Stellar populations and galaxy evolution in the NGC 80 group

Abstract

We have studied the central parts of seven early-type galaxies -- the members of the X-ray-bright galaxy group NGC 80 -- by means of integral-field spectroscopy at the Russian 6m telescope. We searched for signatures of synchronous evolution of the group galaxies. The following results have been obtained. Five galaxies have revealed old stellar populations in the bulges, with the SSP-equivalent ages from 10 to 15 Gyr. A moderate-luminous S0 galaxy IC 1548 demonstrates consequences of recent star formation burst: the SSP-equivalent age of the bulge is 3 Gyr, that of the nucleus -- 1.5 Gyr. It is also in this galaxy that we have found a circumnuclear polar gaseous disk which changes smoothly to counterrotating one at radii larger than 3 arcsec(1 kpc). Probably, IC 1548 had suffered an interaction with external gas accretion which might also provoke the central star formation burst. In the giant E0 galaxy NGC 83 which is projected close to the group center but has a line-of-sight velocity redshifted by 600 km/s with respect to the group systemic velocity, we have observed a compact massive stellar-gaseous disk with the radius of some 2 kpc demonstrating current star formation. Consequently, NGC 83, just as IC 1548, has the young stellar population in the center. We speculate that a small subgroup leaded by NGC 83 is in process of infalling into the old massive group around NGC 80.