The detection of binary companions to subdwarf B stars ?
نویسنده
چکیده
Intermediate dispersion spectroscopy of a sample of 40 hot subdwarf B stars between 5500 A and 9000 A has been obtained. The sample includes a large fraction of targets which have been studied photometrically. Seven targets show strong lines due to the infrared Ca ii triplet, the unequivocal signature of a cool companion. The positive Ca ii identiications 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.
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تاریخ انتشار 2007