AAVSO: American Association of Variable Star Observers

CCD Photometry, Period Study, and Light Curve Modeling of the Overcontact Binary Systems NSVS 5374825 and GR Piscium

Volume 50 number 2 (2022)

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Kevin B. Alton
UnderOak Observatory, 70 Summit Avenue, Cedar Knolls, NJ 07927; kbalton@optonline.net

Abstract

During this study precise time-series multi-bandpass (B, V, and Ic) light curve (LC) data for NSVS 5374825 (2018–2019) and GR Psc (2019) were acquired at Desert Blooms Observatory (DBO). Both targets produced new times of minimum which were used along with other eclipse timings mined from the SuperWASP survey and the literature to update their corresponding ephemerides. Preliminary evidence suggests a secular decrease in the orbital period of GR Psc between 2004 and 2019, while during the same time span NSVS 5374825 experienced an increase in its orbital period. Roche modeling to produce synthetic fits to the observed LC data was accomplished using the Wilson-Devinney code. Since each system exhibits a total eclipse, a reliable value for the mass ratio (q) could be determined leading in turn to initial estimates for the physical and geometric elements of both variable systems. Absolute determinations will still require radial velocity and high resolution spectral classification studies.