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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables 68 287 Tables 2,3,4,5 and 6 of the paper
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See also:
J/A+A/350/955 : Atmospheric parameters in metal-poor stars. II (Gratton+, 1999)
Byte-by-byte Description of file: tables
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Bytes Format Units Label Explanations
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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)
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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 1992AJ....104.1568T)
4 = Atmospheric parameters for stars of SKPL sample
(Sneden et al., 1991AJ....102.2001S 1991AJ....102.2001S)
5 = Atmospheric parameters for stars of E93 sample
(Edvardsson et al., 1993A&A...275..101E 1993A&A...275..101E)
6 = Atmospheric parameters for stars of ZM90 sample
(Zhao & Magain, 1990A&A...238..242Z 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.
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Acknowledgement: R.G. Gratton
(End) Patricia Bauer, Francois Ochsenbein [CDS] 24-Oct-1996