J/A+A/562/A146 Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)
Chemical compositions of six metal-poor stars in the ultra-faint dwarf
spheroidal galaxy Bootes I.
Ishigaki M.N., Aoki W., Arimoto N., Okamoto S.
<Astron. Astrophys. 562, A146 (2014)>
=2014A&A...562A.146I 2014A&A...562A.146I
ADC_Keywords: Stars, giant ; Equivalent widths ; Abundances
Keywords: nuclear reactions, nucleosynthesis, abundances -
galaxies: abundances - galaxies: dwarf -
galaxies: individual: Bootes I - stars: abundances
Abstract:
We determine chemical compositions of six red giant stars in the
Bootes I dwarf spheroidal galaxy, based on the high-resolution spectra
obtained with the High Dispersion Spectrograph mounted on the Subaru
Telescope. Abundances of 12 elements, including C, Na, alpha, Fe-peak,
and neutron capture elements, were determined for the sample stars.
The abundance results were compared to those in field Milky Way halo
stars previously obtained using an abundance analysis technique
similar to the present study. We confirm the low metallicity of
Boo-094 ([Fe/H]=-3.4). Except for this star, the abundance ratios
([X/Fe]) of elements lighter than zinc are generally homogeneous with
small scatter around the mean values in the metallicities spanned by
the other five stars (-2.7<[Fe/H]←1.8). Specifically, all of the
sample stars with [Fe/H]>-2.7 show no significant enhancement of
carbon. The [Mg/Fe] and [Ca/Fe] ratios are almost constant with a
modest decreasing trend with increasing [Fe/H] and are slightly lower
than the field halo stars. The [Sr/Fe] and [Sr/Ba] ratios also tend to
be lower in the Bootes I stars than in the halo stars. Our results of
small scatter in the [X/Fe] ratios for elements lighter than zinc
suggest that these abundances were homogeneous among the ejecta of
prior generation(s) of stars in this galaxy.
Description:
Equivalent widths and chemical abundances of the six giant stars in
Bootes I dwarf spheroidal galaxy (Boo-009, Boo-094, Boo-117, Boo-121,
Boo-127, Boo-911) and the two Milky Way halo stars (HD216143, HD85773)
are presented. For each spectral line, excitation potential, loggf
values, measured equivalent widths and abundances are given.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 63 8 List of studied stars
table4.dat 45 619 Equivalent widths and abundances
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Name, as in table4.dat
11- 12 I2 h RAh Simbad Hour of Right Ascension (J2000.0)
14- 15 I2 min RAm Simbad Minute of Right Ascension (J2000.0)
17- 21 F5.2 s RAs Simbad Second of Right Ascension (J2000.0)
23 A1 --- DE- Simbad Sign of the Declination (J2000.0)
24- 25 I2 deg DEd Simbad Degree of Declination (J2000.0)
27- 28 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0)
30- 33 F4.1 arcsec DEs Simbad Arcsecond of Declination (J2000.0)
35- 39 F5.2 mag Bmag ? Simbad B band magnitude
41- 44 F4.2 mag Vmag ? Simbad V band magnitude
46- 63 A18 --- SName Simbad name
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Object name
10- 11 I2 --- Z [11/56] Atomic number
13 I1 --- Ion State of ionization (1=neutral)
16- 22 F7.2 0.1nm lambda Wavelength of line (Å)
24- 27 F4.2 eV chi.ex Excitation potential χ
29- 33 F5.2 [-] loggf Oscillator strength
35- 39 F5.1 0.1pm EW Equivalent width (mÅ)
41- 45 F5.2 [-] Abund Absolute abundance (log scale, A(H)=12)
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Acknowledgements:
Miho N. Ishigaki, miho.ishigaki(at)ipmu.jp
(End) Miho N. Ishigaki [IPMU], Patricia Vannier [CDS] 06-Jan-2014