Bibcode
DOI
Iglesias-Páramo, J.; Vílchez, J. M.
Bibliographical reference
The Astrophysical Journal, Volume 518, Issue 1, pp. 94-102.
Advertised on:
6
1999
Journal
Citations
40
Refereed citations
34
Description
We present the results of a study of the star formation rates (SFRs) of
a sample of disk galaxies in nearby compact groups compared with the
SFRs of a sample of field galaxies. For this purpose, Hα
luminosities and equivalent widths were derived for the galaxies of our
sample. A direct comparison of the equivalent widths and Hα
luminosities, normalized to the B luminosities and estimated area of the
galaxies of both samples, yields the result that the median values of
these quantities are almost identical for both samples, although the
distributions for the compact-group sample are broader around the mean
value than was found in the field galaxy sample. This result can be
explained by assuming that although interactions between galaxies in
compact groups can alter the SFRs, the median value of the normalized
SFRs is preserved, being almost indistinguishable from the corresponding
value for field galaxies. Measuring the global L_Hα/L_B of the
groups, including early-type galaxies, we find that most of the groups
that show the highest level of L_Hα/L_B with respect to a set of
synthetic groups built out of field galaxies show tidal features in at
least one of their members. Finally, we have explored the relationship
between the ratio L_Hα/L_B and several relevant dynamical
parameters of the groups: velocity dispersion, crossing time, radius,
and the mass-to-luminosity ratio, finding no clear correlation. This
suggests that the exact dynamical state of a group does not control the
SFR of the group as a whole. Our results are compatible with a scenario
for compact groups of galaxies in which the dark matter of the group is
arranged in a common halo, therefore preventing a fast collapse of the
galaxies.