Stellar activity with LAMOST - I. Spot configuration in Pleiades

	Stellar activity with LAMOST - I. Spot configuration in Pleiades
	Fang, Xiang-Song; Zhao, Gang; Zhao, Jing-Kun; Chen, Yu-Qin; Kumar, Yerra Bharat
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2016-12-01
卷号	463 期号:3 页码:2494-2512
关键词	stars: activity stars: late-type stars: rotation starspots
英文摘要	We use the spectra of Pleiades and field stars from the LAMOST DR2 archive to study how spottedness and activity vary as a function of mass at young ages. We obtained the standard TiOband strength by measuring TiO bands near 7050 angstrom from LAMOST spectra (R approximate to 1800) for a large sample of field GKM dwarfs with solar metallicity. Analysis shows that active dwarfs, including those of late G and early K types, have extra TiO absorption compared to their inactive counterparts, indicating the presence of cool spots on their surface. Active late K and M dwarfs show deeper TiO2 and shallower TiO4 compared to inactive stars at a given TiO5, which could be partly explained through cool spots. We estimated the cool-spot fractional coverage for 304 Pleiades candidates by modelling their TiO2 (and TiO5) band strength with respect to the standard value. The results show that the surfaces of a large fraction of K-and M-type members have very large spot coverage (similar to 50 per cent). We analysed the correlation between spot coverage, rotation and the amplitude of light variation, and found spot coverage on slow rotators (R-o > 0.1) increases with decreasing Rossby number R-o. Interestingly, we detected a saturation-like feature for spot coverage in fast rotators with a saturation level of 40-50 per cent. In addition, the spot distribution in hotter fast rotators is more symmetrical compared to slow rotators. More interestingly, we detected a large spot coverage in many M-type members with no or little light variation. In the bigger picture, these results provide important constraints for the stellar dynamos of these cool active stars.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	LOW-MASS STARS ; DIGITAL SKY SURVEY ; MAIN-SEQUENCE STARS ; CLUSTER NGC 2516 ; M-DWARFS ; ROTATIONAL VELOCITIES ; SPECTROSCOPIC SURVEY ; MAGNETIC ACTIVITY ; DATA RELEASE ; II-PEGASI
收录类别	SCI
语种	英语
WOS记录号	WOS:000393566000018
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/8300]
专题	国家天文台_光学天文研究部
作者单位	Chinese Acad Sci, Natl Astron Observ, Key Lab Opt Astron, Beijing 100012, Peoples R China
推荐引用方式 GB/T 7714	Fang, Xiang-Song,Zhao, Gang,Zhao, Jing-Kun,et al. Stellar activity with LAMOST - I. Spot configuration in Pleiades[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2016,463(3):2494-2512.
APA	Fang, Xiang-Song,Zhao, Gang,Zhao, Jing-Kun,Chen, Yu-Qin,&Kumar, Yerra Bharat.(2016).Stellar activity with LAMOST - I. Spot configuration in Pleiades.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,463(3),2494-2512.
MLA	Fang, Xiang-Song,et al."Stellar activity with LAMOST - I. Spot configuration in Pleiades".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 463.3(2016):2494-2512.