%From: Ron Allen [rjallen@stsci.edu]
%Sent: Friday, July 06, 2001 3:49 PM
%To: toolan@stsci.edu
%Subject: Petrosian paper


% "STUDIES OF THE SECOND BYURAKAN SURVEY GALAXIES..."

%		Petrosian et al.
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\hyphenation{small-er mo-le-cu-lar re-sult re-sults inter-fero-me-ter
smooth-er kilo-par-sec con-tra-dict spa-tial stu-dy slight-ly
pro-mi-nent su-per-com-pu-ter ga-la-xy inte-grated pre-sent San-ders}

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\slugcomment{Submitted to the Astronomical Journal, Vol.\ NNN}

\shorttitle{Studies of SBS Galaxies}
\shortauthors{Artashes Petrosian et al.}

\begin{document}

\title{STUDIES OF THE SECOND BYURAKAN SURVEY GALAXIES: \\
I.  MERGERS, INTERACTING SYSTEMS, AND CLOSE PAIRS}

\author{Artashes Petrosian\footnote{Visiting Scientist, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA; artashes@stsci.edu}}
\affil{Byurakan Astrophysical Observatory and Isaac Newton Institute of Chile, Armenian Branch\\
Byurakan 378433, Armenia\\
apetros@bao.sci.am}
\author{Brian McLean, Ron Allen, Claus Leitherer, John MacKenty, and Nino Panagia}
\affil{Space Telescope Science Institute\\
3700 San Martin Drive, Baltimore, MD 21218, USA\\
mclean@stsci.edu, rjallen@stsci.edu, leitherer@stsci.edu, mackenty@stsci.edu, panagia@stsci.edu}


\begin{abstract}

This paper reports on a study of the morphological characteristics of
several samples of galaxies drawn from the 1401 objects which comprise
the Second Byurakan Survey (SBS).  These samples have been chosen to
provide information for studies of the relation between galaxy
interactions and galaxy star formation activity.  Our samples include
110 SBS galaxies in 107 mergers, 58 SBS galaxies in 47 interacting 
systems, 49 SBS galaxies
in 30 close pairs (projected separations $\Delta D \leq 50$ kpc and
radial velocity differences $\Delta V \leq 600$ \kmps).  Data are also
presented for 8~SBS galaxies forming 4~wider pairs ($\Delta D \leq 100$
kpc and $\Delta V \leq 700$ \kmps), and 15 SBS galaxies forming 
5~triplets ($\Delta D \leq 100$ kpc and $\Delta V \leq 900$ \kmps).  Four,
and possibly another 3~SBS galaxies, may be satellites of larger
galaxies.  Finally, 6~other SBS objects are possibly HII regions 
in their host galaxies. 

\end{abstract}

\keywords{galaxies: morphology -- galaxies: interactions -- galaxies:
star formation -- galaxies
\vspace*{.5in}}



\section{Introduction} \label{sec:intro}

Star formation is a local process in galaxies, but it is now well
accepted that different factors can enhance the overall star formation
rate.  In particular, there is convincing evidence that interactions
between galaxies can lead to a large-scale redistribution of gas fueling
extranuclear as well as central star formation and/or AGN activity 
%Kennicutt et al. 1998
\citep[e.g.][]{ken98}.  The evidence comes from statistical studies 
\citep[e.g.][]{kee92},
%(e.g.  Keel\& van Soest 1992), 
as well as from direct observations of
star formation indicators such as H$\alpha$ emission 
\citep[e.g.][]{ken87};
%(e.g.  Kennicutt et al.  1987); 
broad band optical colors 
\citep[e.g.][]{lar78};
%(e.g.  Larson\& Tinsley 1978);
radio-continuum emission 
\citep[e.g.][]{hum87};
%(e.g.  Hummel et al.  1987); 
far-infrared radiation 
\citep[e.g.][]{san96,hec99};
%(e.g.  Sanders\& Mirabel 1996, Heckman 1999); 
and SNe II/Ib events 
\citep{pet95}.
%(Petrosian\& Turatto 1995).  
However, a one-to-one correlation
between galaxy-galaxy interactions and star formation is not obvious. 
Many interacting systems show only modest, or even no, star formation
activity.  It is often claimed that in order to trigger star formation,
pre-existing conditions within the interacting systems as well as their
dynamics and mass distributions all play some role, but most important
is the relation between the dynamical timescale of interaction and the
timescale for starbursts.  Comparison of recently developed numerical
models of interactions 
\citep[e.g.][]{mih96}
%(e.g.  Mihos\& Hernquist 1996) 
and starburst models 
\citep[e.g.][]{lei99}
%(e.g.  Leitherer et al.  1999) 
with the observations 
\citep[e.g.][]{bar00}
%(e.g. Barton et al.  2000) 
leads to the conjecture that only close passages can initiate a starburst. 

To investigate this conjecture further, a larger sample of objects is
required, a sample selected for a high rate of star formation or other
type of activity, and including different types of interacting systems. 
What is the best way to create such a sample? One approach is to build a
morphologically-defined sample of galaxies in different stages of
interaction, and then to study in detail the amount of star formation
and other types of activity in these objects.  The second, ``opposite''
approach is to carry out a survey for star-forming and active galaxies,
and then to examine the state of interaction of those systems.  A
brilliant example of the success of the second approach is the list of
different types of interacting objects discovered among the
ultraluminous infrared galaxies 
\citep[ULIRGs, e.g.][]{san96},
%(ULIRGs, e.g.  Sanders\& Mirabel 1996),
and the conclusion that among ULIRGs the fraction of galaxies in
interaction is very close to 100\% 
\citep[e.g.][]{san88,bor99}.
%(e.g.  Sanders et al.  1988, Borne et al.  1999).  
We shall also adopt this second approach, initially
defining our sample in terms of star-forming or other activity. 

The \textit{First Byurakan Sky Survey} carried out by Markarian and
collaborators (Markarian et~al.\ 1983, and references therein, Markarian
et~al.\ 1989) was the first systematic objective-prism (1.5~degree
objective prism was used) search for objects with strong UV-excess
radiation.  This survey produced a catalog of 1515 objects.  This survey
contained more than 200 AGNs and QSOs, and hundreds of starburst, HII
and blue compact galaxies, and remains a rich source list for such
objects in the local universe.  From this survey a sample of ``merger''
galaxies with double and multiple nuclei was extracted 
\citep{pet78,kor81}
%(Petrosian et al. 1978, Koroviakovsky et al.  1981) 
and studied in more detail 
\citep[e.g.][]{maz93}.
%(e.g. Mazzarella\& Boroson 1993).  
Special attention was given to close pairs of galaxies with Markarian 
components \citep{hei73,hei75,cas76,cas78,kar81,kee92}.
%(Heidmann\& Kalloghlian 1973,
%1975; Casini\& Heidmann 1978; Karachentsev 1981; Keel\& van Soest 1992). 
Many Markarian galaxies are by now well-known interacting systems (for
example Mrk171, 231 and 273) with huge star formation or/and AGN
activity \citep[e.g.][]{alo00}.
%(e.g.  Alonso-Herrero et al.  2000). 

Building on the success of the First Byurakan Survey, the \textit{Second
Byurakan Sky Survey} (hereafter SBS) was conducted 
\citep[][and references therein]{ste94}.
%(Stepanian 1994 and references therein).  
Both the Markarian survey and the SBS have been
carried out with the 1-meter Schmidt telescope of the Byurakan
Observatory in Armenia, but for the SBS the telescope was equipped with
three objective prisms ($1.5^{\circ}$, $3^{\circ}$, and $4^{\circ}$) instead
of only one ($1.5^{\circ}$).  In addition, more sensitive ``baked''
photographic plates were used, reaching a limiting photographic
magnitude of about 19.5, which is $\approx 2.5$ magnitudes fainter than
the Markarian survey limit.  In addition to discovering
peculiar objects with strong UV-excess radiation, the improved
spectral resolution of the wider prisms permitted the identification of
galaxies with moderate and strong emission lines even if the UV-excess
emission was absent.  SBS plates cover the region of sky defined by $7^h
40^m < \alpha < 17^h 15^m$, $49^{\circ} < \delta < 61^{\circ}$, an area
of about 1000 square degrees.  During this survey about 3500 peculiar
objects were catalogued.  Accurate positions of 2978 SBS objects were
recently published \citep{bic00}
%(Bicay et al.  2000) 
from which 1400 are identified as galaxies.  It is this initial list of 
1401 SBS galaxies which forms the basis for our samples. 

Our goal is to establish several samples of galaxies drawn
from the SBS which can illuminate the connection between galaxy activity
and galaxy interaction.  In this paper we present data for SBS galaxies
identified as mergers and interacting systems as well as members of
close pairs.  Data for several wide pairs and triplets consisting
respectively of two and three SBS galaxies are also presented.  We pay
special attention to those SBS objects which may be satellites of
brighter galaxies or HII regions in spiral or irregular galaxies.  
In \S2 of this paper the generation of the database is discussed, and 
the observational material is presented. In the same section we also
describe the criteria we have used for the extraction of our own samples
of mergers, interacting galaxies, and close pairs from the SBS.  Our
samples are then described in more detail in \S 3.  Throughout this
paper we have assumed a value for the Hubble constant of $H_0 = 75 $
\kmps\ Mpc$^{-1}$. 
      
\section{The Data} \label{sec:data}

\subsection{Database for SBS galaxies} \label{subsec:database}

\citet{bic00}
%Bicay et al.  (2000) 
provide the most up-to-date and extensive database
for SBS galaxies, including high-accuracy coordinates, apparent blue
magnitudes, and one cross-identification.  The original SBS lists
\citep{mar83,mar84a,mar84b,mar85,mar86,ste88,ste90}
%(Markarian\& Stepanian 1983, 1984a, 1984b, Markarian et al.  1985, 1986,
%Stepanian et al.  1988, 1990) 
contain 735 extragalactic objects for
which spectral classifications are listed in addition to coordinates,
apparent magnitudes, and diameters.  This spectral classification system
was originally introduced by \citet{mar67}
%Markarian (1967) 
for First Byurakan Survey
objects.  It describes the degree of spatial concentration of the UV
emission as well as its intensity.  Emission regions are classified as
stellar (``s'') or diffuse (``d'') if the half-width of the emission
region on Schmidt plates is $\approx 2''$ or $6'' - 8''$, respectively. 
The intermediate types ``sd'' and ``ds'' were also used.  A number
between 1 and 3 was used to indicate the relative intensity of the UV
emission, with 1 being the strongest UV excess.  The existence of
emission lines in the spectra was marked with ``e'', or with ``e:'' for
uncertain cases. 

In the SBS lists, objects with excess UV radiation have spectral
classifications similar to that of \citet{mar67}.
%Markarian (1967).  
Objects which have no UV excess but with moderate or strong emission lines 
have been classified according to the degree of concentration of their 
continuum radiation.  For convenience the spectral classes have been 
collected and included in our database; unfortunately, not all SBS galaxies 
have had this parameter defined. 

Redshifts for 894 SBS galaxies have been collected from the literature
and from the NASA Extragalactic Database (NED).  Sources for redshifts
of SBS galaxies are the articles of 
\citealt{mls84a,mls84b,lip88,ste91,ste93a,ste93b,ste93c,ste93d,ste00,car97,car98,fal99,thu99,hak00}.
%Markarian et al.  1984a, 1984b, Lipovetsky et al.  1988, Stepanian et al. 1991, 1993a,
%1993b, 1993c, 1993d, 2000, Carrasco et al.  1997, 1998, Falco et al.  1999, Thuan 
%et al.  (1999), and Hakopian\& Balayan 2000. 

For each SBS galaxy our database also includes the morphological class
and the number of neighboring objects in a circle of radius 50~kpc.  We
have also included far infrared data for 329 SBS galaxies. 

\subsection{The Observational Material} \label{subsec:observations}

A morphological study of SBS galaxies as well as the counts of their
neighbors have been carried out on the digitized $F$ and $J$~band images
extracted from photographic plates obtained for the second Palomar
Observatory Sky Survey. These plates were obtained with the Palomar Schmidt
Telescope, and have been digitized by ST~ScI using a modified PDS
microdensitometer with a pixel size of $15 \mu$ ($1.0''$).  Using the
positions published by \citet{bic00},
%Bicay et al.  (2000), 
$10'\times 10'$ regions centered on each SBS galaxy were extracted. 

\subsubsection{The Morphology} \label{subsubsec:morphology}

Since the POSS-II plate material was intended for the measurement of
stellar objects between 12 and 22~mag in blue and between 12 and 21~mag 
in red, it is very suitable for the morphological study of SBS
galaxies, which are typically between 15 and 19~mag.  We have carried
out the classification by using gray-scale displays of the digitized
images and by inspecting isophotal maps; the latter are especially
useful in representing the large dynamic range of the images.  The
morphological classification of each SBS galaxy has been done first on
its red image, and later checked on its blue image.  We classify SBS
galaxies within the sequence E -- S0 -- S -- Im and the extension BCDG
for Blue Compact Dwarf Galaxies \citep{san84}.
%(Sandage\& Binggeli 1984).  
In four cases (SBS0834+518, SBS1050+573, SBS1319+579A, \& B) the SBS 
``galaxies'' are quite possibly giant HII complexes in large galaxies.  
These cases are noted in the database as BCD/HII and discussed later 
in \S3. 

Mergers, interacting systems and close pairs are distinguished as
separate classes of objects according to the following definitions:

\textbf{Merger:} Two or more galaxies are in a common envelope, or the
object has double or multiple nuclei.  For this class the nuclei have
approximately similar brightnesses, and are generally centrally located
relative to the outer and inner isophotes of the galaxy.  Multiple
nuclei are often connected with structural details (spiral arms, jets,
tails, etc.).  Some of these nuclei may be luminous HII regions that do
not necessarily belong to a dynamically-distinct object in a merger.  It
is also possible that, similar to clumpy irregulars \citep[e.g.][]{cas76},
%(Casini\& Heidmann 1976), 
some objects classified as mergers are irregular galaxies with a
large network of giant HII regions.  In some of them a double nuclear
structure may be a consequence of dust lanes in the objects.  More
detailed imaging observations will be required in order to identify such
objects and isolate the real mergers among the total listed. 

\textbf{Galaxies in interaction:} Two or more galaxies seen separately
but apparently connected with tidal features (tails, bridges, loops
etc.).  One or more galaxies in the interacting system can have a
disturbed structure.  Usually an SBS galaxy is one component of an
interacting system, but there are also cases when an entry in the SBS
catalog is the interacting system itself.  Occasionally it is difficult
to distinguish a merger from an interacting system, and mergers and
interacting systems can indeed be classified within the same scheme
\citep[e.g.][]{bor99}.
%(e.g.  Borne et al.  1999).  
Nevertheless, for many cases, it was possible to define a morphological 
class for each of the galaxies forming the interacting system. 

\textbf{Close pairs of galaxies:} A system of two galaxies, with
approximately equal angular sizes (apparent angular sizes differ by less
than a factor of 2) with line-of-sight velocity separation $\Delta V
\leq 600$ \kmps and projected linear separation $\Delta D \leq 50$~kpc. 
No other galaxy of similar angular size is identified inside a circle of
$D \approx 100$~kpc.  Tidal features are usually not observed.  Very
often both components of close pairs are SBS galaxies, but also there
are cases when an SBS object forms a close pair with another, non-SBS
galaxy.  We believe that there is no sharp distinction between interacting 
galaxies and close pairs; in this sense some very close pairs can be 
classified as interacting systems, and some wide interacting systems as 
close pairs.  In some close pairs one of the components is $\geq 2.5$~mag 
fainter than the other; in such cases we probably have a system with the 
primary galaxy and a small satellite \citep[e.g.][]{zar97}.
%(e.g.  Zaritsky et al.  1997). 
 
\subsubsection{Counts of Neighbor Galaxies} \label{subsubsec:neighbor-counts}

Counts of neighboring galaxies were done for all SBS galaxies which have
determined redshifts by projecting a circle of 50~kpc radius on a
$10' \times 10'$ digitized field of each SBS galaxy.  All galaxies
detected within this circle were counted if their angular sizes differed
from that of the SBS galaxy by no more than factor of 2.  The counts of
neighbor galaxies were checked in the 50~kpc circles extracted from both
the $F$ and $J$~band images. 

\subsubsection{The IRAS Faint Source Identifications} \label{subsubsec:IRAS}

The IRAS Faint Source Survey (IRAS FSS) contains faint sources of small 
angular size (including all SBS galaxies) observed in far infrared with 
IRAS.  From this survey, catalogs of faint sources have been constructed, 
such as the FSC2 \citep{mos90}
%(Moshiv et al. 1990) 
which contains 173,044 sources. 

A cross-correlation of the FSC2 and the SBS catalogs carried out by the NED 
team yields 329 correspondences.  The FIR data for these galaxies have been 
included in our database.
 
\section{The Samples} \label{sec:samples}

\subsection{SBS Mergers} \label{subsec:mergers} 

During our morphological survey of SBS galaxies we have identified 107
objects with peculiar structures classified as mergers according to the
criteria described above. The number of SBS galaxies in these objects 
is 110. Any peculiar structure of the merger was
checked on both the red and blue images.  For the galaxies SBS0750+559, 
SBS0751+539, SBS1038+580, SBS1528+491B and SBS1538+531 merger structure 
was determined from the red images only; the blue images of these objects 
are saturated.  Table~\ref{table:mergers} lists SBS mergers; the column 
descriptions are as follows:

\begin{tabular}{cp{4in}}
Column Number & Description \\ \hline
(1) & SBS galaxies names, taken from the \citet{bic00} \\
(2) & Photographic apparent magnitudes m$_{pg}$ of SBS galaxies from
\citet{bic00}. The accuracy is usually $\approx 0.5$ mag \\
(3) & Heliocentric redshifts $z$ of the galaxies collected from
the literature and/or NED \\
(4) & The absolute magnitudes M$_{pg}$ calculated from the expression:
${\rm M}_{pg} = {\rm m}_{pg} - 5\log(z) - 43.01 - 0.24 \csc(b^{II})$ \\
(5) & The SBS Spectral classes (SC) \\
(6) & Results of neighbor counts within a 50 kpc radius circle (N$_n$) \\
(7) & The IRAS FSC2 designations \\
(8)--(11) & The IRAS FSC2 flux densities, $f_i$, in janskys,
at 12, 25, 60 and 100 $\mu$, respectively. When only upper limits are
available these are indicated with ``$<$'' 
\citep[see][for further details]{mos92}\\
%(see Moshir et al. 1992 for further details) \\
(12) & Notes and more cross-identifications for SBS galaxies \\
\end{tabular}

In Figure~\ref{fig:mergers} we have collected grayscale representations 
and the contour diagrams
of the $F$~band images of SBS mergers.  Since the GSCII plates are not
calibrated, the contour levels are in arbitrary units.  The lowest
contour level was chosen at the $\approx 3\sigma$ level of the local
background.  The contour interval is constant, but different in each
case; usually it is between 10--30\% of the local background.  The 
interval was chosen in order to best illustrate both the
inner and outer structure of the galaxy. 

\subsection{SBS Galaxies in Interaction} \label{subsec:interactions}

Fifty-eight SBS galaxies have been classified as objects in interaction
according to the criteria described above.  From these 58~objects, 18~SBS 
galaxies are themselves isolated interacting systems (e.g.\ 
SBS1206+609).  In 11~cases, two SBS galaxies together form interacting
system (e.g.\ SBS1204+591 A \& B).  In the remaining 18~cases the SBS
galaxies form interacting systems with other galaxies (e.g.\ 
SBS0912+599).  Eight SBS galaxies, which are in interaction with other
objects, are themselves mergers (SBS0912+599, SBS0924+554, SBS1123+550, 
SBS1223+570, SBS1305+547, SBS1458+600A, SBS1505+605B, and SBS1551+593B).  
Table~\ref{table:interactings} lists all the 58~SBS galaxies in interaction.  
The first five columns of Table~\ref{table:interactings} contain the same 
information as in Table~\ref{table:mergers}.  Column~6 gives the
SBS galaxy morphology according to the following codes: E~$=-1$, Compact 
object = 0, S0~= 1, S~= 2, Im~= 3, BCD~= 4, Merger~= 5, Interacting system~= 6. 
Columns 7--13 of Table~\ref{table:interactings} are, respectively, the
same as columns 6--12 of Table~\ref{table:mergers}.  Concerning the
IRAS FIR data presented in Table~\ref{table:interactings}; since the IRAS 
resolution was not
adequate to separate galaxies in our SBS interacting systems, the IRAS
FSC2 identifications refer either to the whole interacting system or to
one or both components.  IRAS FSC2 identifications with individual SBS
galaxies are more precise. 

Figure~\ref{fig:interactings} shows grayscale representations and contour 
diagrams of the $F$~band images of SBS galaxies in interaction.  Isophotal 
maps for interacting systems are constructed in the same way as for the 
mergers in Figure~\ref{fig:mergers}. 
 
\subsection{SBS Galaxies in Close Pairs} \label{subsec:pairs}

According to the criteria described in \S\ref{subsubsec:morphology}, 30
close pairs of galaxies in which at least one component is an SBS galaxy
have been identified.  In 19 close pairs both components are SBS
galaxies (e.g.\  SBS0750+603 A \& B).  In the remaining 11~pairs, one
component is an SBS galaxy and a second is a ``normal'' galaxy (e.g.\
pair SBS1055+597 and NGC3470).  In 10~cases, the SBS components of the
pair are themselves mergers (SBS0811+607A, SBS0926+606B,
SBS1000+561, SBS1055+597, SBS1159+516A, SBS1200+589B, SBS1200+589C,
SBS1223+537B, SBS1252+591, and SBS1657+590B).  In 7~cases one of the
components of the pair is at least 2.5~mag fainter than the other (e.g.\
SBS0743+591C and PG021818 with a difference of 3.8~mag), we may have a system
consisting of a primary galaxy with a small satellite.  Table~\ref{table:pairs} 
lists all 30~close pairs of galaxies.  Column~1 of Table~\ref{table:pairs} 
is the serial number of the close pair.  Those pairs which
probably consist of systems with a primary galaxy and a satellite are
marked with ``a''.  Column~2 is the SBS galaxy designation and its
companion name.  Columns~3 and~4 are their photographic magnitudes and
heliocentric redshifts.  For the SBS galaxies, the magnitudes are from
\citet{bic00}
%Bicay et al.\ (2000) 
and the redshifts are from the literature.  For those companions which are 
``normal'' galaxies the magnitudes and redshifts are from NED.  Columns~5--7 
of Table~\ref{table:pairs} contain the same information as columns~4--6 of 
Table~\ref{table:interactings}.  The morphologies of ``normal'' galaxies in
column~7 are from NED.  The columns~8--13 of Table~\ref{table:pairs}, 
respectively, are the same as columns~8--13 of Table~\ref{table:interactings}.  
Figure~\ref{fig:pairs} presents $F$~band images of the close pairs, in which 
at least one component is an SBS galaxy; the SBS components of the pairs are 
marked with their names. 
   
\subsection{Wider Pairs and Triplets of SBS Galaxies} \label{subsec:widepairs}

According to several theoretical and observational studies 
\citep[e.g.][]{ick85,zar97},
%(e.g.\ Icke 1985, Zaritsky et al.\ 1997), 
weak interactions between galaxies are
possible even if the spatial separation between galaxies is not very
small.  Linear separations up to $\approx 400$~kpc and recessional
velocity differences up to 1000 \kmps can still be classed as a (weak)
interaction.  In recent years, several articles have focused on the
impact that weak interactions may have on increasing the star formation
rate in gas-rich galaxies \citep[e.g.][]{rud00,pus01}.
%(e.g.\ Rudnick et al.\ 2000, Pustilnik et al.\ 2001).  
In this respect, pairs and triplets of galaxies where all the
members are SBS galaxies can be of great interest, even if the projected
linear separations between components of these systems are $\sim 100$~kpc 
and the velocity differences are $\approx 1000$ \kmps. 

Table~\ref{table:widepairs} lists 4~pairs of SBS galaxies where the
projected linear distance between the components is less than 100~kpc. 
The greatest velocity difference between components of these pairs is
660 \kmps.  SBS0942+587B is itself a merger in pair \#4.  The columns in
Table~\ref{table:widepairs} are the same as in Table~\ref{table:pairs}. 
Figure~\ref{fig:widepairs} shows the $F$~band images of these four pairs. 

Table~\ref{table:triplets} lists 4 systems of SBS galaxies forming
triplets within a separation distance of 100~kpc.  The largest velocity
difference between members of these triplets is 850 \kmps.  SBS1317+523A
is itself a merger in triplet \#3, and SBS0814+579A is an interacting
system in triplet \#1.  The columns in Table~\ref{table:triplets} are
the same as in Table~\ref{table:pairs}, except that column~1 is the
serial number of the triplet.  Figure~\ref{fig:triplets} shows the 
$F$~band images for these five triplets. 

\subsection{SBS Objects as Satellites or Giant HII Regions of Primary Galaxies}
\label{subsec:HIIregions}

Satellite galaxies, significantly less luminous than their primaries,
provide new possibilities to study the forms of galaxy-galaxy
interactions and their relation with star formation.  It has been
suggested that dwarf companions ``sinking'' into the primary system can
stimulate enhanced star formation activity in large gas-rich galaxies
\citep[e.g.][]{mih94,rud00}.
%(e.g.\ Mihos\& Hernquist 1994, Rudnick et al.\ 2000).  
In addition, owing to their relatively small sizes and masses, satellite 
galaxies can be used as tools to study the dynamics of the primary galaxy 
or system of galaxies.  They can help to determine the dynamical mass of 
the systems and primaries, thereby contributing to an understanding of the
distribution of dark matter in galaxies 
\citep[e.g.][]{zar94,zar97}.
%(e.g.\ Zaritsky\& White 1994, Zaritsky et al.\ 1997).  
A list of such systems could be useful for future studies of the problems 
mentioned above. 

Considering our sample of SBS galaxies in close pairs we note that in 
7~pairs the luminosities of the components differ by more than 2.5~mag. 
Such cases may be considered as a system of a primary galaxy with a
satellite.  A careful inspection of the SBS database reveals 3 more
cases when an SBS galaxy is close ($\Delta D \leq 100$~kpc) to a
brighter non-SBS galaxy, with a brightness difference of more than 
2.5~mag.  In 3 additional cases we have the same apparent situation, but
unfortunately redshifts for the fainter SBS galaxies are not yet
available.  All these cases are collected in Table~\ref{table:satellites}. 

In the First Byurakan Survey 5~Markarian objects were identified (Mrk71,
94, 404, 1039 and 1315) which appear to be giant HII complexes within
larger galaxies or even projected on satellites of the primary galaxy
(e.g.\ Mrk71, 94).  Several studies have been carried out on these
Markarian galaxies, but the focus has been on the primary galaxy and not
the HII complex itself; this has introduced some confusion in the
reference data.  To retain clarity in the present sample we list these
cases separately; Table~\ref{table:satellites} lists 6~cases of
satellites and 5~cases when SBS objects are giant HII complexes, either
within the primary galaxy or possibly satellites projected on the
primary. The columns of Table~\ref{table:satellites} describe the same 
parameters as in Table~\ref{table:pairs}. Figure~\ref{fig:satellites} 
presents $F$~band images for the 7~SBS galaxies which are considered as 
satellites of primaries.  Figure~\ref{fig:hosts} presents $F$~band images 
for the 6~SBS galaxies which are taken to be giant HII complexes within the 
primary hosts or their satellites. 

\section{Summary} \label{sec:summary}

We have created an optical and far infrared database for 1401 galaxies 
from the Second Byurakan Survey \citep{bic00}
% (Bicay et al.\ 2000) 
in order to facilitate detailed studies of specific classes of galaxies.
This database also includes morphologies for all 1401 SBS galaxies determined 
from the digitized $F$ and $J$~band images of the POSS~II.  Our purpose 
in this paper is to define a sample of galaxies with enhanced star 
formation and in different stages of interaction.  Our sample includes 
mergers (110 SBS galaxies in 107 mergers), galaxies in interaction (58 SBS 
galaxies in 47 systems), close pairs 
(49 SBS galaxies in 30 pairs), wider pairs (4~pairs), and triplets 
(6~systems).  We have also identified 13 SBS objects which are possibly
satellites of, or giant HII regions in, brighter host galaxies. 

\acknowledgments

A.R.P.\ acknowledges the hospitality of the Space Telescope Science
Institute during his stay as visiting scientist supported by the
Director's Discretionary Research Fund.  The authors are grateful to 
Sharon Toolan for her assistance in the preparation of the AAS\TeX\ 
version of this paper. This research has made use of
NASA/IPAC Extragalactic Database (NED), which is operated by the Jet
Propulsion Laboratory, California Institute of Technology, under
contract with the National Aeronautics and Space Administration. 
The Digitized Sky Survey was produced at the Space Telescope Science 
Institute under U.S.\ Government grant NAG W-2166. The images of these 
surveys are based on photographic data obtained using the Oschin 
Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope.  
The plates were processed into the present compressed digital form 
with the permission of these institutions. The Second Palomar Observatory 
Sky Survey (POSS-II) was made by the California Institute of Technology 
with funds from the National Science Foundation, the National Aeronautics 
and Space Administration, the National Geographic Society, the Sloan 
Foundation, the Samuel Oschin Foundation, and the Eastman Kodak 
Corporation. The Oschin Schmidt Telescope is operated by the California 
Institute of Technology and Palomar Observatory.

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% Figures to follow. Do just captions first, add plot files later.

\onecolumn % revert to full page width for text

\clearpage

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig1.ps}
\caption {Grayscale representations and the contour diagrams of the $F$~band images of SBS mergers.  North is up, and east is to the left.  The lowest contour level is at the $\approx3\sigma$ level of the local background. The contour interval is constant, but different in each case; usually it is between 10--30\% of the local background. Contour plot axes are labeled in arcseconds. 
\label{fig:mergers}
}
\end{figure}

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig2.ps}
\caption {Grayscale representations and the contour diagrams of the $F$~band images of SBS galaxies in interaction. North is up, and east is to the left.  The lowest contour level is at the $\approx3\sigma$ level of the local background. The contour interval is constant, but different in each case; usually it is between 10--30\% of the local background. Contour plot axes are labeled in arcseconds. \label{fig:interactings}
}
\end{figure}

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig3.ps}
\caption {Grayscale representations of $F$~band images of SBS galaxies in close pairs. North is up, and east is to the left.  Components of the pairs are identified.\label{fig:pairs}
}
\end{figure}

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig4.ps}
\caption {Grayscale representations of $F$~band images of the four pairs of SBS galaxies where the projected linear distance between the components is less than 100 kpc. North is up, and east is to the left.  SBS galaxies are identified.\label{fig:widepairs}
}
\end{figure}

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig5.ps}
\caption {Grayscale representations of the $F$~band images of four systems of SBS galaxies forming triplets within the separation distance of 100 kpc.  North is up, and east is to the left.  SBS galaxies are identified.\label{fig:triplets}
}
\end{figure}

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig6.ps}
\caption {Grayscale representations of the $F$~band images for seven SBS galaxies, which are considered as satellites of primaries. North is up, and east is to the left.  SBS satellite galaxies and their primaries are identified.\label{fig:satellites}
}
\end{figure}

\begin{figure}
%\epsscale{0.8} % this figure is too big
%\plotone{fig6.ps}
\caption {Grayscale representations of the $F$~band images of six SBS galaxies, which are considered as giant HII complexes within the primary host or their satellites. North is up, and east is to the left.  SBS objects and their hosts are identified.\label{fig:hosts}
}
\end{figure}

\dummytable%1
\begin{table}
\label{table:mergers}
\end{table}

\dummytable%2
\begin{table}
\label{table:interactings}
\end{table}

\dummytable%3
\begin{table}
\label{table:pairs}
\end{table}

\dummytable%4
\begin{table}
\label{table:widepairs}
\end{table}

\dummytable%5
\begin{table}
\label{table:triplets}
\end{table}

\dummytable%6
\begin{table}
\label{table:satellites}
\end{table}

\end{document}


