J/A+A/574/A129 The First CEMP star in the Sculptor dSph (Skuladottir+, 2015)
The first carbon-enhanced metal-poor star found in the Sculptor dwarf
spheroidal.
Skuladottir A., Tolstoy E., Salvadori S., Hill V., Pettini M.,
Shetrone M.D., Starkenburg E.
<Astron. Astrophys. 574, A129 (2015)>
=2015A&A...574A.129S 2015A&A...574A.129S
ADC_Keywords: Galaxies, nearby ; Stars, carbon ; Stars, metal-deficient ;
Abundances
Keywords: stars: abundances - galaxies: individual: Sculptor dwarf spheroidal -
galaxies: dwarf - galaxies: evolution
Abstract:
he origin of carbon-enhanced metal-poor (CEMP) stars and their
possible connection with the chemical elements produced by the first
stellar generation is still highly debated. In contrast to the
Galactic halo, not many CEMP stars have been found in the dwarf
spheroidal galaxies around the Milky Way. Here we present detailed
abundances from ESO VLT/UVES high-resolution spectroscopy for ET0097,
the first CEMP star found in the Sculptor dwarf spheroidal, which is
one of the best studied dwarf galaxies in the Local Group. This star
has [Fe/H]=-2.03±0.10, [C/Fe]=0.51±0.10 and [N/Fe]=1.18±0.20,
which is the first nitrogen measurement in this galaxy. The
traditional definition of CEMP stars is [C/Fe]≥0.70, but taking into
account that this luminous red giant branch star has undergone mixing,
it was intrinsically less nitrogen enhanced and more carbon-rich when
it was formed, and so it falls under the definition of CEMP stars, as
proposed by Aoki et al. (2007ApJ...655..492A 2007ApJ...655..492A, Cat. J/ApJ/655/492) to
account for this effect.
Description:
table4.dat includes the linelist used for the abundance determination
of the first carbon-enhanced metal-poor star in Sculptor
table6.dat includes carbon estimates for 85 stars in Sculptor, derived
from CN molecular lines in VLT/FLAMES spectra (wavelength range:
9100-9250Å).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 55 633 Linelist
table6.dat 55 85 Carbon estimates for 85 stars in Sculptor dwarf
spheroidal from CN lines
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See also:
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- El Element species (1)
9- 15 F7.2 0.1nm lambda Wavelength λ (Å)
17- 22 F6.3 eV EP Excitation potential
24- 30 F7.3 [-] loggf Oscillator strength
32 A1 --- l_Abund Limit flag on Abund
33- 37 F5.2 [-] Abund [-1.8/7.5]?=- Abundance logε(Xi) (2)
39- 42 F4.2 [-] e_Abund [0.06/0.8]?=- Measurement error of lines (3)
44- 55 A12 --- Comm Comment if the line is blended
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Note (1): Atomic lines are adopted from the DREAM data base, extracted via VALD.
Note (2): Lines with no associated abundance measurements, are fitted together
with the previous line(s).
Note (3): For elements with less than 5 measured lines.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [ET]
3- 6 I04 --- Star [24/392] Name of star (ETNNNN)
8- 9 I2 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 18 F5.2 s RAs Right ascension (J2000)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000)
24- 25 I2 arcmin DEm Declination (J2000)
27- 30 F4.1 arcsec DEs Declination (J2000)
32- 35 F4.2 [Lsun] logL [2.5/3.3] Luminosity (1)
37- 41 F5.2 [Sun] [Fe/H] [-2.41/-0.9] Metallicity (1)
43 A1 --- l_[C/Fe]e [<] Limit flag on [C/Fe]est
44- 48 F5.2 [Sun] [C/Fe]e [-1.3/-0.3] Estimated [C/Fe] by assuming
[C/N]=-1.2 (2)
50 A1 --- l_[C/Fe]u [<] Limit flag on [C/Fe]upp
51- 55 F5.2 [Sun] [C/Fe]u [-1.3/0.4] Estimated [C/Fe] by assuming
[N/Fe]=0.0 (2)
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Note (1): from Hill et al. (in prep)
Note (2): Simple relation of [O/Fe] with [Fe/H] is assumed, as shown in
Fig. 6a in paper.
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Acknowledgements:
Asa Skuladottir, asa(at)astro.rug.nl
(End) A. Skuladottir [Kapeteyn Astronomical Inst.], P. Vannier [CDS] 12-Nov-2014