THE PHOTOMETRIC STUDY OF A NEGLECTED NEAR CONTACT BINARY: BS VULPECULAE

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Publikace nespadá pod Pedagogickou fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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ZHU Liying ZEJDA Miloslav MIKULÁŠEK Zdeněk LIŠKA Jiří QIAN Shengbang VILLIERS DE S.N.

Rok publikování 2012
Druh Článek v odborném periodiku
Časopis / Zdroj Astronomical Journal
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.1088/0004-6256/144/2/37
Obor Astronomie a nebeská mechanika, astrofyzika
Klíčová slova binaries: eclipsing; stars: evolution; stars: individual (BS Vul)
Popis We present a detailed study of the close eclipsing binary BS Vulpeculae. Although it is relatively bright (V: 10.9-11.6 mag) and belongs to short-periodic variable stars (P = 0.48 days), it is rather neglected. To perform a thorough period analysis, we collected all available photometric observations that span the time interval of 1898-2010. Observations include archive photographic plate measurements and visually determined eclipse minima timings done in 1979-2003, which were later shown to be biased to accommodate the existing linear ephemeris. Applying our own direct period analysis we found a well-defined shortening of the orbital period of dP/dt = -6.70(17) x 10(-11) = -2.11(6) ms yr(-1), which implies a continual mass flow from the primary to the secondary component. Using the 2003 version of the Wilson-Van Hamme code, our new complete BV(IR)(C) light curves were analyzed and the physical parameters of the system were derived. We found that BS Vul is a near contact binary system with the primary component filling its critical Roche lobe. The luminosity enhancement on the left shoulder of the secondary minimum shown in the light curves can be explained as a result of a persistent hot spot on the secondary due to the mass transfer from the primary component to the secondary one and heating the facing hemisphere of the secondary component, which is consistent with our result of period analysis. With the period decrease, BS Vul will evolve toward the contact phase. It is another good observational example as predicted by the theory of thermal relaxation oscillations.
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