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Date and Time of the Query: 2019-07-20 T07:36:30 PDT
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For refcode 1989ApJ...346...34T:
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1989ApJ...346...34T NEAR-INFRARED PHOTOMETRY AND STELLAR POPULATIONS OF FIRST-RANKED GALAXIES IN A COMPLETE SAMPLE OF NEARBY ABELL CLUSTERS TRINH X. THUAN Astronomy Department, University of Virginia AND JEFFERY I. PUSCHELL Titan Systems Received 1988 December 5; accepted 1989 April 29 ABSTRACT Near-infrared JHK magnitudes are presented for 84 brightest cluster members (BCMs) in the complete sample of high Galactic latitude nearby Abell clusters of Hoessel, Gunn, and Thuan. The near-infrared and optical-near-infrared colors are used to investigate the stellar populations in BCMs. There is no radial color gradient in the near-infrared colors. Brighter BCMs have redder (J-K) and (V-K) colors, suggesting a metallicity increase in brighter galaxies. The larger dispersion of their colors implies that BCMs possess more heterogeneous stellar populations than their lower luminosity counterparts, the normal elliptical galaxies, reflecting the variety of evolutionary processes responsible for the formation of BCMs. Special attention is paid to BCMs associated with cooling flows. Those with larger accretion rates have bluer (V-K) colors and are brighter in the visible but not in the infrared. Their (V-K) colors are well correlated with their ultraviolet excesses. These trends suggest that part of the X-ray-emitting cooling gas is converted into high- and intermediate-mass stars emitting in the blue and visible, but not in the infrared. Not all the brightening seen can be attributed to the accretion population because this would produce too blue colors. The radio and H{alpha} emission is not correlated with the colors of the stellar populations. We examine the properties of BCMs as standard candles in the near-infrared and compare them with those in the optical. The dispersions in the BCM absolute magnitudes, corrected for Bautz-Morgan and richness effects, are 0.27 mag in J, 0.25 mag in H, and 0.29 mag in K. A normalization of (M_K_)_0_ = -25.9 at the bright end of the near-infrared Hubble diagram best fits the BCM data. Subject headings: galaxies: clustering - galaxies: photometry - galaxies: stellar content
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