文章基本信息

标题：Magnetic Inflation and Stellar Mass. V. Intensification and Saturation of M-dwarf Absorption Lines with Rossby Number
本地全文：下载
作者：Philip S.Muirhead ; Mark J.Veyette ; Elisabeth R.Newton 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2020
卷号：159
期号：2
页码：742-754
DOI：10.3847/1538-3881/ab5d3d
语种：English
出版社：American Institute of Physics
摘要：In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as Hα, X-ray, and radio emission are known to saturate with low Rossby number (Ro lesssim 0.1), defined as the ratio of rotation period to convective turnover time.The mechanism for the saturation is unclear.In this paper, we use photospheric Ti i and Ca i absorption lines in the Y band to investigate magnetic field strength in M dwarfs for Rossby numbers between 0.01 and 1.0.The equivalent widths of the lines are magnetically enhanced by photospheric spots, a global field, or a combination of the two.The equivalent widths behave qualitatively similar to the chromospheric and coronal indicators: we see increasing equivalent widths (increasing absorption) with decreasing Ro and saturation of the equivalent widths for Ro lesssim 0.1.The majority of M dwarfs in this study are fully convective.The results add to mounting evidence that the magnetic saturation mechanism occurs at or beneath the stellar photosphere.
关键词：M dwarf stars;Stellar rotation;Stellar properties;Stellar activity;Magnetic fields;High resolution spectroscopy;Spectroscopy;Infrared astronomy;Near infrared astronomy