J/A+A/654/A170 Abundances of metal-poor stars (Matas Pinto+, 2021)
The metal-poor end of the Spite plateau: II. Detailed chemical investigation.
Matas Pinto A.M., Spite M., Caffau E., Bonifacio P., Sbordone L.,
Sivarani T., Steffen M., Spite F., Francois P., Di Matteo P.
<Astron. Astrophys. 654, A170 (2021)>
=2021A&A...654A.170M 2021A&A...654A.170M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, population II ; Abundances ; Equivalent widths
Keywords: stars: abundances - stars: Population II - line: formation -
line: profiles - Galaxy: abundances - Galaxy: evolution
Abstract:
The study of old, metal-poor stars deepens our knowledge on the early
stages of the universe. In particular, the study of these stars gives
us a valuable insight into the masses of the first massive stars and
their emission of ionising photons.
We present a detailed chemical analysis and determination of the
kinematic and orbital properties of a sample of 11 dwarf stars. These
are metal-poor stars, and a few of them present a low lithium content.
We inspected whether the other elements also present anomalies.
We analysed the high-resolution UVES spectra of a few metal-poor stars
using the Turbospectrum code to synthesise spectral lines profiles.
This allowed us to derive a detailed chemical analysis of Fe, C, Li,
Na, Mg, Al, Si, CaI, CaII, ScII, TiII, Cr, Mn, Co, Ni, Sr, and Ba.
We find excellent coherence with the reference metal-poor First Stars
sample. The lithium-poor stars do not present any anomaly of the
abundance of the elements other than lithium. Among the Li-poor stars,
we show that CS 22882-027 is very probably a blue-straggler. The star
CS 30302-145, which has a Li abundance compatible with the plateau,
has a very low Si abundance and a high Mn abundance. In many aspects,
it is similar to the α-poor star HE 1424-0241, but it is less
extreme. It could have been formed in a satellite galaxy and later
been accreted by our Galaxy. This hypothesis is also supported by its
kinematics.
Description:
The observations of the stars we studied are described in detail in
Paper I (Sbordone et al., 2010A&A...522A..26S 2010A&A...522A..26S, Cat. J/A+A/522/A26)
(see their Table 1).
Briefly, observations were performed with the high-resolution
spectrograph UVES at the ESO-VLT. The spectra have a resolving power
R≃40000 and were centred at 390nm (spectral range: 330-451nm) and
580nm (spectral range: 479-680nm). For two stars (BS 17572-100 and HE
1413-1954) that were previously studied in the frame of the HERES
program (Christlieb et al., 2004A&A...428.1027C 2004A&A...428.1027C; Barklem et al.,
2005A&A...439..129B 2005A&A...439..129B, Cat. J/A+A/439/129) from UVES spectra centred at
437nm (spectral range: 376-497nm), the blue spectra were centred at
346 nm (spectral range: 320-386nm). The S/N of the spectra at 400nm
is only about half of the S/N measured at 670nm (see Table 1 in Paper I)
and thus generally does not exceed 50. For two stars, CS 22188-033 and
HE 0148-2611, new UVES spectra from the ESO archives, centred at 390
and 580nm, were also used, increasing the S/N ratio of the mean
spectrum. The data were reduced using the standard UVES pipeline with
the same procedures as used in Bonifacio et al. (2007A&A...462..851B 2007A&A...462..851B).
Here we present the table with equivalent widths discussed in the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 52 11 List of studied stars
table.dat 70 1268 Abundances
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See also:
J/A+A/522/A26 : Fe Abundances in metal-poor stars (Sbordone+ 2010)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star identifier
13- 14 I2 h RAh Simbad Right ascension (J2000)
16- 17 I2 min RAm Simbad Right ascension (J2000)
19- 23 F5.2 s RAs Simbad Right ascension (J2000)
25 A1 --- DE- Declination sign (J2000.0)
26- 27 I2 deg DEd Declination (J2000.0)
29- 30 I2 arcmin DEm Declination (J2000.0)
32- 35 F4.1 arcsec DEs Declination (J2000.0)
37- 52 A16 --- SName Simbad name
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star identifier
16- 23 F8.3 0.1nm lambda Wavelength λ, in Å
27- 31 A5 --- Ion Species identifier
38- 41 F4.2 eV EP Excitation Potential
45- 50 F6.3 [-] loggf Log of the oscillator strength
54- 60 F7.3 10-13m EW ? Equivalent width, in mÅ
61- 63 A3 --- n_EW [syn ] syn for spectrum synthesis
65- 70 F6.3 --- Abund Abundance
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Acknowledgements:
Aroa del Mar Matas, Aroa.del-Mar-Matas-Pinto(at)obspm.fr
References:
Sbordone et al., Paper I 2010A&A...522A..26S 2010A&A...522A..26S, Cat. J/A+A/522/A26
(End) Patricia Vannier [CDS] 25-Aug-2021