| Issue |
A&A
Volume 690, October 2024
|
|
|---|---|---|
| Article Number | A139 | |
| Number of page(s) | 8 | |
| Section | Galactic structure, stellar clusters and populations | |
| DOI | https://doi.org/10.1051/0004-6361/202451030 | |
| Published online | 04 October 2024 | |
Multi-iron subpopulations in Liller 1 from high-resolution H-band spectroscopy★
1
INAF, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna,
Via Gobetti 93/3,
40129
Bologna,
Italy
2
Department of Physics and Astronomy, UCLA,
430 Portola Plaza,
Box 951547,
Los Angeles,
CA
90095-1547,
USA
3
Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna,
Via Gobetti 93/2,
40129
Bologna,
Italy
★★ Corresponding author; cristiano.fanelli@inaf.it
Received:
7
June
2024
Accepted:
21
August
2024
We present a high-resolution chemical study of a representative sample of 21 luminous giant stars in Liller 1, a complex stellar system in the Galactic bulge, based on H-band spectra acquired with the Near-Infrared Spectrograph at KeckII. In this sample, we found fifteen stars with a subsolar iron abundance and enhanced [α/Fe] and [Al/Fe], likely older, having formed early and quickly from gas mainly enriched by type II supernovae, and six stars with supersolar iron and roughly solar-scaled [α/Fe] and [Al/Fe], likely younger, having formed at later epochs from gas also enriched by type Ia supernovae. Moreover, both subpopulations show enhanced [N/Fe], as in the bulge field, approximately solar-scaled [V/Fe], and depletion of [C/Fe] and 12C/13C with respect to the solar values, indicating the occurrence of significant mixing in the stellar interiors of these evolved stars. Our study also reveals that the subsolar subpopulation shows some structuring, and the presence of a third subcomponent with iron content and intermediate [α/Fe] enhancement, in between that of the metal-poor and metal-rich main subpopulations, has been statistically assessed, providing the chemical signature of both an extended star formation with multiple bursts and some self-enrichment.
Key words: techniques: spectroscopic / stars: abundances / stars: late-type / Galaxy: bulge / Galaxy: stellar content / infrared: stars
Based on observations collected at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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