AAVSO: American Association of Variable Star Observers

CCD Photometry, Light Curve Modeling, and Period Study of the Overcontact Binary Systems V647 Virginis and V948 Monocerotis

Volume 47 number 1 (2019)

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Kevin B. Alton
UnderOak Observatory, 70 Summit Avenue, Cedar Knolls, NJ 07927; ail@underoakobservatory.com

Abstract

Prior to this investigation, monochromatic CCD data for V647 Vir and V948 Mon had only been generated from automated surveys which employ sparse sampling strategies. In this study precise multi-color (B, V, and Ic) light curve data for V647 Vir (2018) and V948 Mon (2017–2018) were acquired at Desert Bloom Observatory (DBO). Both targets produced new times of minimum which were used along with other eclipse timings from the literature to update their corresponding ephemerides. Despite the limited amount of published data, preliminary evidence suggests a secular decrease in the orbital period of V948 Mon. Roche modeling to produce synthetic fits to the observed light curve 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.