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Identifying Li-rich giants from low-resolution spectroscopic survey

  • Yerra Bharat Kumar
  • Bacham Eswar Reddy
  • Gang Zhao
Article

Abstract

In this paper we discuss our choice of a large unbiased sample used for the survey of red giant branch stars for finding Li-rich K giants, and the method used for identifying Li-rich candidates using low-resolution spectra. The sample has 2000 giants within a mass range of 0.8 to \(3.0\textit{M}_{\odot }\). Sample stars were selected from the Hipparcos catalogue with colour (B–V) and luminosity \((\textit{L}/\textit{L}_{\odot }\)) in such way that the sample covers RGB evolution from its base towards RGB tip passing through first dredge-up and luminosity bump. Low-resolution (R \(\approx \) 2000, 3500, 5000) spectra were obtained for all sample stars. Using core strength ratios of lines at Li I 6707 Å and its adjacent line Ca I 6717 Å  we successfully identified 15 K giants with A(Li) > 1.5 dex, which are defined as Li-rich K giants. The results demonstrate the usefulness of low-resolution spectra to measure Li abundance and identify Li-rich giants from a large sample of stars in relatively shorter time periods.

Keywords

Stars RGB abundances lithium rich stellar atmospheres spectroscopy. 

Notes

Acknowledgements

We are thankful to the observatory supporting staff at IAO, CREST, and VBO for their help during observations. We thank HTAC and VTAC for allocating sufficient observing time that enabled this survey successful. We also thank the referee for useful comments that improved the presentation of manuscript. We thank Mr Harsha Reddy for his careful reading of the manuscript and suggestions for better reading. Y.B.K. is thankful to Y.-Q. Chen and X.-S. Fang for fruitful discussions. We thank the Chinese Academy of Sciences for supporting this study through CAS PIFI fellowship, and National Natural Science Foundation of China for their partial support under Grant Nos 11550110492, 11390371, 11233004. Y.B.K. thanks the Indian Institute of Astrophysics for supporting the stay during June 2017 while this manuscript was being finalized.

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Copyright information

© Indian Academy of Sciences 2018

Authors and Affiliations

  1. 1.Key Laboratory of Optical Astronomy, National Astronomical ObservatoriesChinese Academy of SciencesBeijingChina
  2. 2.Indian Institute of Astrophysics, KoramangalaBengaluruIndia

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