Eccentric Eclipsing Binaries with Rapid Apsidal Motion: V381 Cas, V796 Cyg, and V871 Per

Abstract V381 Cas, V796 Cyg, and V871 Per are eccentric eclipsing binary systems exhibiting rapid apsidal motion. In this study, their light curves were analyzed for the first time using high-precision photometric data obtained from TESS observations. The photometric mass ratios were derived as q = 0.9294 ± 0.0007 for V381 Cas, q = 0.8146 ± 0.0030 for V796 Cyg, and q = 0.8854 ± 0.0027 for V871 Per. The ( O – C ) analyses were conducted by combining newly derived eclipse timings from TESS data with previously published minima. From these analyses, the apsidal motion periods were determined to be 20.45 ± 0.19 yr for V381 Cas, 32.55 ± 0.34 yr for V796 Cyg, and 70.80 ± 3.98 yr for V871 Per. Absolute parameters of the stellar components were also estimated. The masses of the components were calculated as follows: for V381 Cas, M 1 = 2.06 ± 0.37, M ⊙ and M 2 = 1.92 ± 0.37, M ⊙ ; for V796 Cyg, M 1 = 3.31 ± 0.20, M ⊙ and M 2 = 2.70 ± 0.20, M ⊙ ; and for V871 Per, M 1 = 1.05 ± 0.14, M ⊙ and M 2 = 0.93 ± 0.14, M ⊙ . Furthermore, apsidal motion parameters were evaluated using both observational and theoretical internal structure constants ( log k ¯ 2 , obs and log k ¯ 2 , theo ). The relative contribution to the total apsidal motion rate was found to be less than 3% in all three systems.