Simultaneous CCD Photometry of Two Eclipsing Binary Stars in Pegasus--Part 1: KW Pegasi

Volume 41 number 1 (2013)

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Kevin B. Alton

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

Abstract

The coincidental location of BX Peg and KW Peg in the same field-of-view captured by the primary imaging system at UnderOak Observatory (UO) provided an opportunity to study both variable stars from the same exposures. Herein new findings for the eclipsing binary KW Peg will be presented while those from BX Peg will be discussed in a separate paper (Part 2). KW Peg, described as an “Algol type” eclipsing variable (P = 0.816402 d), is only reported in a single work published over twenty years ago. Photometric data collected in three bandpasses (B, V, and Ic), produced eight new times of minimum for KW Peg. These were used to update the linear ephemeris and further analyze potential changes in orbital periodicity by examining the available history of eclipse timings. In addition, synthetic fitting of light curves by Roche modeling was accomplished with programs employing the Wilson-Devinney code. Results from the present study provide a reasonable case for classifying KW Peg as a short-period RS CVn eclipsing binary rather than Algol-like. The primary star in KW Peg would appear to be a late stage G9V-K0V dwarf whereas the secondary is a slightly cooler K0-K1 companion. The eclipse-timing diagram for KW Peg is quite simple and indicates that, on average, the orbital period for this system has remained fairly constant over the past two decades.