
-0 .0
-0.07<
- C 0 C)<
-0. '4
-0 43-1
-0 .* 9


0. 3 -0.2?
0.13 -0.7?-


4.20
03. 2 6
0. ?d




0. .11
0.31
0.31


-.3.35
-0.11
-0.223
-0.50
- 0). *7 0

-3.3)1
-0 .7 H


Source


(1)


0. 17
0.23

0.17
0.3'
0 :'









Table IV-1. Continued.


RA Dec


V a" b" b/a


i B BT B (B-V) (U-
T T MB0 (B-V)T (U-B)T
T


(2) (3) (4) (5) (6) (7) (8)


Source


(1)

I W26 f
m 1 6 59
HAR;]27
M 11 )
I I ZA"57
HARiGd

H Rn)29
4121 3
1.2R3J2
MR23J 1
.-,,r03j




II!Zw68
11 Z.67
r57
M23'5
4M241
L Z ,53
I I 1.H56
HAR C38
1270
Me 75
H A R'J 39
"iA 1 '142

HAi R J4
1 1.470
I wI 2 7 1



SZW 11 5
I [Z 1 1

1ZW123
VIl Z-631
4297


h 22m 4b.S
23 52.9
37 40.0
62 43.2
2 7 0.0
13 17.4
1 10 36.95
S20 50.0
1 23 50.5
30 10.7
241 32.0
2 42 11.7
12 ? J 37.
1 44 40.0
S44 42.1
2 't 16.9
2 55 37.1
2 56 10.0
2 3b 12.0
2 37 39.0
3 3 58.0
3 11 38.9
j Id 17.1
3 33 17.0
3 30 41.9
3 2:3 25.'
: 56 5.4
4 2 56. 5
4 33 5b./
4 41 14.1
14 4-3 55'.2
4 4)' 13.1
4 -32 47.3
4 53 23.4
5 1 50.0
5 31 19 .
5 34 .3.
5 3 4 B.0
S'33 50.5
. 3 1.2


6147
1318
2970
7202
6620
131 8
1502
7034
237

4 0 0S
95t,
7002
322

4239
5700
7550
7042
7445
7743
5043
0004
840
2697
S041

4 470


1147
122(
2530
54P5
48605
669
5520
663

4700


)97
46
51

93
72
JO1
1,4G
5.?
'3
87
47
:3 -
37
19G
lyo
1 6
79
71
3G G
30

70
104
7f,
Z l
79
5'G.
44
2201
261
,0
71

72
2 3
L03
U3
59
18
135
57


1.00
0. 5
0.64
O. y O


0. 75

0.90

0 60
0.60
0.9 )
o. t2
0.80
0.9 5
0.55
0.00
0. f
0 . 0

0.03
0. 50



0.30
0 73
0.32

0.3'
0.20
0 .* c


0.90


0 70
0.30

0.7;)


14.33Z
14.531
14.90


1 4 )J 3 2


14 .130





15.40
14. -30
14 0 0
1 .37
15.37
1 u. 1 1 l


15.20
134.0 Z

15.23Z
15.711
15. 79Z

14.75
14. 30
14.91Z
1 4 2 Z

15 1- 4Z
15.14Z

15. 73Z
13.35
13.45


13 .95
14. 13
14 5:
13.oO
13.21
14.49

14.24
14.147
13. /0
14.30
1 4. 86
1 .67

13.1.5
14.34
13,609
15.03
15.07
1 3 .17

14 10
1 4 7
13.1

14. 49
1i .74
1 ~ 0


13.34
14 4 7
1 .91
1 19
1'. 53
14.13
1 5 .tv
12.9'
12 98


0.54 -0.33H
0.40 -0.271
0.66 0.03


0.39 -0.'OD


0.11
0.4-,
3.27
0.21
0.4*
0.51


-0.43
-0.19
-0.330
-3.41
-3.25
-*.2 10


-17.20
-17.77
-20.37
-21.12
-1t.90
-16.90

-14.17
-20.01
-20.43
-10.10
-19.9
-14.32
-1 9 93

-14 .03

-20. 0o
-21 .33
-19.9 t
-19.93
-10.93


-20.75
-15.52
-19.29
-20.5)
-18.23
-10.19
-17.00

-17.24
-17. 44
-1 3 1
-20.4 7
-1 9 7
-1 5. 1 7
-23.23
-14.6 3
-20.D98
-21 0-


0.4' -0.29

0.77

0.33 -'.2?H
0.51 -0.12H


0.50 -0.35
0.42 -0.22K


0.33 -0.47D


0.11 '-0.85
0.3- -0. 1')



0.33 -0.14P

0.49 -0.53H

0.33 -0.46


(9) (10) (11) (12)













RA Dec


Table IV-1. Continued.


a" b" b/a i


BT BT MBo (B-V)T (U-B)T
T T BT T7


(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)


16 22 2.6
16 34 7. t
16 47 3.0
17 39 6.3
17 49 15.3
16 33 10.4
20 20 42.4
21 0 20.0
22 7 15.2
22 12 20.5
22 13 46.9
22 14 1.4
22 23 44.7
22 3' 0.0
23 3 30.5
23 17 35.0
23 23 11.7
21 27 40.3
23 35 9.


54 16 0
52 1I 56
480 47 34
47 45 20
56 41 10
b5 14 1 7
0 30 10
36 29 47
17 24 57
13 35 30
22 41 6
16 13 13
30 4) 17
23 o 46
16 20 0
25 56 25
23 10. 48
25 15 22
29 51 10


5432
26-2
7679
5793
5300
55/3
3975

70i80

3685
74+45
6710
7130



1308
*33510
i jaa


16 19G
15 18
30 30
12 135
27 37
17 43G
48 55J
45 5?G
14 175
61 61
43 2 .3
25 44
40 46
39 43
47 69
1a 2 1
97 102
1 255
25 35


1.00
0 a 40
0.93
1.00

0.837


1.00
0.63

0.90
0 630
0.753




O. ,3
0. 7'j
0.90

0.90


16.06Z 15.70 -17.20
15.31Z 15.03 -20.10


0.33 -0.30H


15.loZ 14 .82 1 .52

14.20 13.46 -20.2d 0.64


15.712 15.25 -19.05
13.70 13.23 -21.92


15.20




13.00
15.217
b1. 75Z


14.52
13.52
13.94
13.45
14.89
12.6o-
14 3
15.37


-20.44
-21.39
-21.02
-1a.93
-2).20
-20.75
-19.68
-16.24


0.90 0.45

0.4B -0.16H


0.39 -0.38H

0.25 -0.22

0.57 -0.12H


Source


IZW147
1Zo159
I Zw 166

I ZW 191
1 '4207
I I Zw 2
IVZ n 7
1 1L 153
IIZ a 72
1VZ 93.
:1333
Z:2220
11Z.'1850
11 2 1 3 3
IV! 1 4

1 VZ 149
1 vZ o 1 5 3
2I L A 3 -
Z W2.33





43


Notes to Table IV-1


M335 = A0003+19. Seyfert galaxy. Almost stellar; slight trace of
nebulosity; b/a rather uncertain.

Harol4 = MGC-3-3-3. Has large bright core not centered in nebulosity;
bright knot in ENE part of nebulosity (NGC244).

IIIZwl2 = M347 = IC1586. Nearly stellar core; hint of nebulosity.

Harol5 = M960 = MGC-2-3-19 = A0046-12. Large bright core with
nebulosity.

M352 = A0057+31. Seyfert. Small, nearly circular core; slight amount
of nebulosity; weak jet to W.

M1 = NGC449 = MGC5-4-9. Seyfert. Small, bright elliptical core with
a slight amount of nebulosity. Correctly identified in de Vaucouleurs,
et al. (1976), but incorrectly in Nilson (1973).

IIIZw33 = M360 = MGC3-5-13 = A0141+16. Bright elongated core; two
bright knots N of core imbedded in nebulosity; somewhat irregular,
nonuniform nebulosity. May be a distorted Scd (Huchra, 1977).

IIIZw35. Double compact system; in contact. Southern compact has
circular core; little nebulosity. Northern compact has bright
elliptical core; little nebulosity.

VZwl55 = M364 = A0154+27. Featureless; small circular core; very little
nebulosity.

IIIZw42 = M366 = A0208+13. Bright, nearly stellar, slightly elongated
core; clumpy irregular nebulosity not centered on core.

IIIZw43 = M589 = MGC1-6-56 = UGC1716 = A0211+03. Bright, nearly
stellar core; faint nebulosity.

Haro20 = MGC-3-9-45 = A0325-17. Small, uniform, elliptical core;
faint nebulosity.

VZw372 = MGC5-10-12 = A0410+29 = UGC2989(?). Bright, stellar nucleus;
faint, grainy and extensive nebulosity.

IIZwl8 = A0435+11. Round, bright, stellar core; some nebulosity; jet
to SE. May have faint outer spiral arms (Sargent, 1970b).

IIZw23 = M1087(?) = A0447+03 = UGC3179. Elliptical core with faint
jets; faint nebulosity.

IIZw28 = A0459+03. Round; slightly irregular; clumpy; little
nebulosity. Has a ring (Sargent, 1970b).









IIZw33 = M1094 = MGCO-14-10 = A0508-02. Elliptical, patchy, compact
core; perhaps composed of three clumps; irregular, patchy nebulosity.

IIZw35. Two stellar knots; very faint nebulosity.

IIZw40 = A0553+03. Approximately stellar core; very faint, grainy
nebulosity; two faint jets to SE; b/a very uncertain.

IIZw42 = MGC1-16-0 = A0600+07= UGC3393. Bright stellar core; little
nebulosity.

M6 = IC450 = MGC12-7-18 = UGC3547. Seyfert. Small, bright, elliptical
core; faint, fuzzy, irregular nebulosity.

VIIZwl53 = M7 = MGC12-7-38 = A0722+72 = UGC3838. Irregular, "tank"
shaped, compact core; small amount of nebulosity; b/a very uncertain.
U shaped core of knots (Huchra, 1977).

VIIZwl56 = M8 = IC2184 = MGC12-7-41 = UGC3852. Triangular shaped
clumpy core; triangular shaped nebulosity; b/a uncertain. Ring of
HII regions (Huchra, 1977).

Harol = NGC2415 = MGC6-17-21 = UGC3930. Slightly ellipsoidal,
irregular core; irregular nebulosity.

M385 = A0800+25. Bright, approximately stellar core; small amount of
nebulosity.

M622 = A0804+39 = UGC4229. Small, bright, almost circular core;
fairly dense, featureless nebulosity.

M390 = MGC5-20-28 = A0832+30. Bright, ellipsoidal, compact core; faint
nebulosity.

Zw0855 = MGC1-23-13 = A0855+06 = UGC4703. Unnamed object in Zwicky
(1971). Two tiny clumps, -87" apart; connected by a faint, thin
bridge; very strange object.

M105 = A0915+17. Small bright core; trace of nebulosity.

IZwl8 = M116 = A0930 A and B. Pair of interconnected compacts;
figure 8 shaped core with some nebulosity.

M402 = A0932+30. Elliptical core; very little nebulosity.

IZw21 = MGC8-18-30 = A0943+46 = UGC5225. Circular, nearly stellar core;
very faint nebulosity.

Haro22 = MGC5-23-40 = A0947+28. Bright, slightly elongated core;
small amount of nebulosity.

Haro23 = MGC5-24-11 = A1003+29. Small, ellipsoidal core, slight amount
of nebulosity.





45


IIZw44 = A1012+21. Small, semistellar core; main object is only -20"
in diameter; several possible nebulous objects within -45" are used
for the total dimensions.

Haro2 = M33= Arp233 = MGC9-17-70 = UGC5720 = A1029+54. Featureless,
ellipsoidal core and nebulosity.

M148 = A1032+44 = UGC5747. Bright irregular core; jets to SE and NW;
slight amount of nebulosity.

Haro3 = M35 = NGC3353 = MGC9-18-22 = UGC5860. Small bright core;
faint irregular nebulosity.

Haro25 = M727 = MGC4-26-9 = A1046+26. Stellar core; very slight trace
of nebulosity. DuPuy (1970) misidentified Haro25 with a red object.
Hiltner and Iriarte (1958) looked at the correct object.

Haro4 = M36 = MGC5-26-46 = A1102+29. Small, slightly elongated core;
small amount of nebulosity.

IZw26 = M40 = Arpl51 = VV144 = MGC9-19-73 = A1122+54. Seyfert. Thin
filament with two knots in it; very irregular object.

M169 = IC691 = MGC10-16-139 = UGC6447. Slightly elongated core; some
nebulosity; faint jet to S.

Haro27 = MGC5-28-10 = A1137+28 = UGC6637. Bright elongated core with
some nebulosity.

M198 = MGC8-22-73 = A1206+47. Bright, nearly stellar core; elliptical,
slightly irregular nebulosity.

IIZw57 = MGC3-31-49 = A1207+17. Bright elongated core; clumpy
nebulosity.

Haro28 = NGC4218 = MGC8-22-88 = UGC7283. Large, bright, slightly
irregular, elliptical core; small amount of nebulosity.

Haro8 = M49 = MGC1-31-50 = A1216+04 = UGC7354. Stellar core; slight
amount of nebulosity, mostly to SE.

M50 = A1220+02. Seyfert. Bright, nearly stellar core; slight trace
of nebulosity.

Haro29 = IZw36 = M209 = MGC8-23-35 = A1223+48. Strange appearance;
fan shaped nebulosity; bright compact core at western tip and compact
core in center; small bright object or jet to N; b/a very uncertain.

M215 = MGC8-23-52 = A1230+46. Small, bright, slightly elongated core;
small amount of nebulosity.

Haro32 = IZw41 = M220 and M221 = MGC9-21-33 and 34 = A1241+55 A and B
= UGC7905. Close compact pair; very irregular. Southern component has





46


bright core; slight amount of nebulosity. Northern component is very
irregular; bright elongated core; extensive curving nebulous region to
N and E.

Haro33 = MGC5-30-70 = A1242+28. Bright central knot; smaller knots to
ESE and WNW, interconnected with nebulosity.

Haro34 = IC3730. Bright, approximately stellar core; irregular
nebulosity; curving filament to N, like a single spiral arm.

Haro36 = MGC9-21-47 = UGC7950 = A1244+51. Bright central core; weak,
somewhat irregular nebulosity.

Haro35. Bright uniform core, shaped like a "combat" hat; virtually no
nebulosity.

Haro37 = M444 = MGC6-28-32 = A1246+34. Approximately stellar appear-
ance; faint haze; hint of faint jets.

IIIZw68 = MGC5-31-38 = A1255+27B = UGC8080. Bright, nearly circular
core; uniform elliptical nebulosity.

IIZw67 = NGC4853 = MGC5-31-48 = UGC8092. Slightly elongated core;
some nebulosity.

M57 = A1256+27B. Small, elongated, slightly irregular core; very
little nebulosity; faint jet to S.

M235 = MGC6-29-10 = A1257+33. Small elongated core, pointed at one
end; little nebulosity.

M241 = A1303+33. Bright elongated core; very little nebulosity.

IZw53 = A1311+35. Nearly stellar core; slightly elongated; virtually
no nebulosity.

IZw56 = IC883 = Arp193 = MGC6-29-0 = UGC8387. Bright elongated core;
some nebulosity; two jets to SE and to SW.

Haro38 = MGC5-32-41 = A1333+29 = UGC8578. Bright elongated core with
some nebulosity.

M270 = NGC5283 = MGC11-17-7 = UGC8672(?). Seyfert. Bright, nearly
stellar core; faint nebulosity.

M275 = MGC5-33-2 = A1346+31. Elongated, somewhat irregular core;
nebulosity with wispy features, perhaps hint of spiral structure.

Haro39. Bright, very elongated, cigar shaped core; very little
nebulosity.

Haro42 = M685 = MGC5-34-61 = A1428+27. Elongated core; faint
nebulosity; filaments to east.








Haro43 = MGC5-34-80. Very elongated bright core; very little nebulosity.

Haro44 = MGC5-35-8. Irregular, tear shaped core; small amount of
nebulosity; possibly a jet to N.

IIZw70 = M829 = MGC6-33-2 = VV324B = A1448+35 = UGC9560. Pair with
IIZw71, -250" apart; slightly elongated, nearly stellar core; nebulosity
mostly along major axis, like two streamers.

IIZw71 = MGC6-33-4 = VV324A = A1449+35 = UGC9562. Elongated with
central bulge; faint halo; perhaps an edge on galaxy.

IZw97 = A1452+42. Elongated core; very little nebulosity.

IZw98 = NGC5787 = MGC7-31-8 = UGC9599. Bright elongated core; exten-
sive elliptical nebulosity; axes of the core and of the nebulosity
differ by -45.

IZwlOl = IC1090 = MGC7-31-25. Small elongated core; slight amount of
nebulosity.

IZw115 = MGC8-28-38 = A1531+46 = UGC9893. Bright, crescent shaped
core embedded in elongated clumpy nebulosity.

IZwll7 = MGC7-32-30 and 31 = A1534+38 = UGC9922. Elongated core;
compact knot at northern tip; slight nebulosity; b/a rather uncertain.

IZw123 = M487 = A1535+55. Round, almost stellar core; slight amount
of nebulosity.

VIIZw631 = Seyfert's sextet = NGC6027 and companions = VV115 =
MGC4-38-5,6,7,8,9 and 10 = UGC10116. Compact group of six compact
galaxies; in a tight triangular cluster.

M297 = NGC6052 = Arp209 = VV86 = MGC4-38-22 = UGC10182. Irregular
object; two bright knots side by side; "hat" shaped appearance;
slight amount of nebulosity; b/a very uncertain.

IZw147 = A1622+54. Approximately stellar with fuzzy edges.

IZwl59 = A1634+52. Small, nearly stellar core; little nebulosity.

IZw166 = M499 = A1647+48A. Nearly stellar core; small amount of
nebulosity.

IZwl91 = A1739+47. Approximately stellar, fuzzy edges.

IZw199 = MGC9-29-39 and 40 = A1749+56 A and B. Small, interconnected
pair of compacts; -20" apart; small amount of nebulosity.

IZw207 = A1830+55. Seems very blue; arc shaped clumpy object;
"boomerang" shaped; very irregular.









IIZw82 = IC1317 = MGCO-52-4 = UGC11546. Elongated core; faint
nebulosity.

IVZw67 = MGC6-46-0(?) = UGC11668. Elongated core, perhaps double or
with a star at one tip; little nebulosity; possibly several faint jets.

IIZw168 = A2207+17. Nearly stellar, just slightly oblate core; slight
trace of nebulosity.

IIZw172 = NGC7236 and 7237 = Arpl69 = MGC2-56-23 and 24 = UGC11958.
Three small round compacts in a row; surrounded by nebulosity.

IVZw93 = A2213+22. Triangular shaped nucleus; perhaps made up of
three stellar or semistellar knots; surrounded by faint nebulosity.

M303 = NGC7244 = MGC3-56-21. Elongated core; clumpy nebulosity.

Zw2220 = A2220+30 A and B = UGC12011. Unnamed object in Zwicky (1971).
Interconnected pair of compacts; 16" apart. Western component has a
small elongated core; small amount of nebulosity. Eastern component
has a smaller elongated core; jet and small amount of nebulosity.

IIZw185 = IC5243 = MGC4-53-11 = UGC12153. Irregular; mostly dense
core; little nebulosity; curving tail, or perhaps single spiral arm;
b/a rather uncertain.

M314 = NGC7468 = MGC3-58-0 = UGC12329. Oblate, tear shaped core; some
nebulosity; faint thin jets extending from each side of major axis.

IVZwl42 = M322 = A2317+25. Bright elongated core; fuzzy edges.

IVZwl49 = NGC7673 = M325 = MGC4-55-14 = UGC12607. Large bright core,
pointed at southern end; small amount of nebulosity; short jet to N.

IVZwl53 = A2327+25. Double core; small amount of nebulosity.

Zw2335 = M328 = A2335+29. Bright, tear shaped core; small amount of
nebulosity.



Abbreviations used:

MGC: designation in the Morphological General Catalogue (Vorontsou-
Velyaminov et al., 1962).

UGC: designation in the Uppsala General Catalogue of Galaxies
(Nilson, 1973).

A: designation for sources without NGC or IC numbers in de Vaucouleurs
et al. (1976).

M: Markarian number.





49


Arp: designation in the Atlas of Peculiar Galaxies (Arp, 1966).

VV: designation in the Atlas and Catalogue of Interacting Galaxies
(Vorontsov-Velyaminov, 1958).

N: north

S: south

E: east

W: west









21 cm Global Parameters


Table IV-2 lists the global properties of the 72 systems which

were detected in HI. The columns are explained by column number and

line number.


Column 1, line 1: Source name.


Column 1, line 2: Designation for the telescope used. Thus N implies

the 91 meter NRAO telescope; A implies the 305 meter Arecibo Ob-

servatory telescope; AN implies both telescopes.


Column 2, line 1: V21, the heliocentric velocity, in km/sec, meas-

ured from the 21 cm spectrum. The velocity centroid is taken as the

velocity of the system. This is defined by

max
E V(n) -S(n)
n = min
21 max IV
E S(n)
n = min

where V(n) is the velocity of the center of the nth channel and S(n)

is the flux of the nth channel. The summations are carried out from

the minimum channel to the maximum channels containing the spectral

line.


Column 2, line 2: 6V21, the uncertainty in V21, in km/sec. This is

found by differentiating equation IV-3, which gives

max
(F V(n)) N V21
6V = n-mn .AS IV-4
21 max rms
E S(n)
n = min








where N is the number of channels containing the spectral line and

ASrms is the RMS uncertainty of the baseline, calculated from the

channels on each side of the spectral line. Values of 6V21 are rounded

up to the nearest integer. Equation IV-4 is strictly correct only if

the uncertainties are due entirely to random noise. But in practice,

errors in the pointing of the telescope and in fitting a baseline will

further limit the accuracy of V21.


Column 3, line 1: D, distance to the source in Mpc. The heliocentric

velocities, V21, are corrected to the velocity seen from the center of

the galaxy, VGC, by


VGC = V21 + 250 *sin L* cos B, IV-5


where L and B are the galactic longitude and latitude of the source.

The distance D is then found by dividing VGC by a Hubble constant of

75 km/sec/Mpc.


Column 3, line 2: A, the linear size of the major axis converted to

units of kpc. These are calculated using the distances from column 3,

line 1 and the major axis, a", given in Table IV-1.


Column 4: AV, the width of the 21 cm profile in km/sec. This velocity

width is measured at the points equal to 20% of the average flux after

boxcar smoothing over three channels, or at the 2a level after boxcar

smoothing over three channels if the average flux is too weak. The

RMS uncertainty, a, is calculated after smoothing over three channels.

The velocity widths listed are corrected for the boxcar smoothing.








Column 5, line 1: BCF, beam correction factor, applied to the HI

masses to correct for the finite width of the beam.

A radio telescope will underestimate the total flux from a radio

source, unless it is a point source centered in the beamwidth. For

extended sources, some way of correcting for this underestimation is

necessary. The 91 meter telescope has a 21 cm beamwidth of approxi-

mately 10:8 of arc at half power points. The shape of the beam is

approximately Gaussian, except near the first null. All of the sources

observed with the 91 meter telescope were much smaller than the beam-

width and so this deviation from Gaussian shape need not be taken into

account. The flux detected will be the convolution of the source flux

distribution and the beam pattern. If the HI surface density of the

source is distributed as an elliptical Gaussian with major and minor

axes half power dimensions of A and B arc minutes, then the ratio of

the total flux to the detected flux (from Fisher and Tully, 1975) will

be


BCF = (1 + (A/10.8)2)/2 (1 + (B/10.8)2) 1/2 IV-6


Unfortunately, the values of A and B are not known. For sim-

plicity, we assume that they are some multiple of the optical dimen-

sions, a" and b". Converting to minutes of arc, we have A = F -a"/60

and B = F b"/60, where F is this unknown multiple. For spiral galaxies,

the HI distribution is typically found to be somewhat greater than

the optical distribution. Thus we expect F to be greater than unity.

The 305 meter telescope has a half power beamwidth of approxi-

mately 3.3 of arc at 21 cm. This is not small compared to the dimen-

sions of many of our sources. Additionally, the departure of the beam









pattern from a Gaussian is significant enough that an equation of the

form of equation IV-6 is not sufficiently accurate. The sidelobes of

the beam may also contribute to the detected flux and need to be con-

sidered as well. A numerical model of the Arecibo beam, including its

first two sidelobes, was constructed. The source size and distribution

is considered as in the previous case. The beam pattern and the source

shape are then convolved numerically to determine a beam correction

factor. Due to the pointing errors of the 305 meter telescope, this

convolution also includes the effects of a 30" of arc pointing error.

Again the factor F is unknown.

However, several sources were observed successfully with both

telescopes. In the analysis of the HI masses of these sources, a value

of F was found that led to the same corrected HI masses on both tele-

scopes. The values of F found for 13 sources ranged from 1.0 up to 5.2

with an average of 2.4393. Thus for the other sources, a value for

F of 2.4 is assumed, with a few exceptions, all of those being multiple

galaxies.


Column 5, line 2: F, the ratio of optical to HI dimension assumed

for the calculation of the beam correction factor of column 5, line 1.


Column 6, line 1: MHI, the HI mass expressed in solar mass units and

corrected for the beamwidth effect. The uncorrected HI mass is found

by converting equation III-6 to a summation of the form


1 5 2 max
MHI= 2.356 x 10 D E S(v) Av, IV-7
n = min


where the summation is carried out from the minimum to the maximum








channel numbers containing the spectral line, and Av is the channel

spacing in km/sec. The corrected HI mass is then found by multiplying

by BCF of column 5.


Column 6, line 2: AMHI, the uncertainty in the HI mass. This is found

by differentiating the equation for corrected HI mass. One gets


AMHI = 2.356 x 105 D2 VN Av ASrms BCF. IV-8



Column 7: LBo, total blue luminosity in solar units. These are
T
calculated from the absolute magnitudes, BT given in Table IV-7 and

assuming the absolute B magnitude of the sun to be +5.41 (Allen, 1964).


Column 8: Mi, indicative total mass, in solar units. We use the

equation used by Shostak (1978) for late type galaxies:


M. = 2.45 x 104 A (AV/sin i)2 IV-9


Total masses will be discussed in more detail in Chapter V.


Column 9: MHI/L, column 6 divided by column 7.


Column 10: M./L, column 8 divided by column 7.


Column 11: MHI/Mi, column 6 divided by column 8.


Table IV-3 lists a limited amount of data for 27 systems which

were not detected in HI. The columns are explained by number.


Column 1: Source name.










Table IV-2. Global Parameters of Detected Sources.


Source V2 D AV BCF MHI L M MHI/L M /L MH/M
Telescope 21 HI BT HIi
6V21 A F AMHI
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

lHAR- 14 940 13.2 04 1.0H03 1.805C 0!9 1.057LZ 09 4.184!L 09 0.171 3. '5 0.043
N 3 5.1 2.400 1.6 7 07
I11ZW12 5830 U0.0 200 1.0992 3.Cr00 09 1.070, 10 9 .54F 09 V .280 0. .892 0.314
A 11 6.6 2. .00 2.03E 0"I
HARalS 6407 86.0 220 1.0239 5..l ;I 0 4.3)5F 10 J.t'- 4E 10 0.126 0.331 0.152
1 10 21.7 2.400 1.79E 09
'1352 4442 62.0 242 1.3211 3.142 '- 09 1 .12'9 10 3. 1 87 10 0.276 2.023 0.)93
A 12 15.6 2. 400 2. 1L 0"
M1 4039 67.0 259 1 .2b4 3.339C 09 B.743' 09 4.551E 10 0.'38 5-.202 3.073
A 12 13.3 2.4/)0 2.347 0)4
1:1 ZW3 83057 139.0 245 1.1 ,40 C.2)'F' 0' 2.606E 10 6.473F 10 0.315 2.434 0.132
A 3 15. 2.400 3.31F 0 oL
!lIZW35 0222 111.0 109 1.0941 3.309F 09'
A 6 10.8 2.40J 2.j4E 06
1!1Z'42 7 49' 107.0 89 1.4170 1.IGOti' 099 2.614E 10 1.424' 10 0.051 0.51'5 0.1 J
A 6 29.0 2.4'00 2. :i r 0
111 -43 3444 47.0 186 1.30,7 1.014 l 09 7.727 09 3.030E 10 0.131 3.9:3 0.333
AN 16 10.9 1.000 3.00 0'I
HAR020 1553 24.0 141 1.01?4 4..202- 03 1.402E 09 3.7209 09 0.300 2.650 0.113
N 1b 5.6 2. 400 7. 1 5t 07
VZW372 5454 73.0 101 1.3749 1.140E 0 9. 655 09- 0.1 1
4 4 31.8 2.400 2.35; O'H
1IZ,.18 44*i5 59.0 280 1.1107 1.511F 0,) 2.701_ 10 0.0O
A 5 6.3 2.400 '). 2ii 07
IIZA23 8330 110.0 270 1.2303 1.71 t:. 1 4.934E' 10 1.7 1E 11 0.349 3.,10 0.096
A 10 37* ,.400 1.32": r,,
!L ?33 2820 36.0 153 1.0235 1.7'0C F : 7.f6926 09 8.391E 0) 3.222 1.091 0. '03
'1 2 3.2 2.400 91- 0
IIZw40 795 9.0 173 1.0722 J.45'[. 09 2.41y 0 g 6.011 09 1.430 24. 35) ?.)0
AN 2 3.3 2.4,1 2.04e 07
1IZ.42 5263 6).*0 1.1440 5.A b:? 0' 4.' '20 09 119
A 6 4f.0 2.4 '0 9. 92 0
VII 1 153 3350 43.0 232 1.0233 2.!10!1- 0) 1.177E 10 2.115E 10 0.231 1.797 0.132
N 2 12.3 2.403 j .GC 01
V11ZW156 3595 50.0 243 1.J676 5 .60; 0' 1.974E 10 5.734E 10 0.233 3.11 0.06) j
N 3 16.4 2.400 3.12 0.-
HARG1 3797 53.0 250 1 .0367 96.039- 9 4 .0j0- 10 1.O R4F 11 0. 150 2..:) 0.0'i,
AN 1 14.0 ,.03 2..1' 3










Table IV-2. Continued.


Mi MHI/L M /L MHI/Mi


Source
Telescope

(1)


A
,490
A
7 9055
A


M4 02
A
HAHU022
-\N
HAG,23
A
1 7 A44
AN


'I
HAR3
N

A
HIA R204

11 6)
N
HARG027
A
I 1 Z 1i'j 7
A


HAO 32
N
H ANOS
A
H -3]29)

HARO32
N


(11)
0 036

0. 97


V21

V21
(2)

0300
100
7640
22
3733
915
75)
2
7416

14'43
2
1372
2
6201
10
1467
4
943
2
7630
5
640
2
1233
2
1936


12
6(14
3
721
2
1515
3
281
2
493-3
3


D

A

(3)

109.0
24 .3
101 .0
1 .1
10 .





13.1
2.3

98.0

1.3
2n .0
6.5

10; .0
9 .3
5 .0
0. 7
17.0

3 .13l
3.8
24 .0
5.9)
JO )
3 ).7

3.7
19.0n
3 .b
4 .'3
1.?
57 .0
29 .*


BCF

F

(5)

1.29-49
2.4 00
1 2053
2.4 00
2.400
1 0 1
2.. 43
1.1 3 4-
2.400
1. 3133
1. 36
1 .23'.9
2.400
1.325 3

1.00 '1
2 .4C0
1 0 '39
. 400
1.113
?. 400
1.10.54
1 1 0 P,
2. 4 J0

2.4 0
1 .30O1

2. '400
2 .3 7 .'&
2? ? ,0
1 04'
2.400
2 .' 1 0
1.0337
2. 410 ,,)
1.0 707
-' 4 0 0


MHI

AMHI
(6)

1.027' 09
4 .49 2 03
6.571r O0
1.')IE 011
7. 815 Os
'r..t.r 07
E.313i 07
.3. S F
2 01 ',1 0 ')

2.5 E ,} 0
2. '31: 07
o .9554F o 0
'. 30' 0,O
1 .21 :, 10
8. 3.':1 0-
4.71.37 In
3.(67c 07
5. JO'U 01
1.2;" 07
1.7";3: ).
S 7 3,1 )E )
1 *, ,.37 ( 7




9 1. E- 0
2 ., 01-. 0 .
3. 4 0 ')
2.O ".OS 'OI


o.' 7E O
5.00 1.- 0 7
.. 32:' 0
R5.?21 0I


LB.o
BT

(7)
2.583B 10

2. 192 10

1.8453 3 09

0. 125E 07



5.2,351 Ob

U. 79 6 0'

4.924- 09O

3.21 lEc 09

1 .') 7:" 0-)

9..'-13 O'1 )



1. Y191' 01)

1. 366- 09

4.10 7C1 10

b.373,- 0,O

H. 43J'E 0O

G.7 74' 07

2. 1657 10


(8)
2.892F 10

&.710F 10




2.'568E 10

5.193E 00

1.1 7-E 0o

0.0

1.483E 10

5.0 t 1 0 -)



4.471 00

4.462E 0 )

6. 0250 0O

1 31i 3 9 -.' I 1

3.750C 09

1.0 ',7' 09

1.002E 0q


(9) (10)
0.040 1.120

0.300 3.079

0. 134

1 053

0.0 0.3

0.4 3 9.5335

0.075 1.340

2.463 0. )

0. 14I? 4.620

0.270 2.534

0. 620

0.'30 7.03

0.440 4.027

0.124 1.229

0. 95 3.260

0.253 4. 49 -

0. 1 2.347

0.73) 14. 712

.0 407


3.114

0.050

0 .056

3.0

O.032

0. 10i



0. ) 43










0.0'30
O) .01 1






1.050










Table IV-2. Continued.


Mi MHI/L M/L MHI/M


Source
Telescope

(1)

HAR033


A
H AR036
N

A



A
M53

1241

1 Z 53
A
HAR038
A
S27 5
A
HAI PC39
AN
H AR342
A
HA 0,Z43
A
H A R<44
A
I1 Zw70
A
11 ZW7 1
A
I Z 10 1
N
I Z115
IZiI17
IZN117
N


V21.

6V21
(2)

93,9
2
70 '1
2
491
2
7452
4
4280
2


7959
3
5143
100
8,4

7937
4
25' 7
3
4465
-3
1012
2
3725

1207

12501

4933

652
2
,596
4


D

A

(3)

12.5
2.
93 .
10.4
7.9
3.3
99.0
9.1
58.0
4.5
102.0
13.8
105.0
14.2
69.0
2.3
12.0
4.4
1 06.0
40 .6
35.0
9.5
G1 .0
13.0
27.0

51 .0
6.4



6.2
6 0
7.
11.0
4 '.
77.0
22 .,


BCF

F

(5)

1. 0162?
12.134
1. 137
2. 400
1.03 H44
2 i) )

2. 40')
1 '001
2. 400
1.1036
2. 'tOO
1 .16 2 ?

2. 0I '0
2. ) 02
2.400
1 .4I ;'

2.400
2.3'96?





2. 400
1.1217
2. 400

2. '400
1 3 117
2. 4 )





1.7531
2. 400
1.4031

1 .006
2. '0 0
1.0531
2. 400
1.02 70
2 400


MHI
AMHI
(6)

1. 9 ,Ji 0 1
1.03= 07
7.039L 09
1.93:C 0

1.O1E 07
2. 'JJF 09
1. ')01L 0-
i ri r0 '
7. '4E 07
2.21I. 0'i

L3.t, 3: 0o'

2.Q-)E 0O

2.4 0 0'O
3. 31LC 07

1 5"Ic o0
4.5.EC 0j
1 500" 00
9.OL 07
3. 312' 09
!. 03 0(.>'
'.923. f O,-;
1.70'" 07
1.213'C 0
'. o*,'E 0
3.2ho0 O3
7.51F 05
9.21 3E Oi
I .3:E 0'7

4.02E O-0
1.43 7 01
6. 7' 00
'1 1 O'Li-
1 3 1 0*J


LB0
T

(7)

4.003E OB

1.435;E 10

1.237: ON0



4.151- 09-

1.4 J 3 10

7. 185 0')



2.358E 00

2. 54l'i 10

2.'0U50o 00

. '20E3 09

'9.370E 06O



1 .1571 09

2. 10'J 0')

5.071C 0'3

2.715 U00

1. 062 10


(9) (10)

0.490 4.995

0.491 6.9-13

1.0 39 I').225



0.24'5 2.331

0.157 3.195

0.272 1.869



0.381 11.079

0.33'3 1. 86

0. 561 3. 16

0.479 2.4

0.600 1.651


(8)

2.000E 09

1.02E 1i

2.037E 09

4.0 3F 0

9.67-jE 0i

4.515E 10

1. 3'3E 1 0



2. 01E 09

4.301E 10

1.116E 10

1.7220F 10

1.6300 0'-

5.71T7e 09

3.103' 09

I.211: 09

1. 720'i 10


2.710

3. 204

3. 04


0 .542

5.U62E 10 0.434


(11)

0.093

0.070


0 .529

0.103

0. 34'.





0.032

0. 17

0.143

0.192
0 1')2
0 .3. 3

0.212

3.106

0.12 -

0.227


3.109 3.140


0.28')

0.421

0. 92










Table IV-2. Continued.


Source
Telescope

(1)

IZW123
N
VI IZ r631
A
M:'.? 7
AN
IZW166
0
T 7./#.07
N
IIZI 168
A
IVz ?93
AN
A

ZW2220

11ZW185
AN

AN
IVZW14A 2
A
IV 149

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AN.
ZwA335
AN


V21

6V21

(2)

677
2
4542
.3
4 7331
10
773J
53)
5631
3
8046
11
3855
6
7543
3
671 '
53

207~3
2
2063

4
3402
2
573+
5
1363
3


Mi MHI/L Mi/L MHI/Mi


D

A

(3)


(8) (9) (10)

1.639E 09 0.43b 12.735
0.075

1.835E 11 0.29'9 4.777
1 .50'3


(11)
0.034


3.063


AV BCF

F

(4) (5)

118 1.00O40
2. 40)
233 1 .? t39
1. 500
490 1.3040
2.567
1. 1 372 -
4. 000
109 1.0 14i
2.400
145 1.0972
2. 400
186 1. 10

287 1.23:25
2. 400
189 1 .0255
2. 400
180 1.074 1
4 J 1 ,
223 1.0213
.01
1.1077
2.400
220 2.7023
2 40')
294 1.3012
1.000
134 1.05-0
1* 't


MHI

AMHI
(6)

s 60" "4
9 .56
2.r699y
1 .431
1.179
5. 1,j5
2.404F

2.194F
3. 6 53E
3. 7

I 7 -
5. 1Ob 4
3.:34T

9.50-
1.192"
6.17C
2.602C
1. 04
2 .55 "'
(. 40 i

1 .63-:
6. '146!
4. 712
I .57 )9
2.87F


11.5
1.0
62.0
40.3


1 06 5 0
13.3
106.0
15. .3


113.0
.1 .
54.0
16.2
103.0
22.0
9 .0
21 .4
91.0
2 0 4
0 .4
30.0
10.3
109.0
11.1




3.5


0.076



0 .130

0. 141



0.072



0021


1.399F. 10 1.531F 10 0.182 1.094 0..166


I 2 7E/
1.2072

3.003-

3. ')4,5I

1 .5 7C


2. 162 10

5.243F 10

3. 721E 10

5.' %5 0o)

1.911E 10

2. 91 JC 10

1. 0')91 10

4. 561 E 011


u.6(33 10 0.231 3.046
0. 109

3.5b0O 10 0.320 2.300

1 .844E 10 0.476 3. 3 7
0. 134

1.348F 1 1 0.332 4.0L23

0 .627

7.471E 09 0.346 16.380








Notes to Table IV-2

VZw372: The spectra contains a strong source at V : 5800 km/sec in
the sidelobe of the 305 meter telescope.

Zw0855: The spectra shows two emission features. It is uncertain
whether both features are from this double object.

IIZw44: There is a difference of -4 times in the uncorrected HI masses
determined with the 91 meter and the 305 meter telescope. This could
be due to a giant HI halo. This object needs more careful study.

Haro22 and Haro39: No optical velocities were known. Their HI
emission lines were found by searching over a large range of veloci-
ties with the 91 meter telescope.

Haro35, Haro43 and Haro44: No optical velocities were known. Their
HI emission lines were found by searching over a large range of
velocities with the 305 meter telescope.

IZwl66: Confused in HI with two or three nearby galaxies. The HI
mass is for all these sources. It is not known which feature is due
to IZw166. This mass is not used in the analysis in the next chapter.

VIIZw631: Unfortunately, a 10 MHz bandwidth could not be used at the
time of observation, due to autocorrelator problems. There could be
emission outside of our 5 MHz bandwidth from this group of six
galaxies, which would have been missed. This HI mass is not used in
the analysis in the next chapter.








Column 2: D, distance to the source in Mpc. These are calculated in

the same manner as in Table IV-2, except that the heliocentric veloci-

ties are taken from the optical velocities of Table IV-1.


Column 3: A, major axis in kpc, calculated the same way as in

Table IV-2.


Column 4: MHImax upper limit to the HI mass. This is found by
max
taking three times the uncertainty defined by equation IV-8, and

assuming the velocity width is no greater than 400 km/sec. An N or

an A indicates which telescope was used, as in Table IV-2.


Column 5: L o, total blue luminosity, in solar units, calculated as
T
in Table IV-2.


Spectra of the detected systems are presented in Figure IV-1. The

source name is given in the upper left corner. The telescope used,

either the 305 meter or the 91 meter telescope, is indicated in the

upper right corner. The X axis gives the velocity in km/sec. For

spectra taken with the 91 meter telescope, the velocities are helio-

centric. For those taken with the 305 meter telescope, the velocities

are with respect to the Local Standard of Rest. The Y axis gives the

intensity of the channel values in Janskys. The two vertical bars,

one to each side of the spectral line, indicates the velocity range

which was integrated to determine the HI mass. All of the spectra

have been boxcar smoothed over three channels.













Table IV-3. Nondetected Sources.


Source D A MHI LBo
Hmax T
(1) (2) (3) (4) (5)

M335 103.0 5.3 1.2E 0-, 9AN 5.047E 10
VZWIl5 111.0 13 3 2.7E 09A 1.7 59 10
IIZ.v2y 113.0 '.9 2.2E 09A 1.61 E 10
11L~35 96.0 7.4 1.2E 0OA
N, 76.0 23.0 2.-: 3 09N 2.402 10
:4522 94. 0 13.2 1 .7E OJN 2.33"- 11)
"4105 49.3 .7 5.1E ,O)N 1.5b52 09
7IZ,,21 61.0 19.q 2.5E iN ').b94 09
114. 96.0 44.2 3.8E 99N
.Z 3 >' .3 o. 2.4E 09N
'1l8 97.0 20.7 2.3[ 09N 2.050E 10
150 92.0 o.2 1.3E 09A
.121 5 79.3 0.9 ?.2E 09 1 1.479: 10
IIlZWb8 76.0 20.1 7.5E 03A 1.5~7E 10
I IZWL 7 101.0 34. 1. O 034, A 4.'398A- 10
%12.3 10).0 14. '5 1].E6= A I 1C,'5: 1 ,
I w56 43.3 46.9 3.OE 094 2..900r 1 0
73 0 .38.0 14.9 3.5E 0() 7.577F' 0')
17 7 36.0 9.1 2.7E 08N 3.07 3 00f)
1ZA'-)? 75.0 26.2 1 091H 2.242E 10
lZw147 75.0 .9 9.7E 0 N
17 15 38.0 3.3 3. 5 03 N 1.1031r 09
IZW 191 10.1) '5,) I .oI 0C.N
ILZ. 9) 74.0 13.3 1.I1 n. N 9. '42. 0')
I Z." ,32 56.3 14.9 6.SE 0 N 1., ,3 10
IVZ .VG7 39.0 9 3 .C s A9
11 ZW172 107.0 31.6 1 .7t 0')A 2'-:F 10





















The HI spectra. The source name is given in the upper left corner of each spectrum. The
telescope used is given in the upper right corner. Velocities run along the horizontal
axis, in km/sec. For spectra taken with the 91 meter telescope, the velocities are with
respect to the sun. For those taken with the 305 meter telescope, the velocities are with
respect to the local standard of rest. The vertical axis is the flux strength in Janskys.
The vertical lines to each side of the spectral feature indicates the velocity range over
which the HI mass is calculated.


Figure IV-1.

















L-F: I ilLO F i4A F.8 0 1
-LL I JL I Li







']~ 7'
~FI ~--.1 J-F F Fil

H A F 1FIETi


200 1 ll 10' -1 ".111
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- . -- I I I- - l-- ....F]..[. .I- -I .--- 111Th ii---i--i---
F- II, -I- F /
LTFIE. T M E
f1 IZ.1 I I




I.i :I ; r j -lA I I I -I L i 0 II .ii L I I 0 nI ,I 1 11 I .
I _ ..-T i ._- 11 I --1 -.
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i, llIi 'II.

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SL _. I _. .L__ -. _...._L ... l _l l_ 1 I I ..-. _. [ L_ I
,0 ,-, i -I IJ j 8 1 I.I ll iK .1 I iO 'l ,-l'i!1i 4 I I 4 i 'tI L. f l- I, l l i L- i !, -1,)
Table IV-1. (Continued)









-I ---.- ----T
[ l r i ME ir n








) :lijpil i... 4~'00


I ZLI'I iV'r


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2L00 isIui 32i0ii i:ii0


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i -
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21lOI 2 11iLI 3200 00i 1 IiiF1l
Table IV-1. Continued.


i L L __ I _I _
7,",n ,11I11 77i,


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1;,,lU F, l II U-,Z !I"


....__L.L L_ LLL_I_I.L_J.._ I_. I


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76


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--- ~ ~ ~ ~ ~ ~ ~ ~ Ir 1---r- l-- l-1-1---


r~ 1-II iIU ,1T 1_- I Yr F LL

hiL~liJ; 'ii

Ii Li-..l LI L..1...I __L h _! 1~. 1
TableL JV-l._1 (Cotnued


I










- - I-r-- I T -i -I F
I I Z idi5 10 ; 1EThLh









t o uCi|i-ii f6 0n 0 rlO.io 7cuii



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L I I L -_1 il
1:I ll Il il ; 11[111


Table IV-l .
Table IV-l. (Ci


1 ntinue
continued


I'L~iJI


- IUI


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T -F- T- T--- 1'-- -7 -i,.,-F 1 -1 1 l-* 1^7 |P, 3"i
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.I.--I, _b 9 1. I- t I F Hl- -' ,FERl F -, -;- -. -..


j-oil 7 0 10 400 0 F0
k E r;
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h 0l.1 b'll l, i 7101.1 I
Table IV-1. (Continued).







T-1-~-I-- -I- rr--T-I--T







SFJLili o Tii i O '-F I I I -U L I r siu

II B F MEHTE H

1 (II
\J .

I I E

F L_J ..1 L__LL I__Ij_L_L__. .
-_ Hill l 'L- I ,Ii l PTE _
HO ^


.I C'LI_ l
Table IV-1.


II I i LI
2 I11] I I l I0
(Continued)


I- n -
" /I I'i Ii--


T



T iJ

Ill0 iI I l J u 1 :il l i IU



S*I1
i__ J_ L__I I__- _zjiL .i _LJ




I i - --1 l -i ... I .. -i
1 r' i Lit,.l _,ru ~ ,Il- r!i


I -7
1/Wilt 1


- I ML I F


_.J._-_ !i .L..-_J__ ..--
i\.i :ji' ,l 11 I i n ,LI ,i



fAI j .1 A, I


1 1 F TI I Wl ', 1 111
I - I 111r_ ,- - I li T L -


7Lij 91 m 1 l 1100 1:i0 iH









I: _. V I Z -







i I I 0
9 ~I. j I 9


!._'t i kI


I. I i l l r,.-. I'i


i I


LLLJ


J 1 t .I .L I,
Ta_.L_ LV-. (C_1

Table IV-1. (C


-I----- ... M
:05 METER


I 11710 4 l'll'l 5 1
T T-[....T---
1 II _1LILF










-F 1 .
;)I I 11110 ZL 11OJ



S1 I





:I h 500 H i:,:20 I
continued)


S.. I -1
I' c3 7A J 91

L l




I __F F_ .-- --




l l I tL l {I A I l _L



s ,t -


TT -
METER







_J__. I__


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I_! II i


I1 r I IJ'I qi I I I 11


M1 O 3


T ---1- TF
0 8-


n-r~
i T-. METL i
C M1 ETE VI -


1711U 1I 711i Fl L ? --l iF .uI. U
SI[ II-;li II ^*I^ 1








S__i _i .._I- .. -LL--_l-_ L ..- J
i, I I1 7t~lll: :::;I.HII I b l~ i E l I, _-I-


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i I'l,I i _111


F ul fltl t








b i l l i l ti l:l


,'J


72u0 7/, 11 I I 10 LI I &L0Q1







F-r----r T Fr-T 1F- -nI--r-- 1 r- T
STi JHETEh L MEr Ii





L Li LI11h -IJ 1 i-L-A -\.4 f1--- '-- I.
li lIil Jl L L_ L


LII Ci' l I Eclll iiiO 71 j''I ,*lSIII
I I F 1i
I i j1't II MLtFii

li tI~I


L__ 11_.. ..LLj L _
IT0 b;h I :i 'U Itii1l w "
Table IV-1. (Continued)


1|'1.1i


I IF q I T I I I







11 Sl --_ -- .l.. .l T ---J .....1-_ --r- f-l. 1 I_ I.-U- I- L- LF_ --. I
0 1






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Shlull Fu 0 .(Hi 70HU1 Ibul oilll itiuUl liil O 2011I C1ison


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Table IV- .


Lt IIII I 11-1
- - ]
_ _.J .-_^ ^-,


I _.l_ I.._. I


- I i II
_J 61H 1c'H


'i.U l l i l
(Continued)


I LI


-I I 15~C! Ii '








~I I I I
I l I i ,11


r
F















CHAPTER V
ANALYSIS OF THE DATA


The properties of blue compact galaxies seem to be more similar to

those of late type galaxies of the Hubble sequence than to any other

type. O'Connell (1979) found that the rotation curves of six luminous

blue compact systems were quite similar to those of late type galaxies.

Total masses, however, were found to be somewhat low for late type

galaxies. Studies by Fairall (1978) and O'Connell (1979) indicate that

many of the more luminous compact galaxies show some faint underlying

structure, indicative of late type systems. Neutral hydrogen studies

by Chamaraux (1977) indicate that the total masses and the HI masses of

blue compact galaxies extend into the same range as those of late type

galaxies. Finally, Huchra (1977) concludes that Markarian galaxies are

mostly late type systems.

We would like to compare the properties of the blue compact

galaxies in our sample with those of late type systems to see how

closely related the two types are. The best sample currently available

of the optical and HI properties of late type galaxies has been pub-

lished by Shostak (1978). Shostak's study utilizes the same system of

dimensions and magnitudes as our study of blue compacts. Thus we are

able to compare the properties of the two samples without any conversion

between the two. Of Shostak's (1978) survey of 169 late type systems,

we omit any which are peculiar, multiple, or confused in their HI.

This leaves 139 late type systems for comparison against the 72 blue









compact systems detected in HI. After a discussion of the selection

effects involved in our sample of blue compact galaxies, we will

compare their basic global properties to those of these late type

galaxies.


Selection Effects and Completeness of the Sample


Our list of 99 compact systems was drawn from the lists of Zwicky,

Markarian and Haro. Only the Markarian catalog is a reasonably

complete list.

Our selection of compact objects from the Zwicky (1971) list was

made from among the systems with published Doppler velocities. Many

of these were determined by Sargent (1970b), whose study was heavily

weighted toward the bluest Zwicky compacts, with the expectation that

they would be the most interesting to study. Since all the Zwicky

compacts with known velocities could not be observed in this study,

blue systems were selected preferentially over red objects, for it was

believed they would contain more neutral hydrogen. Thus, the sample

of Zwicky compact galaxies on our list is heavily weighted towards the

blue and very blue systems. Any statistics determined for Zwicky com-

pacts in general are not applicable to this study. However, the blue

and very blue Zwicky compacts can be considered together with Markarian

compact galaxies, owing to their similar morphological and spectro-

scopic properties.

The Haro galaxies were found at random and by accident. But their

number is so small that they obviously are a very incomplete sample.

A minority of these systems appear to be spiral or peculiar spiral

galaxies seen nearly edge-on and are not included in this study. The









majority can be classified as compact galaxies, because they were dis-

covered in a manner similar to that for the Markarian galaxies, and

because of their morphological and spectroscopic similarities. There-

fore, they can be considered a subset of the Markarian catalog and

considered together with the Markarian galaxies rather than as a

separate group.

Only a limited number of Markarian galaxies were placed on our

list for this study. Mainly, these were systems whose Doppler veloci-

ties were published after 1975. This was done because several neutral

hydrogen studies of Markarian galaxies by other observers were apparently

in progress, and we did not want to duplicate these studies. However,

no other criteria were used in choosing the Markarian galaxies.

Employing these criteria, our initial observing list contained

some 150 Zwicky, Haro, Markarian and Seyfert galaxies. Approximately

1/3 of these systems were not compact galaxies and they are not reported

in this study.

Our sample of compact galaxies can be considered, for the most

part, a subset of the Markarian catalog. A few of our sources were

red objects without Markarian-like properties, but these were mostly

undetected in HI. As this study represents only a selected subset of

the Markarian catalog, we must be very careful in applying the statis-

tics found for Markarian galaxies in general. We need to estimate

the fraction of Markarian galaxies that are compact galaxies. The

study of Huchra (1977) showed that approximately half of all Markarian

galaxies may belong in the normal Hubble sequence, mostly as late type

systems. Most of the remaining Markarian galaxies can be classified

as compact galaxies. Thus perhaps half of all Markarian galaxies are









compact galaxies. On the original list of 150 sources, 24 were selected

only because they were Markarian galaxies (36 other Markarian galaxies

were selected because they were also Zwicky, Haro, or Seyfert galaxies).

Of these, we have classified 16 as compact and 8 as noncompact. Thus,

the estimate that half of all Markarian galaxies are compact is probably

not an overestimate. Indeed, the low luminosity, dwarf systems in the

Markarian catalog may all be compact systems.

The Markarian catalog appears to be substantially complete down to

an apparent photographic magnitude of -15.5 (Sargent, 1972). The pro-

portion of all galaxies that are of the UV intense, Flarkarian type has

been estimated in three studies. Sargent (1972) finds this proportion

to be -2.5% for -22 < M < -20; -7% for Mp = -17; and perhaps as high

as 10% for M = -14. Huchra and Sargent (1973) find this proportion

to be 5-10% for -22 < M < -14. Huchra (1977) finds it to be -6% for

-21 < M < -14. Huchra (1977) included Seyfert galaxies in his es-

timate while the first two studies did not. There is a lot of uncer-

tainty at the low luminosity end. Huchra and Sargent (1973) point out

that the statistics for low luminosity systems is rather poorly known

for both field galaxies and Markarian galaxies.

The majority of the Markarian galaxies are not extremely blue sys-

tems. In the color-color diagram, approximately 75% of the Markarian

galaxies overlap the colors of field galaxies (Huchra, 1977). Thus,

only -1/4 of the Markarian galaxies are exceptionally blue systems.

Huchra (1977) made a rough estimate of the space density of galaxies

as a function of their colors. For (U-B) 5 -0.4 and (B-V) < +0.35, it

seems that over half of all galaxies are Markarian galaxies. Thus, the

Markarian lists seem to be fairly complete for the bluest systems, but









probably less complete towards the redder systems. This bias must be

present among the objects in our study and is probably accentuated owing

to the method by which the objects were chosen. Thus, we expect the

ratio of very blue to blue compact galaxies in this study to be greater

than the actual ratio of these systems.

We can make rough estimates of the proportion of all galaxies

which are blue or very blue compact systems. Overall, it is perhaps

1-5%. For -22 < M < -20, it is -1-3%; for M = -17, it is -2-4%;

and for Mp = -14, it is -3-10%.

Our sample of blue compact galaxies is a magnitude limited sample.

The Markarian catalog is restricted to 13 < M < 17. The Zwicky and

Haro lists have similar, but less well defined limits. In our sample,

only one source is brighter than BT = 13.0 and only one is fainter than

BT = 16.4. This has the effect of producing a strong distance dependency

in the absolute magnitudes. This can be seen in Figure V-l, where we

plot absolute magnitude, MBo, versus log D. The absolute magnitudes
T
must be confined to a band -3-4 magnitudes wide with a slope of -5.

For example, systems of exactly B' = 15.0 would lie along the straight

line defined by MB = -5 log D 10.0. A least squares regression fit

to the data of Figure V-l gives MBg = -4.82 (.27) log D 10.96

(.45).

Thus, nearby, very luminous compacts and distant, intrinsically

faint compacts are excluded from this study. Obviously, the distant,

dwarf systems are too faint to detect. However, might there be any

nearby, very luminous compacts, excluded from our survey, that could

be studied to learn more about the distant systems? Huchra and Sargent

(1973) have estimated the space density of Markarian galaxies. Assuming







































.2

C
C



C
C
C
C
CC
C
C0


CU






'II













-I
II






C1



CI


Figure V-1. Absolute magnitude, MBo, versus the log of the

distance, in Mpc, for blue compact galaxies
distance, in Mpc, for blue compact galaxies.


2.31


C

C


C C


C O
C


L5 G
iLi









that half of the Markarian galaxies are compact, then at M = -22, we

should expect only one blue compact within -50 Mpc. We find none this

luminous in our study. At M = -21, we should expect only one blue

compact within -20 Mpc; at M = -20, we should expect only one within

-12 Mpc; and at M = -19, we should expect only one within -10 Mpc.

Thus, there is a strong selection effect against bright, blue compact

galaxies close to the Milky Way and our list may be deficient by a

very small number of luminous, nearby systems.


Luminosities


Compact galaxies are defined to be systems with higher than average

surface brightnesses. We would like to see how the luminosities and

surface brightnesses of the compact galaxies in our sample compare to

those of more normal galaxies. We first compare their luminosities to

those of the late type galaxies taken from the survey by Shostak (1978).

In Figure V-2, we plot log LBo versus log A. The blue compacts do not
T
extend to as high luminosities or dimensions as the late type. This

difference does not seem to be great. However, the blue compacts do

extend to much lower luminosities than late type galaxies. Late types

appear to have a cutoff in luminosity at LBo 10 L and only -8% in

this sample are fainter than LB = 2 x 10 L. For the blue compacts
T
of our sample, -32% are fainter than LBo = 2 x 109 L and -22% are
9 T
fainter than LBo = 10 L Thus, on the order of 1/3 of the compacts
T
in our sample seem to be dwarf systems.

In the region of overlap in Figure V-2, blue compact galaxies are

somewhat more luminous, on the average, than late type galaxies of

equal dimensions. Least squares regression lines have been fit to the














O


--







a
a

--







a
N










O







Oh

a
C

~L3,

i


23




0
C!


M


LOG P


1.25


Figure V-2. Log LB; as a function of log A. The squares are blue

compact galaxies. The crosses are late type galaxies.
compact galaxies. The crosses are late type galaxies.


++f
-4--





-1i+-














two groups. For the blue compact galaxies, the luminosities are

given by


log L = 1.88 log A + 7.86 V-1
T (.11) (.11)

For late type galaxies, it is given by


log LBo = 1.63 log A + 7.93 V-2
T (.09) (.12)


The difference in the slopes of the two lines appears to be sig-

nificant, considering the uncertainties. On the average then, blue

compact galaxies are more luminous than late type galaxies by a factor

of -1.5 at A = 10 kpc and by a factor of -1.9 at A = 25 kpc.

Next, we consider the surface brightnesses of blue compact galaxies.

Sargent (1970b) found that the surface brightnesses of Zwicky compact

galaxies were -100 times greater than is found in normal Hubble sequence

galaxies. Sargent, however, made the mistake of comparing Holmberg

dimensions for normal galaxies with the dimensions of only the bright

cores of the compact galaxies. These two systems are not compatible.

However, O'Connell (1979), in a study of blue compacts, found that their

average surface brightness was about one magnitude greater than that in

late type galaxies.

A thorough study of surface brightnesses of blue compacts would

determine their central surface brightnesses. Unfortunately, in this

study, we can only find the surface brightnesses averaged over the

total dimensions. This will dilute the effect of the high surface

brightness cores of these objects.








For a measure of the average surface brightness, we divide the

luminosity by the square of the major axis. The log of this is plotted

against color, (B-V)T, in Figure V-3, for blue compacts and for late

type galaxies. Blue compact galaxies are found to be typically bluer

and of higher surface brightnesses than late type galaxies. For 63

blue compacts, the average of their surface brightnesses is 1.998 z 2

times as high as that of the late type galaxies. Among the blue com-

pacts, the highest surface brightnesses are -10 times the average for

late type galaxies.

As approximately 1/3 of our blue compacts are dwarf systems, we

would like to know if the surface luminosities are different for dwarfs

and nondwarfs. The HI masses are an indication of sizes, as will be

seen in the next section. Thus, we plot surface luminosity versus HI

mass for compact systems in Figure V-4. The data for blue compacts are

quite scattered and no correlation is seen. Thus there does not seem

to be any significant difference between dwarf and nondwarf blue

compacts, in terms of their surface luminosities.

Searle et al. (1973) used a model of star bursts to argue that very

luminous galaxies could not be of the extremely blue type, such as the

low metal abundance dwarf systems. The model they used predicted that

at M = -17, the fraction of all galaxies that are extremely blue would

be -10-4, and much smaller at greater luminosities. Thus very blue

systems brighter than M -17 (or Lo = 109 L) should be extremely

rare. However, two of the 11 metal poor systems studied by Alloin et al.

(1978) appear to be of greater luminosities than this limit. The iso-

lated system M162 has a similar metal abundance as IIZw40 but has

Mp -19. A double system, M171, is similar to IZwl8 in metal abundance

but has M = -21.































_. '1
"







c!



C




AT




CD

'-F---.
N

WLC |








Do
5- I



io

C3
C3 1
ml a


0
0


G n
+.3 a +


C- +_+ t' -

,- I t -- -



++

4-


[3-y To


o.eo


O.So


Figure V-3. Log (LBo/A2) as a function of color index, (B-V)'
B- T.
T
The squares are blue compact galaxies. The crosses
are late type galaxies.


nD
a -
CJ-


---


+


;.2






















3
E
a i, =a

"0 C





al M
0
am 3
0
0
0 0
0 -
0 a


9. -0


10.20


11. 0


Log (LBo/A2) as a function of log MHI for blue


compact galaxies.


0
0

On
5
0~
0


0
22


C i
rrJ




















cci








Zt0


L 5. u uC H

LOG M1,


Figure V-4.


, r


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j








To look more deeply at this hypothesis, we plot, in Figure V-5,

log LB0 versus (B-V)T and, in Figure V-6, log LBo versus (U-B)T for blue

compact galaxies and for late type galaxies. For late type galaxies,

it is seen that -2% are bluer than (B-V)T = +0.30, and -15% are bluer

than (B-V)- = +0.40. For blue compacts, we find that -34% are bluer

than (B-V)T = +0.3, and -66% are bluer than (B-V)- = +0.4. Approxi-

mately 1/3 of the blue compacts are bluer than the bluest late type

galaxies in (U-B)T. From Figures V-5 and V-6, it can be seen that the

bluest compacts are dwarf systems, but that extreme blueness is not

limited to the dwarf galaxies. It appears that, of the blue compacts

in our sample brighter than LB = 109 L at least 20% are very blue
Tvr
objects.

From Sargent (1972) and Huchra (1977), it appears that, of all

galaxies brighter than M = -17, on the order of 3-7% are the UV intense,

Markarian types. If half of these are blue compacts and if 20% of

these blue compacts are extremely blue, then on the order of .3-.7%

of all galaxies brighter than Mp = -17 are extremely blue. We must

keep in mind that the Markarian lists may be more complete at the

extremely blue end. Thus, this proportion may actually be as low as

.1 or .2%. This is still considerably greater than the proportion

predicted by Searle et al. (1973). However, this finding does not

invalidate the star burst model. Rather, it indicates that the model

of Searle et al. (1973), of flashes of star formation occurring in

small, statistically independent cells in a galaxy, is not a good

description for the mechanism of the star bursts in these systems.

What is needed is a model which takes into account all of the properties

of these systems and allows star bursts at all luminosities.









0
i3

7:T











o
















,i
O-l



*-n
.-- _







u !u
H:

5921


--
1 -
_+ -
.__
+ + '

a 4- a
a
-I -~
+ -


a
4 5
S -45


0.20
( 3 -/
T


0.10


0. 0


3.30


Figure V-5. Log (LBo) as a function of color index, (B-V)T
T
The square are blue compact galaxies. The crosses
are late type galaxies.


I_
























+


++
-r + -i
+ +
M

f;+


7-m5 1 -C.511
(LI P.I


0. 5


Figure V-6. Log LBo as a function of color index, (U-B)T.
T
The squares are blue compact galaxies. The crosses
are late type galaxies.


-ii



KT




.w]


-0.:5









Neutral Hydrogen Content


We would also like to see how the neutral hydrogen masses of blue

compact galaxies compare to those of late type galaxies. In Figure V-7,

we plot log MHI versus log A. The two groups follow a similar relation-

ship. For the blue compact galaxies, the HI masses are given by


log MI = 1.51 log A + 7.68 V-3
HI (.16) (.12)


For the late type galaxies, they are given by


log MHI = 1.61 log A + 7.43 V-4
(+.07) (.10)


The differences between the two regression lines is slightly less

than significant. The indication is, though not certain, that blue

compact galaxies are more HI rich than late type galaxies of the same

dimensions. A similar result was found by Chamaraux (1977). At A =

6 kpc, the blue compacts contain, on the average, -1.5 times as much

HI as late type galaxies. However, at A = 40 kpc, this is reduced to

a factor of -1.2. We stress that these values are rather uncertain,

but at the least, blue compact galaxies have marginally more neutral

hydrogen for their sizes, than late type galaxies.

As was seen with the luminosities, about 1/3 of the blue compacts

in our sample are dwarf systems. Late type galaxies have a fairly

sharp cutoff at A = 6 kpc. This may, however, be a selection effect

in the classification of low luminosity galaxies. Very few of these

were included in Shostak's (1978) sample, and several of these we

excluded from this discussion because they were classified as peculiar

systems.







89












CD
cc
o



















23


















-r
-L C S






































Figure V-7. Log 11HI as a function of log A. The squares are blue
compact galaxies. The crosses are late type galaxies.
! 2
(-S" -^ -e



2 2


CD

-I -

















Figure V-7. Log MHI as a function of log A. The squares are blue

compact galaxies. The crosses are late type galaxies.








We next consider the HI surface densities of these systems, which

can be represented by dividing the HI mass by the square of the major

axis. In Figure V-8, this is compared with color index, (B-V)T. The

blue compacts can be seen to have significantly greater HI surface

densities than late type galaxies. For 70 of the blue compacts detected

in HI, the average HI surface density is 1.98 z 2 times as high as in

the late type galaxies. The HI surface densities of some of the blue

compacts are much higher than this, up to 12 times the average for

late type systems. This HI surface density does not seem to differ

between dwarf and nondwarf blue compacts. This is seen in Figure V-9,

where HI surface density is compared to luminosity. The HI surface

densities considered here are derived from the optical dimensions of

these systems. Ideally, they should be derived from the HI dimensions,

but these are not easily obtained. In the next section, we shall dis-

cuss the HI dimensions of blue compact galaxies and investigate whether

their true HI surface densities are actually greater than those of late

type galaxies.

As was done for the luminosities, we plot log MHI versus (B-V)T in

Figure V-10 and log MHI versus (U-B)T in Figure V-ll for blue compact

galaxies and late type galaxies. The results are similar to those found

for the luminosities. The bluest systems are seen to have low HI

masses but extreme blueness is not limited to the low HI mass, dwarf

systems.


HI Dimensions


As outlined in the last chapter, the HI masses were corrected for

beamwidth effects by assuming that the HI in these systems was











a

















C-2 _






a a a-


44-
T






























Figure V-8. Log (MI/A2) as a function of color index, (B-V)4
The squares are blue compact galaxies. The crosses
are late type galaxies.
C' I
e V. L (A a f o cojor ie B





























are late type galaxies.













7










C



Sn9

r-
'"oT














+ I
c In

T9
+ -4-
+ 4_


+
n c
'2719 O1 D L IDL. OF =









F igr V-9 Lo (M1/ as a fucto of lo (L^ orbu









BT
CL3 -T + ^ -












FiueV9 og([IA2 a a func ion oflg( O frbu

T













compact galaxies (squares) and for late type
galaxies (crosses).
i +_+-^- T *' +



3~ ~ -r ++ :




o i
'"'.o ~ a .0 i 0n oois o








FigreV- 0 Lo (,,/ )a a f cin. ofo g (L-o) o bu





compact galaxies (squares) and for late type
galaxies (crosses).






















+




+ +





-4- r
o Ci --+--
+ '


+ n -
+ 3 _
7-


-.1







I-rL


0.i 4


0.60


Figure V-10. Log MHI versus color index, (B-V)T, for blue

compact galaxies (squares) and for late type
galaxies (crosses).


0.20
(B


i I


0.30




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