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 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:
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RA (2000) DE Name
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09 42.8 +47 00 Cl 0939+479 = ACO 851
00 18.5 +16 26 Cl 0016+161
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File Summary:
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FileName Lrecl Records Explanations
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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
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Byte-by-byte Description of file: table4 table5
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Bytes Format Units Label Explanations
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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
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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
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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