Astron. Astrophys. Suppl. Ser. 141, 103-111
BVRI imaging of M 51-type pairs
II. Bulge and disk parameters
E. Laurikainen - H. Salo
Send offprint request: E. Laurikainen
Department of Astronomy, University of Oulu, PL 333 90571 Oulu, Finland
e-mail: eija@koivu.oulu.fi
Received September 2; accepted October 8, 1999
Abstract:
We present decompositions of azimuthally averaged surface
brightness profiles in
optical B, V, R and I-bands for a sample of 40 M 51-type
interacting galaxies. The profiles were modelled by an exponential
disk and a spherical bulge described either by the R1/4 law or
by an
exponential function. Half of the galaxies were well fitted by
both bulge models, whereas for
the exponential
function was a better choice. Special care was taken on
eliminating superpositions of the companion galaxies. The mean
B-band central surface brightness
was found to be
,
which is near to the value originally
found by Freeman (1970), but the scatter was
fairly large. Galaxy interactions
have strongly modified the disks in many of the galaxies in the
sample. For example, six of them had extremely flat brightness profiles outside
the exponential part of the disk, and many showed
significant isophotal twists.
Copyright The European Southern Observatory (ESO)
Key words: galaxies -- interactions -- photometry -- fundamental parameters


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