| Issue |
A&A
Volume 684, April 2024
|
|
|---|---|---|
| Article Number | L4 | |
| Number of page(s) | 8 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202449485 | |
| Published online | 08 April 2024 | |
Letter to the Editor
High speed stars
III. Detailed abundances and binary nature of the extreme speed star GHS143⋆,⋆⋆
1
GEPI, Observatoire de Paris, Université PSL, CNRS, 5 Place Jules Janssen, 92190 Meudon, France
e-mail: elisabetta.caffau@obspm.fr
2
Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Ciencias Físicas – Instituto de Astrofísica, Autopista Concepción-Talcahuano, 7100 Talcahuano, Chile
3
European Southern Observatory, Casilla, 19001 Santiago, Chile
4
GEPI, Observatoire de Paris, Université PSL, CNRS, 77 Av. Dendert-Rocheau, 75014 Paris, France
5
UPJV, Université de Picardie Jules Verne, 33 Rue St Leu, 80080 Amiens, France
6
Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Ciencias Físicas – Instituto de Astrofísica, Fernandez Concha 700, Las Condes, Santiago, Chile
7
Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, Laboratoire Lagrange, BP 4229, 06304 Nice, France
8
Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
Received:
4
February
2024
Accepted:
8
March
2024
Context. The Gaia satellite has provided the community with three releases containing astrometrical and photometric data as well as by products, such as stellar parameters and variability indicators.
Aims. By selecting in the Gaia database, one can select stars with the requested characteristics, such as high speed. At present any selection is based on available Gaia releases including a subset of the observations. This, for some stars, can show some limitations, for example there is still not a sufficient number of observations to detect binarity.
Methods. We investigated a star selected in Gaia EDR3 for its high speed that appears unbound to the Galaxy. We requested high-quality spectra to derive more information on the star.
Results. From the spectroscopic investigation we confirm the low metallicity content of the star, and we derive a detailed chemical composition. The star is poor in carbon and very rich in oxygen: [(C+N+O)/Fe] = +0.65. From the two spectra observed we conclude that the star is in a binary system and from the investigation of the ionisation balance we derive that the star is closer than implied by the Gaia DR3 parallax, and thus has a a lower intrinsic luminosity.
Conclusions. The star is probably still unbound, but there is the possibility that it is bound to the Galaxy. Its low carbon abundance suggests that the star was formed in a dwarf galaxy.
Key words: stars: abundances / Galaxy: abundances / Galaxy: evolution / Galaxy: formation
A table of the lines investigated is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/684/L4
© 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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