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Optical–infrared studies of the rich cluster of galaxies Abell 370 at z = 0.37

Aragón-Salamanca, Alfonso and Ellis, Richard S. and Sharples, Ray M. (1991) Optical–infrared studies of the rich cluster of galaxies Abell 370 at z = 0.37. Monthly Notices of the Royal Astronomical Society, 248 (1). pp. 128-138. ISSN 0035-8711. doi:10.1093/mnras/248.1.128.

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Using the infrared camera IRCAM on the 3.8-m UK Infrared Telescope we have added new K(≡2−μm) photometry to existing optical CCD measurements for a complete sample of 53 galaxies with K < 17.5 mag in the intermediate-redshift rich cluster Abell 370 (z = 0.37). We demonstrate techniques for processing 2-μm images that achieve flatness to 0.04 per cent and a 1 σ surface-brightness detection limit of μ_K = 21.5) mag arcsec⁻². The mean optical–infrared colour–magnitude relation for early-type galaxies expected to be members on the basis of both spectroscopy and optical colours, is in excellent agreement with that deduced locally when redshift corrections are applied. In contrast to earlier results, we find no evidence for significant galactic reddening in this direction. However, a large proportion (60 per cent) of red members appear to be ≃ 0.1 mag redder in R–K than present-day ellipticals, and a high proportion of these have spectroscopic features indicative of the post-starburst phase. Following earlier suggestions, we examine a model whereby a significant fraction of early-type members suffer short-term bursts of star formation. The red excess found in the colour–magnitude relation of Abell 370 can be explained in terms of a contribution by asymptotic giant-branch stars to the post-burst phase, but the high fraction observed seems to imply that virtually all cluster galaxies must suffer this activity at some point in their evolution.

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Aragón-Salamanca, Alfonso0000-0001-8215-1256
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 1991 Royal Astronomical Society. Provided by the NASA Astrophysics Data System. Accepted: 13 August 1990, Revision received: 09 August 1990, Received in original form: 12 July 1990. The authors thank Dr J. Lucey and Dr M. Fitchett for their help with the study of bimodality and for providing the software to carry out the statistical tests. R. Bower and J. Lucey provided the photometry of Coma galaxies prior to publication the authors also thank Dr A. Pickles for his useful comments. AAS acknowledges the Physics Department of the University of Durham and SERC for financial support.
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Durham UniversityUNSPECIFIED
Science and Engineering Research Council (SERC)UNSPECIFIED
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Official Citation:Alfonso Aragón-Salamanca, Richard S. Ellis, Ray M. Sharples, Optical–infrared studies of the rich cluster of galaxies Abell 370 at z = 0.37, Monthly Notices of the Royal Astronomical Society, Volume 248, Issue 1, January 1991, Pages 128–138,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107828
Deposited By: Rebecca Minjarez
Deposited On:01 Feb 2021 17:00
Last Modified:16 Nov 2021 19:06

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