J/A+A/624/A44 3D-corrected oxygen abundances for halo stars (Spite+, 2019)
Be and O in the ultra metal-poor dwarf 2MASS J18082002-5104378 and the
Be-O correlation.
Spite M., Bonifacio P., Spite F., Caffau E., Sbordone L., Gallagher A.J.
<Astron. Astrophys. 624, A44 (2019)>
=2019A&A...624A..44S 2019A&A...624A..44S (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, metal-deficient ; Abundances
Keywords: stars: abundances - binaries: spectroscopic - stars: Population II -
stars: individual: 2MASS J18082002-5104378
Abstract:
Measurable amounts of Be could have been synthesised primordially if
the Universe were non-homogeneous or in the presence of late decaying
relic particles.
We investigate the Be abundance in the extremely metal-poor star
2MASS J1808-5104 ([Fe/H]=-3.84) with the aim of constraining
inhomogeneities or the presence of late decaying particles.
High resolution, high signal-to-noise ratio (S/N) UV spectra were
acquired at ESO with the Kueyen 8.2m telescope and the UVES
spectrograph. Abundances were derived using several model atmospheres
and spectral synthesis code.
We measured log(Be/H)=-14.3 from a spectrum synthesis of the region of
the Be line. Using a conservative approach, however we adopted an
upper limit two times higher, i.e. log(Be/H)←14.0. We measured the O
abundance from UV-OH lines and find [O/H]=-3.46 after a 3D
correction.
Our observation reinforces the existing upper limit on primordial Be.
There is no observational indication for a primordial production of
9Be. This places strong constraints on the properties of putative
relic particles. This result also supports the hypothesis of a
homogeneous Universe, at the time of nucleosynthesis. Surprisingly,
our upper limit of the Be abundance is well below the Be measurements
in stars of similar [O/H]. This may be evidence that the Be-O
relation breaks down in the early Galaxy, perhaps due to the escape of
spallation products from the gas clouds in which stars such as 2MASS
J1808-5104 have formed.
Description:
Oxygen abundance with 3D correction of the stars in the sample of
Boesgaard et al. (2011, Cat. J/ApJ/743/140).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
oxy.dat 68 115 *3D-corrected oxygen abundances
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Note on oxy.dat: In this table the parameters of the models and the [O/H]1D
values are those given by Boesgaard et al. (2001ApJ...553..754B 2001ApJ...553..754B), except for
G64-12 for which we give our own measurements.
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See also:
J/ApJ/743/140 : Abundances (Be,α) in metal-poor stars (Boesgaard+, 2011)
Byte-by-byte Description of file: oxy.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Star Name of the star
15- 21 F7.2 K Teff Effective temperature
25- 28 F4.2 [cm/s2] logg logarithm of the gravity in the atmosphere
32- 36 F5.2 --- [M/H] Metallicity
40- 44 F5.2 --- A(Be) log(N(Be)/N(N(H))+12
48- 52 F5.2 --- [O/H]1D 1D value of [O/H]
56- 60 F5.2 --- Cor3D 3D correction
64- 68 F5.2 --- [O/H]3D Abundance [O/H] corrected for 3D effects
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Acknowledgements:
Monique Spite, monique.spite(at)obspm.fr
(End) Patricia Vannier [CDS] 22-Feb-2019