The detection of binary companions to subdwarf B stars |
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| Authors: | C Simon Jeffery & Don L Pollacco |
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| Institution: | Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland,;Isaac Newton Group, Apartado 321, 38780 Santa Cruz de la Palma, Spain |
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| Abstract: | Intermediate dispersion spectroscopy of a sample of 40 hot subdwarf B stars between 5500 and 9000? 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. |
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| Keywords: | binaries: spectroscopic stars: early-type subdwarfs |
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