| Title | A spectroscopic study of three rich galaxy clusters at zeta=0.31. |
| Authors | Couch, W. J.; Sharples, R. M. |
| Bibcode | 1987MNRAS.229..423C Search ADS ↗ |
| Abstract | Intermediate-dispersion spectroscopy for 152 galaxies in the fields of three rich galaxy clusters at z of about 0.31 is presented. In each case, the fraction of blue cluster members is a factor of about 5 greater than that predicted on the bases of a morphology-density relation and color distribution appropriate to spirals in nearby clusters. The nature of this blue galaxy excess is investigated using a spectral systhesis technique and diagnostic diagrams based on colors and line strengths. Most of the blue excess arises from systems which have experienced a burst of star formation between 0.1 and 1.5 Gyr prior to the epoch of observation; in the remainder a substantial burst appears to be still in progress. There is no evidence for any increase in the level of normal spirallike star-formation activity in these clusters or in the number of active nuclei. Velocity dispersions and M/L ratios have been determined for each cluster. A comparison of the distribution of populations in the high-z clusters with the morphological segregation observed in the Coma cluster supports the view that the blue galaxies are progenitors of present-day S0s. |
| Objects | 155 Objects Search NED ↙ |
