Issue |
Astron. Astrophys. Suppl. Ser.
Volume 117, Number 2, June I 1996
|
|
---|---|---|
Page(s) | 261 - 280 | |
DOI | https://doi.org/10.1051/aas:1996155 | |
Published online | 15 June 1996 |
Surface photometry of galaxies in low density regions
1
Tartu Observatory, EE2444 Tartu, Estonia, e-mail: vennik@aai.ee
2
Max-Planck-Institut für Astronomie, Königstuhl, D-69117 Heidelberg, Germany e-mail: kuhn@mpia-hd.mpg.de
3
Universitätssternwarte München, Scheiner Str. 1, D-81679 München, Germany e-mail: hopp@usm.uni-muenchen.de
4
Bulgarian Academy of Sciences, Astronomical Institute, Bul. Zarigradsko Shose 72, 1784 Sofia, Bulgaria
Send offprint request to: J. Vennik
Received:
17
August
1995
Accepted:
27
September
1995
We perform detailed surface photometry, based on B- and/or R-band CCD
images of 92 faint galaxies. They are a subsample of those galaxies
which were studied by Hopp et al. (1994) in the direction of three
nearby voids. We derive integral photometric parameters and radial
surface brightness profiles and compare them to those of several faint
galaxy samples, located in different environments, and of a bright
field galaxy sample.
According to the obtained photometric
characteristics, our sample is a mixture of intrinsically bright and
faint galaxies, about 60% of them belonging to the bright subsample
(). These bright ones show mean characteristics of
typical Freeman's disks and are mainly located in the background of
the observed voids. The faint subsample (
) has
parameters typical for the low-surface-brightness (LSB) galaxies.
There are a few well isolated galaxies both among the bright and faint
subsamples. About 40% of studied galaxies reveal ellipticity
and position angle variations along of the radius.
The
colour indices of the observed galaxies span over a wide
range of 0.5-1.8 mag with a median value at 1.11 mag, rather blue.
About 30% of the observed galaxies reveal radial colour gradients at
a 5σ significance level. These
galaxies show typically red centers and are getting bluer towards the
periphery. The most isolated galaxies in our sample
show relatively blue colours (
0.8).
About 40% of the studied galaxies have surface brightness profiles
which can be described by the model of single exponential disk. 38%
of our galaxies have more complicated profiles and either can be
approximated by two exponentials or show the presence of a small bulge. 20%
of the observed galaxies have central light depression and outer
irregularities – typical for some dwarf galaxies. These profile type
frequencies are similar to those of faint field galaxy sample.
The evolutionary history of both the isolated and clustered galaxies
obviously results in similar photometric and structural characteristics.
Thus the photometric methods alone are inadequate for selecting
galaxies with different isolation properties.
Key words: large scale structure of Universe / galaxies: photometry; fundamental parameters; structure
© European Southern Observatory (ESO), 1996