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Advances in Astronomy
Volume 2016, Article ID 7468976, 6 pages
http://dx.doi.org/10.1155/2016/7468976
Research Article

The Photometric Investigation of V921 Her Using the Lunar-Based Ultraviolet Telescope of Chang’e-3 Mission

1Yunnan Observatories, Chinese Academy of Sciences (CAS), P.O. Box 110, Kunming 650216, China
2Key Laboratory of the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, P.O. Box 110, Kunming 650216, China
3University of Chinese Academy of Sciences, Yuquan Road No. 19, Sijingshang Block, Beijing 100049, China

Received 6 January 2016; Accepted 17 May 2016

Academic Editor: Alberto J. Castro-Tirado

Copyright © 2016 Xiao Zhou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The light curve of V921 Her in ultraviolet band observed by the Lunar-based Ultraviolet Telescope (LUT) is analyzed by the Wilson-Devinney code. Our solutions conclude that V921 Her is an early type marginal contact binary system with an additional close-in component. The binary system is under poor thermal contact with a temperature difference of nearly 700 K between the two components. The close-in component contributes about 19% of the total luminosity in the triple system. Combining the radial velocity study together with our photometric solutions, the mass of the primary star and secondary one is calculated to be , . The evolutionary scenario of V921 Her is discussed. All times of light minimum of V921 Her available in the bibliography are taken into account and the curve is analyzed for the first time. The most probable fitting results are discussed in the paper, which also confirm the existence of a third component ( year) around the binary system. The period of V921 Her is also undergoing a continuously rapid increase at a rate of , which may be due to mass transfer from the less massive component to the more massive one.