The Photometry And Study Of Two W UMa Type Contact Binaries: LO And And V0339 Com

Due to its unique dumbbell structure,high occultation probability,easy observation and easy access to occultation data,W UMa type contact binary stars have attracted wide attention of astronomical researchers.And with the increasingly advanced photoelectric photometry,CCD photometry and other technologies,astronomical researchers have obtained a lot of observation data,and made rapid progress in the study of the structure,evolution etc.of this type binary stars.On above studies,the photometry and orbital period of two W UMa type contact binary stars,LO And and V0339 Com,are studied.The results are as follows:1.The Wilson-Devinney code is used to simultaneously analyze the multi-band light curves and the radial velocity curves,and corresponding physical parameters are modified.It is shown that LO And is an A-type W UMa type binary with a contacting degree of 32.4%.In addition,the orbital period of the LO And binary system is studied by combining all the eclipse timings obtained from our own observations,and those collected from the literature and calculated from the two surveys(Super WASP and TESS).It is found that the orbital period is undergoing a continuous increase and a periodic oscillation.The former can be explained by the mass transfer from the secondary to the primary star,and the latter can be attributed to the light time effect of the third body.But the magnetic activity still cannot be ruled out.The analysis of its evolution state shows that LO And is an unevolved contact binary,which is undergoing thermal relaxation oscillation.2.We conducted the first photometric study on V0339 Com,and the observed light curves show a significant O'Connell effect.The solutions of Wilson-Devinney code show that there may be a cool spot on the surface of the secondary star.Meanwhile,we investigate the orbital period of V0339 Com with eclipse timings obtained from our own observations,and those collected from the literature and calculated by using data of Super WASP,CRTS,ASAS-SN and NSVS surveys.It was found that the orbital period of V0339 Com is undergoing a continuous increase with a rate of d P/dt=5.50 27 10 d ? yr.The absolute physical parameters of V0339 Com are estimated by empirical formulas and its evolution state is also discussed.We inferred that V0339 Com may be located just at the marginal contact state predicted by the TRO theory,and may evolve from the current shallow-contact state to a semi-detached or detached state.