J/A+A/687/A229 Element abundances of 4 metal-poor stars (Mishenina+, 2024)
Peculiarities of the chemical enrichment of metal-poor stars in the Milky Way
galaxy.
Mishenina T., Pignatari M., Usenko I., Soubiran C., Thielemann F.-K.,
Kniazev A.Yu., Korotin S.A., Gorbaneva T.
<Astron. Astrophys. 687, A229 (2024)>
=2024A&A...687A.229M 2024A&A...687A.229M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Stars, metal-deficient ; Equivalent widths ;
Abundances
Keywords: nuclear reactions, nucleosynthesis, abundances - stars: abundances -
stars: Population II - Galaxy: evolution - Galaxy: halo -
Abstract:
The oldest stars in the Milky Way are metal-poor with [Fe/H]←1.0, and
they show peculiar elemental abundances compared to solar. The
relative variations of the chemical compositions between stars is also
increasing with decreasing stellar metallicity, allowing to reveal the
pure signature of unique nucleosynthesis processes. The study of the
r-process is for instance one of the main goals of stellar
archaeology, and metal-poor stars show an unexpected complexity in the
stellar production of the r-process elements in the early Galaxy. In
this work we report the atmospheric parameter, the main dynamic
properties and the abundances of four metal-poor stars: HE 1523-0901,
HD 6268, HD 121135, and HD 195636 (-1.5>[Fe/H]>-3.0). The abundances
are derived from spectra obtained with the HRS echelle spectrograph at
the Southern African Large Telescope, using both LTE and NLTE
approaches, with an average error between 0.10 and 0.20dex. Based on
their kinematical properties, we show that HE 1523-0901 and HD 195636
are halo stars with typical high velocities; HD 121135 has a peculiar
kinematical behaviour making unclear if it is a halo or an accreted
star; and HD 6268 is possibly a rare prototype of very metal-poor
thick disk stars. The abundances derived for our stars are compared
with theoretical stellar models and with other stars with similar
metallicity from the literature.
Description:
Spectral observations were made during 2017-2021 years at the Southern
African Large Telescope (SALT) using the fibre-fed echelle
spectrograph HRS.
Table A1 presents Line list, EWs and abundances of CaI, TiI, TiII,
CrI, FeI, FeII, NiI.
Table B1 presents Line list, and abundances of YII, ZrII, MoI, RuI,
LaII, CeII, PrII, NdII, SmII, GdII, TbII, DyII, HoII, ErII, HfII,
TmII, OsI, IrI
The abundance based on these lines a fit of line profiles was used,
without EW measurements. herefore, EWs are not reported. The star
HD 195636 is not included here, since the lines are weak and distorted
by the high rotation velocity and it was not possible to determine the
abundances of these elements.
Objects:
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RA (2000) DE Designation(s)
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15 26 01.06 -09 11 38.8 HE 1523-0901 = 2MASS J15260106-0911388
01 03 18.17 -27 52 49.9 HD 6268 = 2MASS J01031817-2752499
13 53 33.54 +02 41 41.1 HD 121135 = 2MASS J13533354+0241411
20 32 48.94 -09 21 51.7 HD 195636 = 2MASS J20324895-0921516
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 82 450 Line list, EWs and abundances of CaI, TiI, TiII,
CrI, FeI, FeII and NiI
tableb1.dat 49 239 *Line list, and abundances of
neutron-capture elements
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Note on tableb1.dat: The star HD 195636 is not included here, since the lines
are weak and distorted by the high rotation velocity and it was not possible
to determine the abundances of these elements.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 10 F8.3 0.1nm lambda Wavelength
13- 17 F5.2 --- Species Atomic Number
20- 24 F5.3 eV Elow Lower level potential
26- 31 F6.3 --- loggf Oscillator strength
34- 38 F5.1 0.1pm EW1 ? Equivalent line width for HE 1523-0901
41- 44 F4.2 --- logA1 ? Element abundances for HE 1523-0901 (1)
47- 51 F5.1 0.1pm EW2 ? Equivalent line width for HD 6268
54- 57 F4.2 --- logA2 ? Element abundances for HD 6268 (1)
60- 64 F5.1 0.1pm EW3 ? Equivalent line width for HD 121135
67- 70 F4.2 --- logA3 ? Element abundances for HD 121135 (1)
72- 76 F5.1 0.1pm EW4 ? Equivalent line width for HD 195636
79- 82 F4.2 --- logA4 ? Element abundances for HD 195636 (1)
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Note (1): logA is the element abundances where logA(H)=12.
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 10 F8.3 0.1nm lambda Wavelength
13- 17 F5.2 --- Species Atomic Number
20- 24 F5.3 eV Elow Lower level potential
26- 31 F6.3 --- loggf Oscillator strength
33- 37 F5.2 --- logA1 ? Element abundances for HE 1523-0901 (1)
39- 43 F5.2 --- logA2 ? Element abundances for HD 6268 (1)
45- 49 F5.2 --- logA3 ? Element abundances for HD 121135 (1)
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Note (1): logA is the element abundances where logA(H)=12.
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Acknowledgements:
Tamara Mishenina, tmishenina(at)ukr.net
(End) Tamara Mishenina [AO ONU, Ukraine], Patricia Vannier [CDS] 09-May-2024