摘要
Radio stars have attracted astronomers＇ attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 （DR2）, published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5＂ and LAMOST objects classified as stars. We calculated the equivalent widths （EWs） of the Ca II H＆K, HS, H＇7, H/3, Ha and Ca II IRT lines by integrating the line profiles. Using the EWs of the Ha line, we detected 147 active stellar spectra of 89 objects having emissions above the Ha continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca II IRT lines. The low value of the EWs542/EWsags ratio for these 14 radio stars possibly alludes to chromospheric plage regions.
Radio stars have attracted astronomers＇ attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 （DR2）, published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5＂ and LAMOST objects classified as stars. We calculated the equivalent widths （EWs） of the Ca II H＆K, HS, H＇7, H/3, Ha and Ca II IRT lines by integrating the line profiles. Using the EWs of the Ha line, we detected 147 active stellar spectra of 89 objects having emissions above the Ha continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca II IRT lines. The low value of the EWs542/EWsags ratio for these 14 radio stars possibly alludes to chromospheric plage regions.
作者
Li-Yun Zhang
Qiang Yue
Hong-Peng Lu
Xian-Ming L.Han
Yong Zhang
Jian-Rong Shi
Yue-Fei Wang
Yong-Hui Hou
Zi-Huang Cao
Li-Yun Zhang Qiang Yue Hong-Peng Lu Xian-Ming L. Han Yong Zhanga Jian-Rong Shi Yue-Fei Wang Yong-Hui Hou(College of Physics/Department of Physics and Astronomy, Guizhou University, Guiyang 550025, China Department of Physics and Astronomy, Butler University, Indianapolis, IN 46208, USA Nanjing Institute of Astronomical Optics ＆ Technology, National Astronomical Observatories, Chinese Academy of Sciences, Nanjing 210042, China Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China)
基金
supported by the Joint Research Fund in Astronomy (U1631236, U1431114, U1631109 and 11263001)
funded by the National Aeronautics and Space Administration and the National Science Foundation
National Major Scientific Project built by CAS
