J/A+A/329/943 F & G solar neighbourhood stars new ages (Ng+ 1998)
Revised ages for stars in the solar neighbourhood
Ng Y.K., Bertelli G.
<Astron. Astrophys. 329, 943 (1998)>
=1998A&A...329..943N 1998A&A...329..943N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, ages ; Stars, masses ; Stars, nearby
Keywords: methods: data analysis - stars: general, HR diagram -
Galaxy: solar neighbourhood
Abstract:
New ages are computed for the stars from the Edvardsson et al. (1993,
Cat. J/A+A/275/101) data set. The revised values are systematically
larger toward older ages (t>4Gyr), while they are slightly lower for
t<4Gyr. A similar, but considerably smaller trend is present when the
ages are computed with the distances based on Hipparcos parallaxes.
The resulting age-metallicity relation has a small, but distinct slope
of ∼0.07dex/Gyr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3 40 81 *F & G stars on or near the main sequence data
(no corrections for absolute visual magnitude)
table4 44 108 *F & G stars on or near the sub-giant branch data
(no corrections for absolute visual magnitude)
table5 38 61 *F & G stars on or near the main sequence data
(correction for absolute visual magnitude)
table6 38 128 *F & G stars on or near the sub-giant branch data
(correction for absolute visual magnitude)
table7 38 76 *F & G stars on or near the main sequence data
(as in table3 but with Hipparcos parallax)
table8 38 113 *F & G stars on or near the sub-giant branch data
(as in table4 but with Hipparcos parallax)
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Note to table3 and table4: Data, metallicity and distance from
Edvardsson et al. (1993, Cat. J/A+A/275/101), without any correction
applied to the absolute visual magnitude for the calculation of the
stellar age
Note to table5 and table6: Data, metallicity and distance from
Edvardsson et al. (1993, Cat. J/A+A/275/101), with the Lutz-Kelker
(1973PASP...85..573L 1973PASP...85..573L) correction applied (n=4, sigma_pi/pi=0.15; Hanson
(1979MNRAS.186..875H 1979MNRAS.186..875H) - equation 31) to the absolute visual magnitude for the
calculation of the stellar age
Note ot table7 and table8: Data, metallicity from
Edvardsson et al. (1993, Cat. J/A+A/275/101) and the distance from the
HIPPARCOS parallax, without correction applied to the absolute visual
magnitude for the calculation of the stellar age
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See also:
J/A+A/275/101 : Chemical evolution of the galactic disk I. (Edvardsson+ 1993)
Byte-by-byte Description of file: table*
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Bytes Format Units Label Explanations
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1- 2 A2 --- Cat HR (Cat. V/50) or HD (Cat. III/135)
4- 9 I6 --- No Star ID number
11- 14 F4.2 solMass Mass Average mass in M☉
16- 19 F4.2 solMass e_Mass Estimated uncertainty in the mass
21- 26 F6.3 [Gyr] log(Age) Average age
28- 32 F5.3 [Gyr] e_log(Age) Estimated uncertainty in log(age)
34 I1 --- Fit [0/7] Number of good fits out of the
possible 7 from which the average values
are obtained. See Note (1)
36- 40 F5.2 [Gyr] log(Age)2 ? age obtained from a visual inspection of
an isochrone through each point
(in table4 only)
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Note (1): Special meaning for Fit values:
0: no good fit was obtained at all and the average values and
their associated uncertainties are obtained from the
`second' best values
1: then only 1 good value was obtained. The average values refer
to the good fit only, while the estimated uncertainties
are obtained from the 1-good and 6-`second' best values
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Acknowledgements: Yuen Keong Ng
(End) Patricia Bauer [CDS] 10-Nov-1997