Stellar population and evolution of galaxies in groups: the NGC2300 group

Abstract

Using panoramic and long-slit spectroscopy at the 6-m telescope of SAO RAS, we studied the stellar population and kinematics of five early-type disc galaxies—members of the NGC2300 group. The evolution of galaxies appears to be absolutely out of synch: while the average age of the stars in the central regions of the galaxies located close to the center of the group ranges from 2 to 7 Gyr, the peripheral spiral galaxies have old nuclei and bulges, with the ages of 10–15 Gyr. The brightest galaxy of the NGC2300 group, which up to now has been considered to be lenticular, of the SA0 type, turned out to be extremely hot dynamically: its bulge rotates slowly, v/σ = 0.06, and the outer parts do not rotate at all.We conclude that the kinematics of the stellar component of NGC2300 indicates that it is not a disc galaxy, but a triaxial spheroid.