近太阳17颗年轻恒星锂丰度: 丽江1.8 m望远镜高色散光谱观测

应用中国科学院云南天文台丽江天文观测站1.8 m望远镜及其折轴光谱仪，对18颗近太阳样本恒星进行了高色散光谱观测，获得这些恒星高质量的高色散光谱。表明原中国科学院国家天文台兴隆观测站2.16 m折轴光谱仪搬迁、改造获得成功，达到并超过了预期的效果。以丽江天文观测站1.8 m望远镜及其折轴光谱仪观测获得的高质量的高色散光谱为基础，应用高斯拟合方法测量了样本中17颗年轻类太阳恒星锂吸收线的等值宽度，并计算了锂元素丰度。应用Hall给出的经验公式，计算了这些年轻恒星的Ca ⅡΗ和Κ(λ=395.0 nm)辐射强度。讨论了锂元素丰度和表明恒星色球活动的Ca H和K线辐射强度之间的关系。发现锂元素丰度值高的年轻恒星，其Ca H和K线辐射更强。考虑到恒星自转速度随恒星年龄的变化，小质量主序前恒星随着恒星年龄的增加，自转明显的加快；主序恒星随着恒星年龄的增加，自转逐渐变慢。我们的结果支持恒星自转越快，其活动性也就越强，以及色球活动较强的恒星具有高的锂元素丰度值。

Lithium Abundance of 17 Young Nearby Stars :High Resolution Spectrograph Observation with Lijiang 1. 8 m Telescope

A high resolution echelle spectra for a sample of 18 stars ,mainly composed of young solar type stars ,is presented in this paper .Observations of these stars have been carried out with the 1.8 m Optical Telescope located at the Lijiang station of the Yunnan Astronomical Observatories ,Chinese Academy of Science (YAOC) .The high-resolution and high signal-to-noise ra-tio spectra of the observations suggest that the reformation of the Coude Echelle Spectrograph attached to the 2 .16 m telescope at the Xinglong station of the National Astronomical Observatories ,Chinese Academy of Science (NAOC) was successful .Based on these observations ,the LiⅠ λ670.8 nm equivalent widths and the lithium abundances of 17 nearby young stars were derived The empirical relationship for estimating the surface flux in the band pass k3925 to k3975 was applied to compute the CaⅡ emis-sion flux .Using the lithium abundances and the CaⅡ emission flux ,the relationship between the Li abundances and the CaⅡ e-mission flux was investigated .A clear correlation between the lithium abundances and the CaⅡ emission flux is found:as the CaⅡ emission flux became stronger ,the lithium abundance decreases in our sample stars .Taking into account of the main features of the rotational evolution of low-mass stars:on the Pre-Main-Sequence ,low-mass stars appear to spin up rapidly ,and reach very rapid rotation rates at the Zero-Age-Main-Sequence(ZAMS);after ZAMS ,the rotation period of star increase with increas-ing age (spin down) .Our results support the chromospherically active solar-type star has high lithium abundances and the rota-tion-activity relation of young stars .