On the discovery of K-enhanced and possibly Mg-depleted stars throughout the Milky Way
Abstract
Stars with unusual elemental abundances offer clues about rare astrophysical events or nucleosynthetic pathways. Stars with significantly depleted magnesium and enhanced potassium ([Mg/Fe] < −0.5; [K/Fe] > 1) have to date only been found in the massive globular cluster NGC 2419 and, to a lesser extent, NGC 2808. The origin of this abundance signature remains unknown, as does the reason for its apparent exclusivity to these two globular clusters. Here we present 112 field stars, identified from 454 180 LAMOST giants, that show significantly enhanced [K/Fe] and possibly depleted [Mg/Fe] abundance ratios. Our sample spans a wide range of metallicities (−1.5 < [Fe/H] < 0.3), yet none show abundance ratios of [K/Fe] or [Mg/Fe] that are as extreme as those observed in NGC 2419. If confirmed, the identified sample of stars represents evidence that the nucleosynthetic process producing the anomalous abundances ratios of [K/Fe] and [Mg/Fe] probably occurs at a wide range of metallicities. This would suggest that pollution scenarios that are limited to early epochs (such as Population III supernovae) are an unlikely explanation, although they cannot be ruled out entirely. This sample is expected to help guide modelling attempts to explain the origin of the Mg–K abundance signature.
Additional Information
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) Accepted 2018 July 13. Received 2018 July 10; in original form 2018 March 2. We thank David W. Hogg (NYU), and Hans-Walter Rix (MPIA). ARC is supported through an Australian Research Council Discovery Project under grant DP160100637. AYQH is supported by a Fulbright grant through the German-American Fulbright Commission and a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. CAT thanks Churchill College for his fellowship and Monash University for hosting him as a Kevin Westfold distinguished visitor. This research has made use of NASA's Astrophysics Data System. Guoshoujing 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 beenprovided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.Attached Files
Published - sty1915.pdf
Submitted - 1807.05693
Supplemental Material - sty1915_supplemental_files.zip
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Additional details
- Eprint ID
- 89625
- Resolver ID
- CaltechAUTHORS:20180913-133205871
- DP160100637
- Australian Research Council
- German-American Fulbright Commission
- DGE-1144469
- NSF Graduate Research Fellowship
- Churchill College
- National Development and Reform Commission (China)
- Created
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2018-09-13Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field