J/A+A/548/A34 Abundances of carbon-enhanced metal-poor stars (Allen+, 2012)
Elemental abundances and classification of carbon-enhanced metal-poor stars.
Allen D.M., Ryan S.G., Rossi S., Beers T.C., Tsangarides S.A.
<Astron. Astrophys. 548, A34 (2012)>
=2012A&A...548A..34A 2012A&A...548A..34A
ADC_Keywords: Stars, carbon ; Stars, metal-deficient ; Abundances
Keywords: stars: abundances - stars: atmospheres - stars: chemically peculiar -
stars: carbon
Abstract:
We present a detailed study of Carbon-Enhanced Metal-Poor (CEMP)
stars, based on high-resolution spectroscopic observations of a sample
of 18 stars. The stellar spectra for this sample were obtained at the
4.2m William Herschel Telescope (WHT) in 2001 and 2002, using the
Utrecht Echelle Spectrograph (UES), at a resolving power R∼52000 and
S/N∼40, covering the wavelength range λ-λ3700-5700Å.
The atmospheric parameters determined for this sample indicate
temperatures ranging from 4750K to 7100K, log g from 1.5 to 4.3, and
metallicities -3.0≤[Fe/H]≤-1.7. Elemental abundances for C, Na, Mg,
Sc, Ti, Cr, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, Gd, Dy are
determined. Abundances for an additional 109 stars were taken from the
literature and combined with the data of our sample. The literature
sample reveals a lack of reliable abundance estimates for species that
might be associated with the r-process elements for about 67% of CEMP
stars, preventing a complete understanding of this class of stars,
since [Ba/Eu] ratios are used to classify them. Although eight stars
in our observed sample are also found in the literature sample, Eu
abundances or limits are determined for four of these stars for the
first time. From the observed correlations between C, Ba, and Eu, we
argue that the CEMP-r/s class has the same astronomical origin as
CEMP-s stars, highlighting the need for a more complete understanding
of Eu production.
Description:
Abundances for 18 CEMP stars are presented: BS 15621-047,
BS 16033-081, BS 16077-077, BS 16082-129, BS 16543-097, BS 16929-005,
CS 22949-008, CS 29503-010, CS 29512-073, CS 29526-110, CS 29528-028,
CS 31070-073, BS 16080-175, BS 17436-058, CS 22183-015, CS 22887-048,
CS 22898-027, CS 29502-092. Our results were compared to data of 109
stars from the literature.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 148 28 Colours and magnitudes of our program stars
before dereddening
table2.dat 55 2316 Iron lines for DMA subsample
table5.dat 56 5302 All abundances for SAT subsample
table7.dat 76 1128 Other elemental abundances for DMA subsample
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Sample Subsample: DMA (Dinah M. Allen) or
SAT (Stelios A. Tsangarides)
5- 16 A12 --- Star Star name
17 A1 --- n_Star [*] position and magnitude added at CDS
(concerns HD 140283)
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 27 F4.1 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 37 I2 arcsec DEs Declination (J2000)
39- 44 F6.3 mag Vmag ? V magnitude
46- 50 F5.3 mag E(B-V) ? Interstellar reddening
52- 56 F5.3 mag AV ? Absorption in V band
58- 61 F4.3 mag e_AV ? rms uncertainty on AV
63- 67 F5.3 mag B-V ? B-V colour index
68 A1 --- n_B-V [X] X for value not used
70- 74 F5.3 mag V-R ? V-R colour index
76- 80 F5.3 mag V-I ? V-I colour index
82- 87 F6.3 mag Jmag ? J magnitude
89- 92 F4.3 mag e_Jmag ? rms uncertainty on Jmag
94- 99 F6.3 mag Hmag ? H magnitude
101-104 F4.3 mag e_Hmag ? rms uncertainty on Hmag
106-111 F6.3 mag Ksmag ? Ks magnitude
113-116 F4.3 mag e_Ksmag ? rms uncertainty on Ksmag
118-122 F5.1 deg GLON ? Galactic longitude
124-128 F5.1 deg GLAT ? Galactic latitude
130-132 I3 --- S/N ? Signal-to-noise ratio of the high-resolution
spectra around λ4500Å
134-148 A15 --- Note ? Notes
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Byte-by-byte Description of file: table2.dat table5.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Star Star name
14- 18 A5 --- Ion Element code and ionization state
21- 29 F9.4 0.1nm lambda Wavelength of the line
32- 36 F5.3 eV EP Lower excitation potential
39- 44 F6.3 --- loggf Logarithm of oscillator strength
47 I1 --- r_loggf [1/9] References for oscillator strength (1)
49 A1 --- l_EW Upper limit flag on EW
50- 55 F6.2 0.1pm EW ?=- Equivalent width
56 A1 --- n_EW [s] s indicates spectrum synthesis
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Note (1): References as follows:
1 = Fuhr et al. (1988, Cat. VI/72)
2 = Kurucz & Peytremann (1975, SAO Special Report 362
(Cambridge: Smithsonian Institution))
3 = NIST
4 = Ryan & Lambert (1995AJ....109.2068R 1995AJ....109.2068R)
5 = Thevenin (1989A&AS...77..137T 1989A&AS...77..137T)
6 = Kurucz (1989, priv. comm.)
7 = Experimental sources
8 = Fuhr & Wiese (2006, J. Phys. Chem. Ref. D., 35, 4)
9 = Kurucz, R. 1994, CD 22
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Star Star name
15- 19 A5 --- Ion Element code and ionization state
23- 30 A8 0.1nm lambda Wavelength of the line
35- 39 F5.3 eV EP ?=- Lower excitation potential
44- 49 F6.3 --- loggf ?=- Logarithm of oscillator strength
53- 54 I2 --- r_loggf ?=- References for oscillator strength (1)
58- 60 I3 0.1pm EW ?=- Equivalent width for the star
61 A1 --- n_EW [s] s indicates spectrum synthesis
64- 68 F5.2 --- logEps ?=- Average of logε= log(Nx/NH) + 12
72- 76 F5.2 --- [X/Fe] ?=- Average of the overabundance of the
element X relative to Fe
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Note (1): References as follows:
1 = NIST
2 = Fuhrmann et al. (1995A&A...301..492F 1995A&A...301..492F)
3 = Martin et al. (1988, Cat. VI/72)
4 = Bielski (1975, JQSRT, 15, 463)
5 = Biemont & Godefroid (1980, A&A, 84, 361)
6 = Gratton & Sneden (1994, Cat. J/A+A/287/927)
7 = Hannaford et al. (1982ApJ...261..736H 1982ApJ...261..736H)
8 = Hannaford & Lowe (1983, Opt. Eng., 22, 532)
9 = Biemont et al. (1981ApJ...248..867B 1981ApJ...248..867B)
10 = Thevenin (1989A&AS...77..137T 1989A&AS...77..137T)
11 = Sneden et al. (1996ApJ...467..819S 1996ApJ...467..819S)
12 = McWilliam (1998AJ....115.1640M 1998AJ....115.1640M)
13 = Lawler et al. (2001ApJ...556..452L 2001ApJ...556..452L)
14 = Palmeri et al. (2000, Physica Scripta, 61, 323)
15 = Hartog et al. (2003ApJS..148..543D 2003ApJS..148..543D)
16 = Maier & Whaling (1977, JQSRT, 18, 501)
17 = Biemont et al. (1989A&A...222..307B 1989A&A...222..307B)
18 = Lawler et al. (2001ApJ...563.1075L 2001ApJ...563.1075L)
19 = Corliss & Bozman (1962, Experimental Transition Probabilities for
Spectral Lines of Seventy Elements, NBS Monograph 32 (Washington: GPO))
20 = VALD data-base (http://vald.astro.univie.ac.at/~vald/php/vald.php)
21 = Bergstrom et al. (1988, A&A, 192, 337)
22 = average of Kusz (1992A&AS...92..517K 1992A&AS...92..517K) and
Biemont & Lowe (1993A&A...273..665B 1993A&A...273..665B)
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Acknowledgements:
Dinah Moreira Allen, dimallen at astro.iag.usp.br
(End) Patricia Vannier [CDS] 29-Nov-2012