【摘 要】
：
Two Li-rich candidates,TYC 1338-1410-1 and TYC 2825-596-1,were observed by the new high-resolution echelle spectrograph,LAMOST/ HRS.Based on their high-resoluti
【机 构】
：
CAS Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Scien
论文部分内容阅读
Two Li-rich candidates,TYC 1338-1410-1 and TYC 2825-596-1,were observed by the new high-resolution echelle spectrograph,LAMOST/ HRS.Based on their high-resolution and high-signal-to-noise ratio (SNR) spectra,we derived stellar parameters and abundances of 14 important elements for the two candidates.The stellar parameters and lithium abundances indicate that they are Li-rich K-type giants,and having A(Li)NLTE of 1.77 and 2.91 dex,respectively.Our analysis suggests that TYC 1338-1410-1 is probably a red giant branch (RGB) star at the bump stage,while TYC 2825-596-1 is most likely to be a core helium-burning red clump (RC) star.The line profiles of both spectra indicate that the two Li-rich giants are slow rotators and do not show infrared (IR) excess.We conclude that engulfment is not the lithium enrichment mechanism for either star.The enriched lithium of TYC 1338-1410-1 could be created via the Cameron-Fowler mechanism,while the lithium excess in TYC 2825-596-1 could be associated with either non-canonical mixing processes or He-flash.
其他文献
In this work,we have searched for quasi-periodic oscillations (QPOs) in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Ob
The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest single-dish aperture telescope with a cable-driven parallel robot introduced to
In this work,we studied the variable stars in the open cluster NGC 1912 based on the photometric observations and Gaia DR2 data.More than 3600 CCD frames in B,V
页岩气藏高效开发依赖于高精度三维地震资料,而覆盖密度是决定三维地震资料品质和投资成本的关键参数。针对四川盆地泸州区块海相页岩气三维地震资料,在确保对比因素单一性的前提下,通过抽炮排列将覆盖密度由原始的52.5×104道/km2逐步退化为6种不同覆盖密度的三维观测系统,并对其叠前偏移成果进行定性、定量评价以论证和优选覆盖密度参数;同时对比了相同覆盖密度下大面元高覆盖和小面元低覆盖两种观测系统的优劣。结果表明:①叠前偏移成像效果随着覆盖密度的增大而逐渐改善,信噪比也
The abundancepatterns of r-process-enhanced stars containkey information required to constrain the astrophysical site(s) of r-process nucleosynthesis,and to dee
We report on the discovery of unusual broad absorption lines (BALs) in the bright quasar SDSS J075133.35+134548.3 at z ～ 1,using archival and newly obtained opti
针对南海神狐海域天然气水合物商业化开发计划,研究其开发工程模式十分必要。基于天然气水合物矿藏离岸距离大于300 km,列出两种典型的用于深水油气田开发的全海式开发工程模式。在此基础上,通过天然气水合物采出气与常规天然气田采出气的差异性和生产处理要求的不同,对2种全海式开发工程模式用于天然气水合物开发的适用性进行分析,并对开发工程模式中关键装备的适用性和选型进行了探讨。研究结果表明:①“FPU+FLNG”(浮式生产装置+浮式液化天然气生产储卸装置)的全海式开发工程模式,可以作为未来天然气水合物全海式开发
在非均质性强、地应力差大的页岩气储层,常规段内多簇压裂工艺难以沟通储层中的天然裂缝形成复杂的水力裂缝网络。在四川盆地长宁、威远区块套管井试验了暂堵球分段压裂工艺,通过缩短簇间距、增大单段内的裂缝数目成功地实现了对套变影响段的有效改造,实现了页岩气井控储量的有效动用。为进一歩明确页岩气水平井段内投球暂堵压裂后水力裂缝的扩展规律,建立了投球暂堵压裂二维裂缝延伸模型,分析、总结了投球暂堵压裂过程中的裂缝延伸特征及不同工程参数对裂缝扩展的影响规律。数值模拟结果表明:①簇间距对裂缝扩展有一定的影响,隔簇扩展得到的裂
The influence of wind on the pointing accuracy of large aperture radio telescopes is becoming increasingly serious,especially at high observing frequency.Obtain
We combine K-nearest neighbors (KNN) with a genetic algorithm (GA) for photometric redshift estimation of quasars,short for GeneticKNN,which is a weighted KNN a