J/A+A/684/L4 High speed stars. III. Line list (Caffau+, 2024)
High speed stars:
III. Detailed abundances and binary nature of the extreme speed star GHS143.
Caffau E., Bonifacio P., Monaco L., Sbordone L., Spite M., Francois P.,
Panuzzo P., Sartoretti P., Chemin L., Thevenin F., Mucciarelli A.
<Astron. Astrophys. 684, L4 (2024)>
=2024A&A...684L...4C 2024A&A...684L...4C (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: stars: abundances - Galaxy: abundances - Galaxy: evolution -
Galaxy: formation
Abstract:
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.
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.
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.
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.
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.
Description:
List of investigated lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
linelist.dat 32 901 Line list
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See also:
J/A+A/638/A122 : High-speed stars. Galactic hitchhikers (Caffau+, 2020)
J/A+A/684/A91 : High-speed stars. II. (Bonifacio+, 2024)
Byte-by-byte Description of file: linelist.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- El Chemical element with ionisation state
7- 14 F8.4 nm lambda laboratory wavelength
16- 21 F6.3 [-] loggf logarithm of the oscillator strength
23- 32 F10.3 cm-1 ELow Energy of the lower level of the transition
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Acknowledgements:
Elisabetta Caffau, Elisabetta.Caffau(at)obspm.fr
References:
Caffau et al., Paper I 2020A&A...638A.122C 2020A&A...638A.122C, Cat. J/A+A/638/A122
Caffau et al., Paper II 2024A&A...684A..91C 2024A&A...684A..91C, Cat. J/A+A/684/A91
(End) Patricia Vannier [CDS] 20-Mar-2024