Synchronous Evolution of Galaxies in Groups: NGC 524 Group
  By means of panoramic spectroscopy at the SAO RAS BTA telescope, we investigated the properties of stellar populations in the central regions of five early-type galaxies -- the NGC 524 group members. The evolution of the central regions of galaxies looks synchronized: the average age of stars in the bulges of all the five galaxies lies in the range of 3--6 Gyr. Four of the five galaxies revealed synchronized bursts of star formation in the nuclei 1--2 Gyr ago. The only galaxy, in which the ages of stellar population in the nucleus and in the bulge coincide (i.e. the nuclear burst of star formation did not take place) is NGC 502, the farthest from the center of the group of all the galaxies studied. 
Olga K. Sil'chenko (1), Victor L. Afanasiev (2) ((1) Sternberg   Astronomical Institute of the Lomonosov Moscow State Univer...
astro-ph.CO