A study of 69 E and SO galaxies located mostly in the field and in groups reveals that the UBV colors become systematically bluer at any given luminosity as the amount of merger-induced fine structure increases. To quantify such fine structure, we define an index-SIGMA that measures ripples, jets of luminous matter, X structures, and boxy isophotes; it ranges between 0 and 7.6 for the above galaxies. The correlations between UBV colors and this index SIGMA closely resemble the correlations found earlier between CN, Mg2, and H-beta line strengths and the same SIGMA. in 36 ellipticals [Schweizer et al. ApJ, 364, L33 (1990)]. Because SIGMA is a rough measure of dynamical youth or rejuvenation, both sets of correlations are most likely due to systematic variations in the mean age of the stellar populations, rather than to variations in their mean metallicity. The new color correlations emphasize that these suggested age variations are not limited to the nuclei, but occur globally in the stellar populations of E and SO galaxies. These correlations also yield a rough ranking of E and SO galaxies by the date of their last major merger event. To calibrate this chronology, we develop a simple two-burst model of evolving stellar populations in mergers and apply it to derive heuristic merger ages (HMA) from UBV colors for each galaxy. These HMAs vary mainly as a function of two parameters: the Hubble type of the premerger components and the gas-to-star conversion efficiency. For representative ranges of these parameters, the HMAs of our 69 E and SO galaxies spread over at least 5 Gyr and up to 10 Gyr. Hence the scatter in color-magnitude relations-though relatively small-is fully compatible with the hypothesis that in the field such galaxies formed, or were seriously modified, by major mergers during at least 1/3 to 2/3 the age of the Universe. A mean HMA of approximately 8 Gyr is suggested for E's with no fine structure and 4.6 Gyr for those with the most fine structure. Good candidates for dynamically young ellipticals having formed through mergers of disk galaxies during the last 7 Gyr are NGC 3610, 1700, 4125, 4915, and 5322; significant rejuvenation seems to have occurred also in NGC 596, 3640, and 5018.

We report 2".4 resolution interferometric observations of the CO emission in the merger galaxy NGC 7252. The molecular gas concentration around the nucleus of this galaxy is well resolved and shows solid body rotation in a direction opposite to the motion of the ionized gas in the outer parts of the galaxy. The CO surface brightness distribution is complex, yet the kinematics of the molecular gas bears striking resemblance to that of the inner ionized gas disk. The CO can be traced farther into the galactic center than the H-alpha emission, but a small central hole (approximately 300 pc radius) apparently free of gas remains. At larger radii, there is a gap between the molecular gas disk and the outlying atomic gas found in H I maps. The molecular gas observations are discussed in light of recent numerical simulations showing the formation of a kinematically decoupled gas concentration at the center of a merger remnant. Details of the gas distribution as a function of radius may have been produced by powerful winds generated in the active star-forming phase of the recent past. Based on these observations, we suggest that NGC 7252 is well on its way to becoming an elliptical with a counterrotating stellar core.