Magnetic activities of two contact binaries in quadruple stellar systems

• Published in: Scientific reports Vol. 15; no. 1; pp. 27202 - 13
• Main Authors: Yang, Yuangui, Wang, Shuang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.07.2025; Nature Publishing Group; Nature Portfolio
• Subjects: 639/33/34; 639/33/34/867; Humanities and Social Sciences; Light; multidisciplinary; Science; Science (multidisciplinary); Space telescopes; Trends
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-025-10772-x

Based on observations from the Transiting Exoplanet Survey Satellite (TESS), we conducted a comprehensive study of two contact binaries, V752 Cen and HT Vir, in 2+2-type hierarchical quadruple stellar systems. TESS continuous light curves (LCs) reveal that exhibits random-walk-like or quasi-periodic variations, whereas , shows small jumps. Using the Wilson–Devinney program, we obtained six sets of photometric solutions to trace the migration and evolution of a cool starspot on the stellar surface. Notably, such spot activity can significantly alter LCs and may even reverse minima depths, as observed around BJD 2459282 for V752 Cen. From the TESS time-series LCs, we determined 529 eclipse timings (ETs). For HT Vir, the residuals of the primary and secondary minima show a strong anti-correlation, indicating the presence of starspots. Based on all available ETs, we constructed curves, which could be described by an upward parabola with the light-time effect (LiTE) induced by a third body. Given the third light of for HT Vir, we estimate the mass of the third body to be . For V752 Cen, the minimum mass of the third body is , suggesting it may be a compact star. Finally, we updated the absolute parameters of the two studied binaries, whose components are normal or slightly evolved main-sequence stars.