High amplitude δ Scuti star BO Lyn with evidence of a late A-type companion in an elliptical orbit

摘要

We present 145 times of light maximum for high amplitude δ Scuti star BO Lyn based on several sky surveys(CRTS,DASCH,NSVS,OMC and Super WASP)and our photometric observations.Combining with the data in literature,a total of 179 times of light maximum are used to analyze the O-C diagram of BO Lyn.We find that it can be described by an upward parabolic component and a periodic variation with a period of 34.5±0.1 yr.The latter could be caused by the light travel time effect as a result of an additional companion orbiting in a highly elliptical orbit(e=0.64±0.03).Our study indicates that the companion’s luminosity cannot be ignored,and it should be a late A-type main-sequence star.The long-term period change of BO Lyn is also detected,and its value,1.52±0.26×10^(-3)d Myr^(-1),is consistent with evolutionary models.We suggest that more spectroscopic and photometric observations are needed in the future to confirm the nature of the BO Lyn system.