The detection of binary companions to subdwarf B stars

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