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Luminosities for two yellow supergiants - Nonvariables and the instability stripThe luminosities for two yellow supergiants HD 183864 and Psi And = HD 223047 are determined from the IUE spectra of their hot companions. The absolute magnitudes of HD 183864 and HD 223047 are -2.3 and -2.1 mag, respectively, and their companions have spectral types of A0.0 V and B8.8 V. The companion of Psi And is compatible with the orbital motion tentatively detected by speckle interferometric observations. The supergiant luminosities are combined with the Cepheid luminosities determined in the same way, and also the variables and nonvariables from Schmidt's studies of open clusters. As found by Schmidt, the variable and nonvariable supergiants have almost no overlap in the HR diagram. The combined sample defines the locus of the helium burning blue loops of evolutionary tracks. Because no nonvariables are found to the blue of fainter Cepheids, the observed blue edge of the Cepheid region may be partly determined by the blue loops rather than by the region of pulsational instability.
Document ID
19930051132
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Evans, Nancy R.
(York Univ. North York, Canada)
Date Acquired
August 16, 2013
Publication Date
May 1, 1993
Publication Information
Publication: Astronomical Journal
Volume: 105
Issue: 5
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
93A35129
Funding Number(s)
CONTRACT_GRANT: NAS5-28749
Distribution Limits
Public
Copyright
Other

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