Access to Astronomical Catalogues

J/A+AS/118/65       BRI & redshifts in Cl0939+472 & Cl0016+161 (Belloni+, 1996)
Galaxy populations in the distant galaxy clusters.
I. Cl0939+472 (z=0.41) and Cl0016+161 (z=0.54). I.
      Belloni P., Roeser H.-J.
     <Astron. Astrophys. Suppl. Ser. 118, 65 (1996)>
     =1996A&AS..118...65B      (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts

Keywords: galaxies: clusters: Cl 0939+479; Cl 0016+161 -
          galaxies: cluster; redshift; evolution

Abstract:
    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.
Objects:
       ----------------------------------------------------------------------
          RA  (2000)  DE      Name
       ----------------------------------------------------------------------
        09 42.8   +47 00      Cl 0939+479 = ACO 851
        00 18.5   +16 26      Cl 0016+161
       ----------------------------------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table4            71      325   Data of 323 objects with R>22.5mag in
                              Cl 0939+47 field
table5            71      200   Data of 200 objects with R>22.5mag in
                              Cl 0016+161 field


Byte-by-byte Description of file: table4 table5

   Bytes Format Units   Label     Explanations

   1-  3  I3    ---     No        Sequence number
   5- 11  F7.2  arcsec  Xpos      X coordinate
  13- 19  F7.2  arcsec  Ypos      Y coordinate
  21- 25  F5.2  mag     Rmag      R magnitude
  27- 30  F4.2  mag     B-R       ? B-R color
      31  A1    ---     n_B-R     [?] Note no B-R (1)
  32- 35  F4.2  mag     B-I       ? B-I color
      36  A1    ---     n_B-I     [?] Note no B-I (1)
  40- 43  F4.2  ---     D4000     4000A-break index
  45- 50  F6.4  ---     zD92      ? Redshitf from Dressler & Gunn, 1992
  52- 55  F4.2  ---     z         ? Redshift
      56  A1    ---     n_z       [?] Note on z, s = star (1)
  63- 66  F4.2  ---     e_z       ? rms uncertainty on z
      67  A1    ---     nez     [?] Note on e_z (1)
  69- 71  A3    ---     MType     Morphological type

Note (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


References:
   Dressler A. and Gunn J.R.E., 1992, ApJS 78, 1  =Catalog J/ApJS/78/1

Courtesy: Paola Belloni 

(End)                                        Patricia Bauer  [CDS]   12-Apr-1996