The abundance patterns of r-process-enhanced stars contain key information required to constrain the astrophysical site(s)of r-process nucleosynthesis,and to deepen our understanding of the chemical evolution of our G...The abundance patterns of r-process-enhanced stars contain key information required to constrain the astrophysical site(s)of r-process nucleosynthesis,and to deepen our understanding of the chemical evolution of our Galaxy.To expand the sample of known r-process-enhanced stars,we have developed a method to search for candidates in the LAMOST medium-resolution(R7500)spectroscopic survey by matching the observed spectra to synthetic templates around the EuⅡline at 6645.1 A.We obtain a sample of 13 metal-poor(-2.35<[Fe/H]<-0.91)candidates from 12209 unique stars with 32774 mediumresolution spectra.These candidates will be further studied by high-resolution follow-up observations in the near future.We describe some extensions of this effort to include larger samples of stars,in particular at lower metallicity,using the strength of the BaⅡline at 6496.9 A.展开更多
We report the discovery of two r-process-enhanced stars with [Fe/H]>-0.6 dex selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) survey.Three candidate stars have been selected from ...We report the discovery of two r-process-enhanced stars with [Fe/H]>-0.6 dex selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) survey.Three candidate stars have been selected from the LAMOST medium-resolution(R~ 7500) spectroscopic survey,and the follo wed-up high signal-to-noise ratio and high-resolution(R~31,500) spectra are obtained with the ARC Echelle Spectrograph mounted on the3.5 m telescope at the Apache Point Observatory,which allow us for the determination of stellar atmospheric parameters and abundances of 20 elements.Among these three r-process-enhanced candidate stars,TYC 1710-933-1 and TYC 2858-372-1 have [Eu/Fe] higher than 0.3 dex and [Ba/Eu] lower than 0.0 dex,thus,can be identified as new r-process-enhanced objects.TYC 2858-372-1 shows similar r+s-process pattern to the Sun.TYC 1710-933-1 presents enhancement of the r-process elements of Nd and Eu.Our work indicates that the enrichment mechanisms of the heavy neutron-capture elements are complicated for metal-rich stars.展开更多
基金supported by National Key R&D Program of China(Grant No.2019YFA0405502)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB09-02)+7 种基金the National Natural Science Foundation of China(Grant Nos.11833006,11473033,11603037,11973049,and 11973052)the international partnership program’s key foreign cooperation project,Bureau of International Cooperation,Chinese Academy of Sciences(Grant No.114A32KYSB20160049)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34020205)supported by the Astronomical Big Data Joint Research Center,co-founded by the National Astronomical Observatories,Chinese Academy of Sciences and Alibaba Cloudpartial support for this work from grant PHY 14-30152Physics Frontier Center/JINA Center for the Evolution of the Element(JINA-CEE),awarded by the US National Science Foundationpartially supported by the Open Project Program of the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of SciencesFunding for the project has been provided by the National Development and Reform Commission。
文摘The abundance patterns of r-process-enhanced stars contain key information required to constrain the astrophysical site(s)of r-process nucleosynthesis,and to deepen our understanding of the chemical evolution of our Galaxy.To expand the sample of known r-process-enhanced stars,we have developed a method to search for candidates in the LAMOST medium-resolution(R7500)spectroscopic survey by matching the observed spectra to synthetic templates around the EuⅡline at 6645.1 A.We obtain a sample of 13 metal-poor(-2.35<[Fe/H]<-0.91)candidates from 12209 unique stars with 32774 mediumresolution spectra.These candidates will be further studied by high-resolution follow-up observations in the near future.We describe some extensions of this effort to include larger samples of stars,in particular at lower metallicity,using the strength of the BaⅡline at 6496.9 A.
基金supported by the National Key R&D Program of China No. 2019YFA0405502the National Natural Science Foundation of China under grant Nos. 12090040, 12090044, 11833006, 12022304, 11973052, 11973042 and U2031144+4 种基金the science research grants from the China Manned Space Project with NO.CMS-CSST-2021B05the supports from Youth Innovation Promotion Association (id. 2019060), Chinese Academy of SciencesPhysics Frontier Center/JINA Center for the Evolution of the Element (JINA-CEE), awarded by the US National Science Foundationpartially supported by the Open Project Program of the Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of SciencesGuo Shou Jing Telescope (the Large Sky Area MultiObject 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 Commission。
文摘We report the discovery of two r-process-enhanced stars with [Fe/H]>-0.6 dex selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) survey.Three candidate stars have been selected from the LAMOST medium-resolution(R~ 7500) spectroscopic survey,and the follo wed-up high signal-to-noise ratio and high-resolution(R~31,500) spectra are obtained with the ARC Echelle Spectrograph mounted on the3.5 m telescope at the Apache Point Observatory,which allow us for the determination of stellar atmospheric parameters and abundances of 20 elements.Among these three r-process-enhanced candidate stars,TYC 1710-933-1 and TYC 2858-372-1 have [Eu/Fe] higher than 0.3 dex and [Ba/Eu] lower than 0.0 dex,thus,can be identified as new r-process-enhanced objects.TYC 2858-372-1 shows similar r+s-process pattern to the Sun.TYC 1710-933-1 presents enhancement of the r-process elements of Nd and Eu.Our work indicates that the enrichment mechanisms of the heavy neutron-capture elements are complicated for metal-rich stars.
