The Active Chromospheres of Lithium-Rich Red Giant Stars
| Autor: | Christopher Sneden, Melike Afşar, Zeynep Bozkurt, Monika Adamów, Anohita Mallick, Bacham E. Reddy, Steven Janowiecki, Suvrath Mahadevan, Brendan P. Bowler, Keith Hawkins, Karin Lind, Andrea K. Dupree, Joe P. Ninan, Neel Nagarajan, Gamze Böcek Topcu, Cynthia S. Froning, Chad F. Bender, Ryan Terrien, Lawrence W. Ramsey, Gregory N. Mace |
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| Rok vydání: | 2022 |
| Předmět: |
Radial-Velocities
Spectroscopic Survey Kic 9821622 FOS: Physical sciences Astronomy and Astrophysics Mass Astrophysics - Astrophysics of Galaxies Survey Galactic Evolution K-Giant Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Evolved Stars Astrophysics of Galaxies (astro-ph.GA) Chemical-Compositions Abundances Hde 233517 Solar and Stellar Astrophysics (astro-ph.SR) |
| DOI: | 10.48550/arxiv.2209.05941 |
| Popis: | We have gathered near-infrared zyJ-band high-resolution spectra of nearly 300 field red giant stars with known lithium abundances in order to survey their He i lambda 10830 absorption strengths. This transition is an indicator of chromospheric activity and/or mass loss in red giants. The majority of stars in our sample reside in the red clump or red horizontal branch based on their V - J, M ( V ) color-magnitude diagram, and Gaia T (eff) and log(g) values. Most of our target stars are Li-poor in the sense of having normally low Li abundances, defined here as log epsilon(Li) < 1.25. Over 90% of these Li-poor stars have weak lambda 10830 features. However, more than half of the 83 Li-rich stars (log epsilon(Li) > 1.25) have strong lambda 10830 absorptions. These large lambda 10830 lines signal excess chromospheric activity in Li-rich stars; there is almost no indication of significant mass loss. The Li-rich giants may also have a higher binary fraction than Li-poor stars, based on their astrometric data. It appears likely that both residence on the horizontal branch and present or past binary interaction play roles in the significant Li-He connection established in this survey. Texas Advanced Computing Center; NSF [AST-1616040, AST-1908892]; Technological Research Council of Turkey (TUEBITAK) [112T929] We thank Claudia Aguilere-Gomez, Bengt Gustafsson, Noriyuki Matsunaga, George Preston, and our referee for helpful comments on this work. These results are based on observations obtained with the Habitable-zone Planet Finder Spectrograph on the Hobby-Eberly Telescope. We thank the Telescope Operators at the HET for the skillful execution of our observations with HPF. The Hobby-Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universitaet Muenchen, and Georg-August Universitaet Gottingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly. The HET collaboration acknowledges the support and resources from the Texas Advanced Computing Center. We are happy to acknowledge support from NSF grants AST-1616040 (CS), AST-1908892 (GNM), and Technological Research Council of Turkey (TUEBITAK), project No. 112T929 (MA). |
| Databáze: | OpenAIRE |
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