Journal Article

The detection of binary companions to subdwarf B stars

C. Simon Jeffery and Don L. Pollacco

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 298, issue 1, pages 179-184
Published in print July 1998 | ISSN: 0035-8711
Published online July 1998 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-8711.1998.01639.x
The detection of binary companions to subdwarf B stars

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Abstract

Intermediate dispersion spectroscopy of a sample of 40 hot subdwarf B stars between 5500 and 9000Å has been obtained. The sample includes a large fraction of targets which have been studied photometrically. Seven targets show strong lines arising from the infrared Ca ii triplet, the unequivocal signature of a cool companion. The positive Ca ii identifications include known photometric binaries and new targets; all are associated with a photometric red excess. Assuming a canonical value for the subdwarf luminosity, all of the detected companions are overluminous compared with the main sequence. The detection procedure indicates an improved and more secure method for the measurement of the binary frequency of hot subdwarfs.

Keywords: binaries: spectroscopic; stars: early-type; subdwarfs

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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