CaII H&K emission distribution of ∼ 120 000 F, G and K stars in LAMOST DR1. (August 2015)

• Record Type: Journal Article
• Authors: Zhao, Jing-Kun; Oswalt, Terry D.; Chen, Yu-Qin; Shi, Jian-Rong; Tan, Ke-Feng; Fang, Xiang-Song; Zhao, Gang; Yang, Ming; Zhang, Yong; Hou, Yong-Hui; Wang, Yue-Fei
• Is Part Of: Research in astronomy and astrophysics. Volume 15:Number 8(2015:Aug.)
• Page Start: 1282
• Page End: 1293
• Publication Date: 2015-08
• Subjects: Astronomy -- Periodicals; Astrophysics -- Periodicals; 520.5
• DOI: 10.1088/1674-4527/15/8/013
• Languages: English
• ISSNs: 1674-4527

Abstract

<abstract> <title>Abstract</title> <p>We present chromospheric activity index <italic>S</italic>_HK measurements for 119 995 F, G and K stars with high signal-to-noise ratio (S/N &gt; 80) spectra, extracted from LAMOST DR1 in SDSS <italic>g</italic> band. The index δ<italic>S</italic> for each of these stars is calculated by the difference between its <italic>S</italic>_HK value and the baseline determined from very inactive stars. The effect of metallicity on measurement of δ<italic>S</italic> varies with stellar <italic>T</italic>_eff. No evident Vaughan-Preston gap appears in our sample. The relation between δ<italic>S</italic> and vertical distance from the Galactic plane is determined for stars with <italic>T</italic>_eff &lt; 5500 K. Stars with higher δ<italic>S</italic> tend to be closer to the Galactic plane. Two open clusters in the DR1 sample, M45 and M67, exhibit the expected general trend that δ<italic>S</italic> decays with age. For stars with <italic>T</italic>_eff &gt; 5500 K, similar δ<italic>S</italic> levels appear in both young and old cluster stars, which supports Pace's suggestion that caution should be exercised when deriving the age of a single star by using its chromospheric activity. Finally, we investigate the relation between δ<italic>S</italic> and the kinematics of our sample.</p> </abstract>