J/A+A/425/671 Equivalent widths of 10 metal-poor halo stars (Bai+, 2004)
Chemical abundances of 10 metal-poor halo stars.
Bai G.S., Zhao G., Chen Y.Q., Shi J.R., Klochkova V.G., Panchuk V.E.,
Qiu H.M., Zhang H.W.
<Astron. Astrophys. 425, 671 (2004)>
=2004A&A...425..671B 2004A&A...425..671B
ADC_Keywords: Stars, population II ; Stars, metal-deficient ; Equivalent widths
Keywords: stars: abundances - stars: fundamental parameters -
Galaxy: abundances - Galaxy: halo
Abstract:
We presented the observed information of ten metal-poor halo stars
with the metallicity range -2.3<[Fe/H]< -1.4 and derived their
stellar parameters, acquired some elemental abundances relative to
iron and discussed the relation between the abundance ratio and the
metallicity. The stars were observed using the 6m telescope of the
Special Astrophysical Observatory with the ECHELLE spectrometer PFES
equipped with the CCD (1040x1160 pixels, pixel size 16x16µm). The
spectral wavelength coverage is of 430-798nm with the resolving power
of 15000 and the signal-to-noise ratio is about 200.
It was found that oxygen abundances are nearly constant at a level of
0.6dex for our metal-poor halo stars when the non-LTE correction is
considered. The alpha-elements (Mg, Si, Ca and Ti) are overabundant
relative to Fe and decrease with increasing metallicity. We also
obtained a significant underabundant non-LTE [Na/Fe] ratio from NaI D
lines which have large deviation from LTE assumption. Scandium is
marginally overabundant with respect to iron and tends to decrease
with increasing metallicity like the alpha-elements. Nearly solar
value of [Cr/Fe] ratio and underabundant [Mn/Fe] ratio are obtained.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 64 10 Star positions and magnitudes (from Simbad)
ewline.dat 111 197 Atomic line data and equivalent widths
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See also:
J/A+AS/141/491 : Chemical composition of halo and disk stars (Nissen+, 2000)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
15- 16 I2 h RAh Right ascension (J2000.0)
18- 19 I2 min RAm Right ascension (J2000.0)
21- 24 F4.1 s RAs Right ascension (J2000.0)
26 A1 --- DE- Declination sign (J2000.0)
27- 28 I2 deg DEd Declination (J2000.0)
30- 31 I2 arcmin DEm Declination (J2000.0)
33- 34 I2 arcsec DEs Declination (J2000.0)
38- 42 F5.2 mag Bmag ? B magnitude
44- 48 F5.2 mag Vmag ? V magnitude
50- 53 A4 --- SpType Spectral type
55- 64 A10 "Y-M-D" ObsDate Observation Date
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Byte-by-byte Description of file: ewline.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm Lambda Wavelength
11- 14 A4 --- Ion Specie name and ionization
16- 19 F4.2 eV EP Excitation potential
22- 26 F5.2 --- loggf log of Oscillator Strength
29- 31 F3.1 --- f6 Enhancement factor
34- 39 F6.1 0.1pm EW1 ? Equivalent width for HD 108177
42- 47 F6.1 0.1pm EW2 ? Equivalent width for HD 149414
50- 55 F6.1 0.1pm EW3 ? Equivalent width for BD+02 3375
58- 63 F6.1 0.1pm EW4 ? Equivalent width for BD+20 3603
66- 71 F6.1 0.1pm EW5 ? Equivalent width for BD+26 2606
74- 79 F6.1 0.1pm EW6 ? Equivalent width for BD+28 2137
82- 87 F6.1 0.1pm EW7 ? Equivalent width for BD+29 2091
90- 95 F6.1 0.1pm EW8 ? Equivalent width for BD+34 2476
98-103 F6.1 0.1pm EW9 ? Equivalent width for BD+42 2667
106-111 F6.1 0.1pm EW10 ? Equivalent width for BD+51 1696
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Acknowledgements: Chen Yu Qin, cyq(at)ns.bao.ac.cn
(End) Patricia Vannier [CDS] 17-Sep-2004