摘要
We utilize the PAdova and TRieste Stellar Evolution Code(PARSEC) combined with photometric observations to determine a guaranteed mass of AL Cas and re-examine its related physical parameters.Multicolor-photometric observations of AL Cas have been performed in 2016 and 2017. We use the WilsonDevinney(W-D) code to analyze the light curves and find that AL Cas is probably an A-subtype contact binary(f = 35.7±0.9%) with a mass ratio q = 0.6399±0.0230 and an effective temperature difference?T = 78 K. The mass-radius relation of a higher luminosity component for AL Cas is obtained by two methods: depending on calculation of the Roche lobe(DCRL method) and depending on calculation of the W-D code(DCWD method). Using this relationship with the PARSEC model, we investigate the component masses of AL Cas as M1 = 1.19±0.23 M⊙ with M2 = 0.76±0.18 M⊙ by the DCRL method and M1 = 1.22±0.26 M⊙ with M2 = 0.78±0.20 M ⊙ by the DCWD method. By means of the photometric studies, we examine the related physical properties of AL Cas with the latest findings. We update the orbital period(Porb = 0.50055593 d) of AL Cas according to six new times of light minimum together with those collected from the literature. Meanwhile, the(O-C)2 curve analysis suggests that the orbital period of AL Cas has a cyclic variation with a period of 81.25 yr and an amplitude of 0.01415 d. This cyclic change would be caused by the light-travel time effect from a third body. A similar mass of the third body(M3 sin i′= 0.279 M⊙) is derived from our two methods.
We utilize the PAdova and TRieste Stellar Evolution Code（PARSEC） combined with photometric observations to determine a guaranteed mass of AL Cas and re-examine its related physical parameters.Multicolor-photometric observations of AL Cas have been performed in 2016 and 2017. We use the WilsonDevinney（W-D） code to analyze the light curves and find that AL Cas is probably an A-subtype contact binary（f = 35.7±0.9%） with a mass ratio q = 0.6399±0.0230 and an effective temperature difference?T = 78 K. The mass-radius relation of a higher luminosity component for AL Cas is obtained by two methods: depending on calculation of the Roche lobe（DCRL method） and depending on calculation of the W-D code（DCWD method）. Using this relationship with the PARSEC model, we investigate the component masses of AL Cas as M1 = 1.19±0.23 M⊙ with M2 = 0.76±0.18 M⊙ by the DCRL method and M1 = 1.22±0.26 M⊙ with M2 = 0.78±0.20 M ⊙ by the DCWD method. By means of the photometric studies, we examine the related physical properties of AL Cas with the latest findings. We update the orbital period（Porb = 0.50055593 d） of AL Cas according to six new times of light minimum together with those collected from the literature. Meanwhile, the（O-C）2 curve analysis suggests that the orbital period of AL Cas has a cyclic variation with a period of 81.25 yr and an amplitude of 0.01415 d. This cyclic change would be caused by the light-travel time effect from a third body. A similar mass of the third body（M3 sin i′= 0.279 M⊙） is derived from our two methods.
基金
supported by the program of the Light in China’s Western Region (LCWR,Grant No. 2015-XBQN-A-02)
the National Natural Science Foundation of China (Grant Nos. 11273051, 11661161016, 11473024 and 11863005)
the 13th Fiveyear Information Plan of Chinese Academy of Sciences (Grant No. XXH13503-03-107)
the Youth Innovation Promotion Association CAS (Grant No. 2018080)
