J/A+A/300/751 Metal-poor stars spectroscopy. II (Axer+, 1995)
Spectroscopic analyses of metal-poor stars. II. The evolutionary stage of
subdwarfs.
AXER M., FUHRMANN K., GEHREN T.
<Astron. Astrophys. 300, 751 (1995)>
=1995A&A...300..751A 1995A&A...300..751A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, metal-deficient; Stars, masses; Stars, distances
Keywords: stars: distances - stars: evolution - stars: fundamental parameters -
stars: kinematics - stars: subdwarfs
Description:
Models of post-main sequence stellar evolution of VandenBerg & Bell
have been applied to determine spectroscopic masses and distances for
metal-poor stars. Careful consideration of the most important error
sources published in more recent papers such as VandenBerg for
the first time allow us to draw firm statistical conclusions.
It is shown that the evolutionary calculations qualitatively fit to
the observed stellar parameters whereas quantitatively they predict
too high ages for metal-poor stars. As an important result we confirm
that evolutionary sequences need to be calibrated with respect to their
metal abundance in order to use their absolute predictions of temperature
and luminosity.
In our spectroscopic analyses the strong dependence between surface gravity
and abundances determined from Fe I lines restricts the accuracy of Fe
abundances in subgiants to 0.1 dex at best. The most remarkable result of
our evolutionary and kinematic investigations of halo stars refers to the
large fraction of slightly evolved subgiants among the so-called subdwarfs.
Since conventional photometric approaches often assume that the great
majority of metal-poor stars are dwarfs this results in distances that
are systematically too low for their samples.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 87 115 Fundamental stellar parameters of the
program stars
table3 124 115 Stellar parameters derived from spectroscopy
assuming LTE
table4 114 115 Stellar parameters derived from spectroscopy
including non-LTE corrections
table5 101 115 Galactic velocities
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 10 A10 --- HD HD number
12- 20 A9 --- G Giclas number
22- 32 A11 --- Name Other name
34- 37 I4 K Teff Effective temperature for LTE assumption
39- 42 F4.2 [cm/s2] logg1 Surface gravity for LTE assumption
46- 50 F5.2 [Sun] [Fe/H]1 Metallicity for LTE assumption
53- 55 A3 --- Class Subdivision in three classes of LTE assumption
58- 61 F4.2 [cm/s2] Dlogg Non-LTE correction in logg
63- 66 F4.2 [Sun] D[Fe/H] non-LTE correction in [Fe/H]
68- 71 F4.2 [cm/s2] logg2 Surface gravity for non-LTE assumption
73- 76 F4.2 [cm/s2] e_logg1 rms uncertainty on log g1 (LTE value)
78- 82 F5.2 [Sun] [Fe/H]2 Metallicity for non-LTE assumption
84- 87 F4.2 [Sun] e_[Fe/H]1 rms uncertainty on [Fe/H]1 (LTE value)
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Byte-by-byte Description of file: table3, table4
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Bytes Format Units Label Explanations
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1- 10 A10 --- HD Hd number
13- 20 A8 --- G Giclas number
22- 32 A11 --- Name Other name
36- 42 F7.4 [K] D(log(Teff)) Temperature corrections necessary for
individual adjustment to the metal abundance
44- 48 F5.2 mag BC Bolometric correction
52- 55 F4.2 solMass Mass Mass
58- 61 F4.2 solMass e_Mass rms uncertainty on Mass
63- 68 F6.4 arcsec plx Spectroscopic parallax
70- 75 F6.4 arcsec e_plx rms uncertainty on plx
77- 79 I3 pc Dist Distance
82- 84 I3 pc e_Dist rms uncertainty on distance
86- 90 F5.2 mag MV Absolute visual magnitude
92- 95 F4.2 mag e_MV rms uncertainty on MV
97-101 F5.2 mag Mbol Bolometric magnitude
103-106 F4.2 mag e_Mbol rms uncertainty on Mbol
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Byte-by-byte Description of file: table5
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Bytes Format Units Label Explanations
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1- 10 A10 --- HD HD number
13- 20 A8 --- G Giclas number
22- 32 A11 --- Name Other name
34- 37 I4 km/s RV Radial velocity
39- 44 F6.4 s/yr pmRA proper motion in right ascension
46- 51 F6.3 arcsec/yr pmDE Proper motion in declination
53- 56 I4 km/s U1 U velocity for LTE assumption
58- 61 I4 km/s V1 V velocity for LTE assumption
63- 66 I4 km/s W1 W velocity for LTE assumption
68- 71 I4 km/s Vgal1 Galactic velocity for LTE assumption
74- 76 I3 km/s e_Vgal1 rms uncertainty on Vgal1
78- 81 I4 km/s U2 U velocity for non-LTE assumption
83- 86 I4 km/s V2 V velocity for non-LTE assumption
88- 91 I4 km/s W2 W velocity for non-LTE assumption
93- 96 I4 km/s Vgal2 Galactic velocity for non-LTE assumption
99-101 I3 km/s e_Vgal2 rms uncertainty on Vgal2
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(End) Patricia Bauer [CDS] 05-Jan-1995