Orbital Period Variations And Photometric Study Of Shallow-Contact Binaries:CN And And V737 Per

Shallow-Contact binary is a type of close binary with two components filling their critical Roche Lobes and the degree of contact is smaller than 20%.They are a bridge to connect the detached binaries with the overcontact ones.Their photometric and orbital period investigations have an important theoretical significance for understanding the structures and evolutions of close binaries.In this thesis,we investigated the orbital period variations for two shallow-contact binaries,CN And and V737 Per.Also,a photometric study for V737 Per was performed.Some results have been obtained as follows.1.Based on all available times of light minimum,we investigated the orbital period variation of CN And.The results indicate that its orbital period is undergoing a complex changes combining a long-term decrease with a small-amplitude cyclic oscillation.The secular period decrease is caused by a combination of mass transfer and angular momentum loss due to magnetic braking.The periodic variation should be originated from the light-time effect of the third body.2.The photometric study of the eclipsing binary V737 Per suggested that it is an A-type,shallow-contact binary with a mass ratio of 0.41 and a degree of contact of 8.73%.Our photometric solution indicated that the asymmetry of the light curves can be explained by a cool spot on the surface of the secondary component.In addition,we estimated the absolute parameters of V737 Per and discuss its evolutionary status.The results imply that the primary of V737 Per has evolved away from the zero age main sequence.