Journal Article

A New Photometric Study for the Weak-Contact Binary V700 Cygni

Yuan-Gui Yang and Hai-Feng Dai

in Publications of the Astronomical Society of Japan

Volume 61, issue 3, pages 577-584
Published in print June 2009 | ISSN: 0004-6264
Published online June 2009 | e-ISSN: 2053-051X | DOI: https://dx.doi.org/10.1093/pasj/61.3.577
A New Photometric Study for the Weak-Contact Binary V700 Cygni

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We present a new charge-coupled device (CCD) photometry for the weak-contact binary V700 Cygni. From our light curves in the VR bands, a photometric solution was deduced by the 2003 version of the W – D program. The results show that V700 Cyg is a W-subtype binary with [math] [math] 0.5437([math]0.0018) and [math] [math] 15.1%([math]0.3%). The contributions of the third light to the total light are [math] [math] 2.59%([math]0.10%) and [math] [math] 2.64%([math]0.10%) for the VR bands, respectively. Based on all available light-minimum times from 1946 to 2008, a detailed period analysis reveals that there exists a long-term period increase with a periodic oscillation. This cyclic variation, with [math] [math] 54.0([math]2.0)yr, [math] [math] 0.[math]0185 ([math]0.[math]0012 d), and [math] [math] 0.2117([math]0.0059) from equation (3), may result from a light-time effect via the third body, identified by the third light in the photometric solution. If an additional body exists, V700 Cyg may be a triple star system. This kind of tertiary component may remove angular momentum from the central system, which may play an important role in the formation and evolution of the binary. A continuous period increase at a rate of [math] [math] [math]0.33([math]0.08) [math] 10[math]dyr[math] can be interpreted as being mass transfer from the less-massive component to the more-massive one. With mass transferring, the orbital period increases and the separation between both components becomes wider. Finally, the contact configuration will break, as predicted by TRO theory. Therefore, this kind of weak-contact binary with a secular period increase will evolve into a broken-contact configuration.

Keywords: binaries: close; binaries: eclipsing; stars: individual (V700 Cygni)

Journal Article.  4514 words.  Illustrated.

Subjects: Stars

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