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-tonoise ratio(SNR)spectra,we derived st...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-tonoise 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 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.展开更多
To obtain reliable Cu abundances with the APOGEE H-band spectra,it is important to investigate the non-local thermodynamic equilibrium(NLTE)effects on the formation of the H-band Cu I lines.In addition,the Cu atomic m...To obtain reliable Cu abundances with the APOGEE H-band spectra,it is important to investigate the non-local thermodynamic equilibrium(NLTE)effects on the formation of the H-band Cu I lines.In addition,the Cu atomic model needs to be tested.Based on both the high-resolution and high signal-tonoise ratio H-band spectra from the Apache Point Observatory Galactic Evolution Experiment(APOGEE)and optical data,we derived the LTE and NLTE copper abundances of 13 FGK sample stars with the spectral synthesis method.We find that the NLTE effects are negligible for the Cu I 16005.7?A line in the IR H-band.Consistent copper abundances within the uncertainties from these two sets of lines have been obtained,which indicates the reliability of our NLTE copper atomic model.We note that the[Cu/Fe]ratios increase with increasing metallicity when~–1.4 dex<[Fe/H]<~–0.5 dex,favoring a secondary(metallicity-dependent)copper production.展开更多
基金the National Key R&D Program of China(No.2019YFA0405502)the Key Research Program of the Chinese Academy of Sciences under grant No.XDPB09-02+8 种基金the National Natural Science Foundation of China(Grant Nos.11973052,11833006,11473033 and 11603037)the International partnership program’s Key foreign cooperation project,Bureau of International Cooperation,Chinese Academy of Sciences(No.114A32KYSB20160049)supported by the Astronomical Big Data Joint Research Center,co-founded by the National Astronomical Observatories,Chinese Academy of Sciences and Alibaba Cloudpartially supported by the Open Project Program of the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciencesthe financial support from China Scholarship Council(CSC,No.201604910642)for his study at New Mexico State University in the United States of Americathe supports from Youth Innovation Promotion Association,Chinese Academy of SciencesGuo Shou Jing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciences.Funding for the project has been provided by the National Development and Reform Commissionthe NASA/IPAC Infrared Science Archive,which is funded by the National Aeronautics and Space Administrationthe Wide-field Infrared Survey Explorer,which is a joint project of the University of California,Los Angeles,and the Jet Propulsion Laboratory/California Institute of Technology,funded by the National Aeronautics and Space Administration。
文摘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-tonoise 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 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.
基金the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB09-02)the National Key Basic Research Program of China(Grant No.2014CB845700)+3 种基金the National Natural Science Foundation of China(Grant Nos.11833006,11473033,11603037 and 11803049)International partnership program’s Key foreign cooperation project,Bureau of International Cooperation,Chinese Academy of Sciences(Grant No.114A32KYSB20160049)the Astronomical Big Data Joint Research Centerco-founded by the National Astronomical Observatories,Chinese Academy of Sciences and the Alibaba Cloud。
文摘To obtain reliable Cu abundances with the APOGEE H-band spectra,it is important to investigate the non-local thermodynamic equilibrium(NLTE)effects on the formation of the H-band Cu I lines.In addition,the Cu atomic model needs to be tested.Based on both the high-resolution and high signal-tonoise ratio H-band spectra from the Apache Point Observatory Galactic Evolution Experiment(APOGEE)and optical data,we derived the LTE and NLTE copper abundances of 13 FGK sample stars with the spectral synthesis method.We find that the NLTE effects are negligible for the Cu I 16005.7?A line in the IR H-band.Consistent copper abundances within the uncertainties from these two sets of lines have been obtained,which indicates the reliability of our NLTE copper atomic model.We note that the[Cu/Fe]ratios increase with increasing metallicity when~–1.4 dex<[Fe/H]<~–0.5 dex,favoring a secondary(metallicity-dependent)copper production.
