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J/A+A/350/955    Atmospheric parameters in metal-poor stars. II (Gratton+, 1999)

Abundances of light elements in metal-poor stars. II. Non-LTE abundance corrections Gratton R.G., Carretta E., Eriksson K., Gustafsson B. <Astron. Astrophys. 350, 955 (1999)> =1999A&A...350..955G
ADC_Keywords: Stars, metal-deficient ; Abundances ; Models, atmosphere Keywords: stars: abundances - stars: atmospheres - stars: population II - Sun: abundances Abstract: We present non-LTE corrections to abundances of Fe, O, Na, and Mg derived from LTE analyses of F-K stars over a broad range of gravities and metal abundances; they were obtained using statistical equilibrium calculations and new model atoms. Line opacity was considered by means of an empirical procedure where it was attributed to a veil of weak Fe I lines; in the case of solar-type dwarfs, results were compared with those obtained using (LTE) mean intensities computed from OSMARCS models. We think that the empirical procedure produces better results for metal-poor stars, while mean intensities should perhaps be preferred for the Sun (where departures from LTE are anyway not very large). Collisions with both electrons and H I atoms were considered. Since cross sections for this second mechanism are very poorly known, we calibrated them empirically by matching observations of RR Lyrae variables at minimum light (discussed in Clementini et al., 1995, Cat. J/AJ/110/2319). These stars were selected because non-LTE effects are expected to be larger in these stars than in those usually considered in the study of the chemical evolution of the Galaxy (cool main sequence and red giant branch stars). We found that different non-LTE mechanisms are important for the different species and transitions considered; on the whole, our calculations yielded moderate corrections to LTE abundances for high excitation O lines in warm dwarfs and giants, Na and Mg lines in giants and supergiants, and Fe I lines in F-supergiants (where corrections becomes very large for IR O lines). Non-LTE corrections were found to be negligible in the other cases studied. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file levels.dat 42 138 Levels for Fe I, O I, Na I and Mg I atoms bound.dat 43 160 Bound-bound transitions abundcor.dat 111 520 Corrections to LTE abundances
See also: J/A+A/314/191 : Atmospheric parameters in metal-poor stars. I (Gratton+, 1996) J/AJ/110/2319 : Abundances in RR Lyrae variables (Clementini+ 1995) Byte-by-byte Description of file: levels.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Ion Ion designation 6- 7 I2 --- Level Level 10- 17 F8.1 cm-1 E Energy 21- 22 I2 --- Weight Statistical weight 25- 31 A7 --- Ident Identification 35- 42 E8.2 cm+2 CrossSec ? Threshold Cross Section
Byte-by-byte Description of file: bound.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Ion Ion designation 6- 7 I2 --- UpperL Upper level 10- 11 I2 --- LowerL Lower level 13- 20 F8.1 nm Lambda Wavelength 25- 32 E8.2 --- Abs Absorption oscillator strength 36- 43 E8.2 s-1 Einst Einstein factor
Byte-by-byte Description of file: abundcor.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Ion Ion designation 6- 9 F4.1 [Sun] [A/H] Abundance [A/H] (logarithmic scale) 11- 18 F8.3 0.1nm Lambda Wavelength 20- 23 F4.2 eV EP Excitation Potential 25- 30 F6.1 0.1pm EW Equivalent Width 32- 36 F5.2 --- C4kK1.5 ?=-11 Correction for Teff=4000, logg=1.50 (1) 38- 43 F6.2 --- C4kK3 ?=-11 Correction for Teff=4000, logg=3.00 (1) 45- 50 F6.2 --- C4kK4.5 ?=-11 Correction for Teff=4000, logg=4.50 (1) 52- 57 F6.2 --- C5kK1.5 ?=-11 Correction for Teff=5000, logg=1.50 (1) 59- 63 F5.2 --- C5kK3 ?=-11 Correction for Teff=5000, logg=3.00 (1) 65- 70 F6.2 --- C5kK4.5 ?=-11 Correction for Teff=5000, logg=4.50 (1) 72- 77 F6.2 --- C6kK1.5 ?=-11 Correction for Teff=6000, logg=1.50 (1) 79- 84 F6.2 --- C6kK3 ?=-11 Correction for Teff=6000, logg=3.00 (1) 86- 90 F5.2 --- C6kK4.5 ?=-11 Correction for Teff=6000, logg=4.50 (1) 92- 97 F6.2 --- C7kK1.5 ?=-11 Correction for Teff=7000, logg=1.50 (1) 99-104 F6.2 --- C7kK3 ?=-11 Correction for Teff=7000, logg=3.00 (1) 106-111 F6.2 --- C7kK4.5 ?=-11 Correction for Teff=7000, logg=4.50 (1)
Note (1): correction in the sense [A/H](NLTE) - [A/H](LTE). The value -11 indicates that either the NLTE could not be computed, or gave non-physical results
Acknowledgements: Raffaele Gratton History: * 19-Oct-1999: Original version * 07-Jan-2000: File abundcor.dat was corrected with new tables supplied by the authors. * 25-Mar-2008: Note added about the value -11 in abundcor.dat
(End) Patricia Bauer [CDS] 07-Jan-2000
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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