J/A+AS/118/65 J/A+AS/118/65 BRI & redshifts in Cl0939+472 & Cl0016+161 P Belloni H -J Roeser Astron. Astrophys. Suppl. Ser. 118 65 1996 1996A&AS..118...65B Clusters, galaxy Redshifts galaxies: clusters: general galaxies: clusters: individual (Cl 0939+479, CI 0016+161) galaxies: distances and redshifts galaxies: evolution We present results of a study of the galaxy population of Cl 0939+472 (z=0.41) and Cl 0016+161 (z=0.54). We have used narrow-band filters (FWHM=~90-200A) and broad band B, R, I filters covering the range from 3800A to 9200A obtain low resolution spectra for all galaxies brighter than R=22.5mag in a 5'x5' (Cl 0939+472) and a 3.5'x5' (Cl 0016+161) field. Template spectra for classical Hubble type and E+A galaxies were fitted to the low-resolution spectral energy distribution in order to determine the galaxies' redshift and the morphological type. We detected 160 cluster members in Cl 0939+472 and 100 in Cl 0016+161, with a success rate of about 80% in the determination of redshifts and corresponding classification of morphological types from spectral energy distributions. These results constitute a statistical improvement of at least a factor of 4 over the most complete study to date of these clusters. In particular, we provide a large sample of elliptical galaxies with secure membership, well suited for a study of evolutionary effects. The same E+A templates developed for the analysis of Cl 0939+472 were successful in recognizing almost all of the spectroscopically already known E+A galaxies in Cl 0016+161 and in identifying 10 new ones. Our results show that in this cluster, too, the fraction of E+A galaxies represents about 20% of the total galaxy population. This outlines the importance of taking into account galaxies with signs of recent star formation for a correct evaluation of the Butcher-Oemler effect in distant galaxy clusters.

Cl 0939+479ACO 85109 42.8 +47 00 Cl 0016+16100 18.5 +16 26

No Sequence number --- Xpos X coordinate arcsec Ypos Y coordinate arcsec Rmag R magnitude mag B-R B-R color mag n_B-R Note no B-R number=1 An '?' indicates objects that could not be fitted by any of the templates at any redshift between z=0.3 and z=0.7 --- B-I B-I color mag n_B-I Note no B-I number=1 An '?' indicates objects that could not be fitted by any of the templates at any redshift between z=0.3 and z=0.7 --- D4000 4000A-break index --- zD92 Redshitf from Dressler & Gunn, 1992 --- z Redshift --- n_z Note on z, s = star number=1 An '?' indicates objects that could not be fitted by any of the templates at any redshift between z=0.3 and z=0.7 --- e_z rms uncertainty on z --- n_e_z Note on e_z number=1 An '?' indicates objects that could not be fitted by any of the templates at any redshift between z=0.3 and z=0.7 --- MType Morphological type --- Patricia Bauer CDS 1996Apr12Paola Belloni <belloni@usm.uni-muenchen.de> J_A+AS_118_65.xml