Discovery of a Metal-poor Red Giant Star with the Highest Ultralithium Enhancement
Abstract We present the discovery of 2MASS J05241392−0336543 (hereafter J0524−0336), a very metal-poor ([Fe/H] = −2.43 ± 0.16), highly r -process-enhanced ([Eu/Fe] = +1.34 ± 0.10) Milky Way halo field red giant star, with an ultrahigh Li abundance of A (Li, 3D, NLTE) = 6.15 ± 0.25 and [Li/Fe] = +7.64 ± 0.25, respectively. This makes J0524−0336 the most lithium-enhanced giant star discovered to date. We present a detailed analysis of the star’s atmospheric stellar parameters and chemical abundance determinations. Additionally, we detect indications of infrared excess, as well as observe variable emission in the wings of the H α absorption line across multiple epochs, indicative of a potential enhanced mass-loss event with possible outflows. Our analysis reveals that J0524−0336 lies either between the bump and the tip of the red giant branch (RGB), or on the early asymptotic giant branch (e-AGB). We investigate the possible sources of lithium enrichment in J0524−0336, including both internal and external sources. Based on current models and on the observational evidence we have collected, our study shows that J0524−0336 may be undergoing the so-called lithium flash that is expected to occur in low-mass stars when they reach the RGB bump and/or the e-AGB.
Authors
- Terese T. Hansen (ORCID: https://orcid.org/0000-0001-6154-8983)
- Timothy C. Beers (ORCID: https://orcid.org/0000-0003-4573-6233)
- Jeremy Kowkabany (ORCID: https://orcid.org/0000-0001-9566-4237)
- Erika M. Holmbeck (ORCID: https://orcid.org/0000-0002-5463-6800)
- Ian U. Roederer (ORCID: https://orcid.org/0000-0001-5107-8930)
- C. Charbonnel (ORCID: https://orcid.org/0000-0002-6449-6194)
- Anna Frebel
- Rana Ezzeddine (ORCID: https://orcid.org/0000-0002-8504-8470)
- Vinicius M. Placco (ORCID: https://orcid.org/0000-0003-4479-1265)
- Charli M. Sakari (ORCID: https://orcid.org/0000-0002-5095-4000)
- Yangyang Li (ORCID: https://orcid.org/0000-0002-9953-7929)
- Zoe Hackshaw (ORCID: https://orcid.org/0000-0002-3855-3060)
- Ella Xi Wang (ORCID: https://orcid.org/0000-0001-8493-2873)
Institutions
- University of Geneva (CH)
- Institut de Recherche en Astrophysique et Planétologie (FR)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2024-09-26
- DOI
- https://doi.org/10.3847/1538-4357/ad6004
- Citations
- 4
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 1.33
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- National Computational Infrastructure
- Australian Government
- Joint Institute for Nuclear Astrophysics - Center for the Evolution of the Elements
- European Space Agency
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Nuclear Safety and Security Commission
- Vetenskapsrådet
- Center for Undergraduate Research and Scholarship, Bowling Green State University
- National Cancer Institute
- Astrophysics Division