Discovery of four W UMa type eclipsing binaries in the field of open cluster ASCC 5

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	Discovery of four W UMa type eclipsing binaries in the field of open cluster ASCC 5
	Fang Xiangsong 2; Gu Shenghong 2; Zhang Liyun 1; Pi Qingfeng 1
刊名	Research in Astronomy and Astrophysics
	2013
卷号	13 期号:9 页码:1052
ISSN号	1674-4527
英文摘要	We carried out time-series photometric observations in the Rc -band of the young, poorly studied open cluster ASCC 5 during November and December, 2012, to search for magnetically active stars, and discovered four eclipsing binary stars in this field. In order to characterize these four newly discovered binaries, we derived their orbital periods by their times of light minimum, estimated their effective temperatures based on their (J ? H) colors and analyzed their light curves using the Wilson-Devinney light curve modeling technique. Our analyses reveal that all of them are contact binaries with short orbital periods of less than 0.5 d, with spectral types from late-F to mid-K. Among them, one is a typical A subtype contact binary with a mass ratio around 0.5 and a period of 0.44 d, and one is an H subtype contact binary with a high mass ratio around 0.9 and a short period of about 0.27 d. The other two systems show low amplitudes of light variation (A_(Rc)≤0.11~m); their actual photometric mass ratios could not be determined by the light curve modelings, probably due to their attributes of being partially eclipsing stars. A preliminary analysis for these two systems indicates that both of them are likely to be W subtype contact binaries with low orbital inclinations. In addition, both of these two low amplitude variables show asymmetric distorted light curves (e.g., O'Connell effect of ?R_c? 0.02~m) during the observing runs, suggesting the presence of starspots on these two systems. More interestingly, the one showing a large case of the O'Connell effect presented a remarkable variation in the shape of the light curve on a time scale of one day, indicating that this star is in a very active state. Therefore, these two stars need spectroscopic observations to precisely determine their parameters, as well as further photometric observations to understand the properties of their magnetic activity, e.g., the evolution of starspots.
语种	英语
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/46092]
专题	中国科学院国家天文台
作者单位	1.贵州大学 2.中国科学院国家天文台
推荐引用方式 GB/T 7714	Fang Xiangsong,Gu Shenghong,Zhang Liyun,et al. Discovery of four W UMa type eclipsing binaries in the field of open cluster ASCC 5[J]. Research in Astronomy and Astrophysics,2013,13(9):1052.
APA	Fang Xiangsong,Gu Shenghong,Zhang Liyun,&Pi Qingfeng.(2013).Discovery of four W UMa type eclipsing binaries in the field of open cluster ASCC 5.Research in Astronomy and Astrophysics,13(9),1052.
MLA	Fang Xiangsong,et al."Discovery of four W UMa type eclipsing binaries in the field of open cluster ASCC 5".Research in Astronomy and Astrophysics 13.9(2013):1052.