New minima of the short period RS CVn binary system XY UMa taken in 1997-98 follow the light-time orbit with a 30.5 years period. An inferior conjunction of the third body with mass 0.23 [FORMULA] 0.03 [FORMULA] occurred in 1979. It is suggested that the light-curves of XY UMa taken in 1978-79 were affected by the eclipse of the binary system by a dusty envelope of the protostellar object responsible also for the observed infrared excess. There is no correlation between the long-term brightness variations of the system and the minima times in the O-C diagram, so its explanation by the Applegate mechanism proposed recently by Erdem & Güdür (1998) is brought into question.
The RS CVn binary XY UMa as a member of a triple system
BARONE, Fabrizio
1998
Abstract
New minima of the short period RS CVn binary system XY UMa taken in 1997-98 follow the light-time orbit with a 30.5 years period. An inferior conjunction of the third body with mass 0.23 [FORMULA] 0.03 [FORMULA] occurred in 1979. It is suggested that the light-curves of XY UMa taken in 1978-79 were affected by the eclipse of the binary system by a dusty envelope of the protostellar object responsible also for the observed infrared excess. There is no correlation between the long-term brightness variations of the system and the minima times in the O-C diagram, so its explanation by the Applegate mechanism proposed recently by Erdem & Güdür (1998) is brought into question.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
