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Author Evans, N. R.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ CEPHEIDS ♦ LUMINOSITY ♦ BINARY STARS ♦ BRIGHTNESS ♦ COMPARATIVE EVALUATIONS ♦ ERRORS ♦ SPECTRA ♦ OPTICAL PROPERTIES ♦ PHYSICAL PROPERTIES ♦ PULSATING VARIABLE STARS ♦ STARS ♦ VARIABLE STARS ♦ Astrophysics & Cosmology- Stars & Quasi-Stellar, Radio & X-Ray Sources
Abstract Luminosities for the classical Cepheids Eta Aql, W Sgr, and SU Cas are determined from IUE spectra of their binary companions. Spectral types of the companions are determined from the spectra by comparison with the spectra of standard stars. The absolute magnitude inferred from these spectral types is used to determine the absolute magnitude of the Cepheid, either directly or from the magnitude difference between the two stars. For the temperature range of the companions (A0 V), distinctions of a quarter of a spectral subclass can be made in the comparison between the companions and standard stars. The absolute magnitudes for Eta Aql and W Sgr agree well with the period-luminosity-color relation of Feast and Walker (1987). Random errors are estimated to be 0.3 mag. SU Cas, however, is overluminous for pulsation in the fundamental mode, implying that it is pulsating in an overtone. 58 refs.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 1991-05-01
Publisher Place United States
Journal Astrophysical Journal
Volume Number 372


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