J/A+A/377/911 Age-metallicity relation in solar neighbourhood (Feltzing+, 2001)
The solar neighbourhood age-metallicity relation. Does it exist?
Feltzing S., Holmberg J., Hurley J.R.
<Astron. Astrophys. 377, 911 (2001)>
=2001A&A...377..911F 2001A&A...377..911F
ADC_Keywords: Stars, dwarfs ; Stars, late-type ; Abundances ; Stars, ages ;
Stars, masses; Effective temperatures
Keywords: stars: fundamental parameters - stars: late-type -
solar neighbourhood - galaxy: stellar content
Abstract:
We derive stellar ages, from evolutionary tracks, and metallicities,
from Stroemgren photometry, for a sample of 5828 dwarf and sub-dwarf
stars from the Hipparcos (Cat. I/239) Catalogue. This stellar disk
sample is used to investigate the age-metallicity diagram in the solar
neighbourhood. Such diagrams are often used to derive a so called
age-metallicity relation. Because of the size of our sample, we are
able to quantify the impact on such diagrams, and derived relations,
due to different selection effects. Some of these effects are of a
more subtle sort, giving rise to erroneous conclusions. In particular
we show that [1] the age-metallicity diagram is well populated at all
ages and especially that old, metal-rich stars do exist, [2] the
scatter in metallicity at any given age is larger than the
observational errors, [3] the exclusion of cooler dwarf stars from an
age-metallicity sample preferentially excludes old, metal-rich stars,
depleting the upper right-hand corner of the age-metallicity diagram,
[4] the distance dependence found in the Edvardsson et al. (1993, Cat.
J/A+A/275/101) sample by Garnett & Kobulnicky (2000ApJ...532.1192G 2000ApJ...532.1192G)
is an expected artifact due to the construction of the original
sample. We conclude that, although some of it can be attributed to
stellar migration in the galactic disk, a large part of the observed
scatter is intrinsic to the formation processes of stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 48 5828 Stellar parameters derived in this work
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
J/A+A/275/101 : Chemical evolution of the galactic disk I. (Edvardsson+ 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP Hipparcos (Cat. I/239) number
8- 12 F5.2 mag VMAG Absolute V magnitude
14- 18 F5.2 [K] log(Teff) Effective temperature
20- 24 F5.2 [Sun] [Me/H] Metallicity derived from the Stroemgren
photometry
26- 31 F6.3 Gyr Age Mean age
33- 38 F6.3 Gyr e_Age rms uncertainty on Age
40- 41 I2 --- Nfit Number of good fits
43- 48 F6.3 solMass Mass Stellar mass
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Acknowledgements: Sofia Feltzing
(End) Patricia Bauer [CDS] 04-Oct-2001