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Map-based trigonometric parallaxes of open clusters: ComaThis is the fourth study in a series to determine the direct trigonometric parallaxes of four of the nearest open star clusters, the Hyades, the Pleiades, the Praesepe, and the nearby cluster in Coma (Gatewood et al. 1990; Gatewood et al. 1992); Gatewood & Kiewiet de Jonge 1994). The results for the open star cluster in Coma are compared with those of the other three clusters, and the members are found to be significantly subluminous. The trigonometric parallax of the cluster is estimated from that of three members studied with the Multichannel Astrometric Photometer (MAP) at the Thaw Refractor of the University of Pittsburgh's Allegheny Observatory. The weighted mean parallax of the cluster is +13.53 +/- 0.54 mass (0.00054 min), corresponding to a distance modulus of 4.34 +/- 0.09 mag. The U-B excess of the Coma cluster members may be used to adjust the observed absolute magnitudes and the B-V measurements as suggested by Sandage & Eggen (1959). The agreement obtained in this manner suggests that, like subdwarf stars, the stars of the Coma cluster appear subluminous because of line blanketing. One of the three members observed in this study was recognized as a member by its parallax and is the faintest known member of the cluster.
Document ID
19950061687
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Gatewood, George
(Allegheny Observatory, Pittsburgh Univ. Pittsburgh, PA, United States)
Date Acquired
August 16, 2013
Publication Date
June 1, 1995
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 445
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A93286
Funding Number(s)
CONTRACT_GRANT: NSF AST-86-17642
CONTRACT_GRANT: NAG8-253
Distribution Limits
Public
Copyright
Other

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