Access to Astronomical Catalogues

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      (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:

       FileName      Lrecl  Records   Explanations

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            40       61  *F & G stars on or near the main sequence data
                                (correction for absolute visual magnitude)
table6            40      128  *F & G stars on or near the sub-giant branch data
                                (correction for absolute visual magnitude)
table7            40       76  *F & G stars on or near the main sequence data
                                (as in table3 but with Hipparcos parallax)
table8            40      113  *F & G stars on or near the sub-giant branch data
                                (as in table4 but with Hipparcos parallax)


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) correction applied (n=4, sigma_pi/pi=0.15; Hanson
  (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

See also:
   J/A+A/275/101 : Chemical evolution of the galactic disk I. (Edvardsson+ 1993)


Byte-by-byte Description of file: table*

   Bytes Format Units     Label     Explanations

   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)

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


Acknowledgements: Yuen Keong Ng 

(End)                                         Patricia Bauer [CDS]   10-Nov-1997