Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-05-15
Astronomy and Astrophysics
Astrophysics
46 pages, 20 figures. Accepted for publication in ApJ. Full text and figures available at http://www.hia.nrc.ca/STAFF/slm/ms16
Scientific paper
10.1086/306309
We discuss the galaxy population of the rich cluster MS1621.5+2640 at z=0.4274, based on spectra and imaging in a field of size 9 arcmin by 23 arcmin (~2 by 5 h**-1 Mpc). The sample comprises 277 galaxies, of which 112 are cluster members, 7 are `near-members', and 47 are field galaxies in the redshift range 0.37<=z<=0.50. The results are analyzed and compared with the z=0.2279 rich cluster Abell 2390. MS1621.5+2640 has a higher blue fraction, a younger stellar population, and is a less evolved cluster. We do not find strong evidence of significant excess star formation compared with the field, although there is a small population of outlying near-members that is unusually blue and that may be affected by the cluster. There is a substantial population of red galaxies with significant Hdelta absorption, which are not easily explained by any simple form of modeled star formation history. We detect two distinct populations of cluster galaxies: those where star formation ceased some time ago, and those with a gradual decrease over many Gyr. Our data suggests that the cluster formed by accretion from the field, with truncation of the star formation beginning at very large radii (>2 times the virial radius). The truncation process does not seem to be a sharp one though, in that lower-luminosity early-type galaxies in the inner core of the cluster are seen with significant Hdelta absorption, indicating some star formation within the last 1-2 Gyr. Some combination of stripping of gas from the outer parts of the galaxy, together with gradual exhaustion of the gas in the inner parts would be consistent with our data.
Abraham Robert G.
Balogh Michael L.
Carlberg Ray G.
Ellingson Erica E.
Hutchings John B.
No associations
LandOfFree
Galaxy Evolution in the z=0.4274 Cluster MS1621.5+2640 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Galaxy Evolution in the z=0.4274 Cluster MS1621.5+2640, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Galaxy Evolution in the z=0.4274 Cluster MS1621.5+2640 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-640568