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Near-Infrared Observations of the Extremely Red Object Cl 0939+4713B: An Old Galaxy at z ~ 1.58?

Soifer, B. T. and Matthews, K. and Neugebauer, G. and Armus, L. and Cohen, J. G. and Persson, S. E. and Smail, I. (1999) Near-Infrared Observations of the Extremely Red Object Cl 0939+4713B: An Old Galaxy at z ~ 1.58? Astronomical Journal, 118 (5). pp. 2065-2070. ISSN 0004-6256. doi:10.1086/301071.

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Near-infrared imaging and spectroscopic observations of the extremely red object Cl 0939+4713B (R-K ~ 7 mag) have been obtained with the Near Infrared Camera on the Keck I Telescope of the W. M. Keck Observatory. The imaging shows a slightly elongated structure, while the spectroscopy shows a continuum break that allows us to determine a redshift of z = 1.58^(+0.01)_(-0.03) for this system. The fits of a range of models to the infrared spectrum suggest that it is predominantly an old (>10^9 yr) stellar system that suffers little extinction, while the measured R and I magnitudes suggest an age of ~3 × 10^8 yr. The limit on the equivalent width of any emission line in the infrared spectrum suggests that Cl 0939+4713B is not an actively star-forming galaxy. This system, though similar in R-K color to the object HR 10 (also known as J1645+46), is much different in morphology and emission-line strengths, demonstrating the heterogeneity of extremely red extragalactic objects selected on the basis of large R-K values.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Armus, L.0000-0003-3498-2973
Cohen, J. G.0000-0002-8039-4673
Smail, I.0000-0003-3037-257X
Additional Information:© 1999. The American Astronomical Society. Received 1999 March 1. Accepted 1999 August 9. We thank W. Harrision for assistance with the infrared observations, Rob Ivison, Len Cowie, and Amy Barger for obtaining the I image, Marcin Sawicki for helpful discussions, and Dave Thompson for a careful reading of the manuscript and several important suggestions. The W. M. Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Infrared astronomy at the California Institute of Technology is supported by grants from the NSF and NASA. This research has made use of the NASA/IPAC Extragalactic Database, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: distances and redshifts; galaxies: evolution
Issue or Number:5
Record Number:CaltechAUTHORS:20170215-100325608
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Official Citation:B. T. Soifer et al 1999 AJ 118 2065
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74319
Deposited By: Ruth Sustaita
Deposited On:15 Feb 2017 19:56
Last Modified:11 Nov 2021 05:26

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