J/ApJ/527/879 Gravities for late-type stars (Allende Prieto+, 1999)
A consistency test of spectroscopic gravities for late-type stars
Allende Prieto C., Garcia Lopez R.J., Lambert D.L., Gustafsson B.
<Astrophys. J. 527, 879 (1999)>
=1999ApJ...527..879A 1999ApJ...527..879A
ADC_Keywords: Abundances, [Fe/H] ; Models, atmosphere ; Stars, late-type ;
Parallaxes, trigonometric ; Stars, late-type
Keywords: stars: abundances - stars: atmospheres - stars:
fundamental parameters - stars: late-type
Abstract:
Chemical analyses of late-type stars are usually carried out following
the classical recipe: LTE line formation and homogeneous,
plane-parallel, flux-constant, and LTE model atmospheres. We review
different results in the literature that have suggested significant
inconsistencies in the spectroscopic analyses, pointing out the
difficulties in deriving independent estimates of the stellar
fundamental parameters and hence, detecting systematic errors. The
trigonometric parallaxes measured by the Hipparcos mission provide
accurate appraisals of the stellar surface gravity for nearby stars,
which are used here to check the gravities obtained from the
photospheric iron ionization balance. We find an approximate agreement
for stars in the metallicity range -1.0≲[Fe/H]≲0, but the
comparison shows that the differences between the spectroscopic and
trigonometric gravities decrease toward lower metallicities for more
metal-deficient dwarfs (-2.5≲[Fe/H]≲-1.0), which casts a shadow
upon the abundance analyses for extreme metal-poor stars that make use
of the ionization equilibrium to constrain the gravity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 243 Data for the Stars in the Comparison
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star Name
15- 19 F5.2 [Sun] [Fe/H] Log Iron to Hydrogen abundance ratio
23- 27 F5.2 solMass Mass Mass of the star in solar masses
31- 35 F5.2 mag Vmag V band magnitude
39- 43 F5.2 mag VMag Absolute V band magnitude
48- 51 I4 K Teff Effective temperature
54- 58 F5.2 [cm/s2] HLogG Log surface gravity from HIPPARCOS
62- 66 F5.2 [cm/s2] SLogG Log surface gravity from spectroscopic
measurements
70- 75 F6.2 mas Plx Parallax of the star
78- 81 F4.2 mas e_Plx Error in Para
84 A1 --- r_Name Reference code number (1)
86 A1 --- f_Name Isochrone reference code number (2)
89-104 A16 --- CCDM Components name of double and multiple
stars from Dommanget & Nys Cat. I/211
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Note (1):
0 = Gratton et al. (1997A&A...314..191G 1997A&A...314..191G)
1 = Edvardsson (1998A&A...190..148E 1998A&A...190..148E)
2 = Bonnell & Bell (1993MNRAS.264..334B 1993MNRAS.264..334B)
3 = Fuhrmann et al. (1997A&A...323..909F 1997A&A...323..909F)
4 = Magain (1989A&A...305..245M 1989A&A...305..245M)
5 = Ryan, Norris & Beers (1996ApJ...471..254R 1996ApJ...471..254R)
Note (2):
0 = within the metallicity range of
Bergbusch & Vandenberg (1992ApJS...81..163B 1992ApJS...81..163B)
1 = [Fe/H] too low ([Fe/H] = -2.26 is assumed in the grid of
Bergbusch & Vandenberg (1992) or [Fe/H] too high ([Fe/H] = -0.47
is used)
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History:
From ApJ electronic edition
(End) Greg Schwarz [AAS] 17-Mar-2000