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J/A+A/314/191     Atmospheric parameters in metal-poor stars. I (Gratton+, 1996)

Abundances of light elements in metal-poor stars. I. Atmospheric parameters and a new Teff scale. Gratton R.G., Carretta E., Castelli F. <Astron. Astrophys. 314, 191 (1996)> =1996A&A...314..191G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, metal-deficient ; Abundances Keywords: stars: fundamental parameters - stars: atmospheres - stars: abundances - stars: population II Abstract: We present atmospheric parameters for about 300 stars of different chemical composition, whose spectra will be used to study the galactic enrichment of Fe and light elements. These parameters were derived using an homogeneous iterative procedure, which considers new calibrations of colour-Teff relations for F, G and K-type stars based on Infrared Flux Method (IRFM) and interferometric diameters for population I stars, and the Kurucz (1992) model atmospheres. We found that these calibrations yield a self-consistent set of atmospheric parameters for Teff>4400K, representing a clear improvement over results obtained with older model atmospheres. Using this Teff -scale and Fe equilibrium of ionization, we obtained very low gravities (implying luminosities incompatible with that expected for RGB stars) for metal-poor stars cooler than 4400K; this might be due either to a moderate Fe overionization (expected from statistical equilibrium calculations) or to inadequacy of Kurucz models to describe the atmospheres of very cool giants. Our Teff scale is compared with other scales recently used for metal-poor stars; it agrees well with those obtained using Kurucz (1992) models, but it gives much larger Teff's than those obtained using OSMARCS models (Edvardsson et al. 1993). This difference is attributed to the different treatment of convection in the two sets of models. For the Sun, the Kurucz (1992) model appears to be preferable to the OSMARCS ones because it better predicts the solar limb darkening; furthermore, we find that our photometric Teff 's for metal-poor stars agree well with both direct estimates based on the IRFM, and with Teff's derived from Hα wings when using Kurucz models. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tables 68 287 Tables 2,3,4,5 and 6 of the paper
See also: J/A+A/350/955 : Atmospheric parameters in metal-poor stars. II (Gratton+, 1999) Byte-by-byte Description of file: tables
Bytes Format Units Label Explanations
2 I1 --- Table [2/6] Number of the table (1) 4- 13 A10 --- Star Designation 15- 16 I2 h RAh ? Right Ascension J2000 (hours) (2) 18- 19 I2 min RAm ? Right Ascension J2000 (minutes) (2) 21- 24 F4.1 s RAs ? Right Ascension J2000 (seconds) (2) 26 A1 --- DE- Declination J2000 (sign) (2) 27- 28 I2 deg DEd ? Declination J2000 (degrees) (2) 30- 31 I2 arcmin DEm ? Declination J2000 (minutes) (2) 33- 34 I2 arcsec DEs ? Declination J2000 (seconds) (2) 38- 41 I4 K Teff Effective Temperature 43- 47 F5.2 [cm/s2] logg Suface gravity 50- 54 F5.2 [Sun] [A/H] Abundance [A/H] (logarithmic scale) 57- 60 F4.2 km/s Vel Microturbulent velocities 63- 68 F6.3 --- Slope ? Slope of relation between abundances and excitation potential (Only in table2)
Note (1): The table number specifies the sample: 2 = Atmospheric parameters for stars of original sample 3 = Atmospheric parameters for stars of TLLS sample (Tomkin et al., 1992AJ....104.1568T) 4 = Atmospheric parameters for stars of SKPL sample (Sneden et al., 1991AJ....102.2001S) 5 = Atmospheric parameters for stars of E93 sample (Edvardsson et al., 1993A&A...275..101E) 6 = Atmospheric parameters for stars of ZM90 sample (Zhao & Magain, 1990A&A...238..242Z) Note (2): the positions of the stars have been added at CDS, using the SIMBAD data-base. There is one star ("anon" in Table 4) for which no position could be found.
Acknowledgement: R.G. Gratton
(End) Patricia Bauer, Francois Ochsenbein [CDS] 24-Oct-1996
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