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J/A+AS/139/29       Empirical calibration of the 4000 A break    (Gorgas+, 1999)
Empirical calibration of the lambda 4000 A break
       Gorgas J., Cardiel N., Pedraz S., Gonzalez, J.J.
      <Astron. Astrophys. Suppl. Ser. 139, 29 (1999)>
      =1999A&AS..139...29G      (SIMBAD/NED BibCode)
ADC_Keywords: Stars, fundamental ; Effective temperatures ; Abundances, [Fe/H]

Keywords: stars: fundamental parameters - galaxies: stellar content -
          techniques: spectroscopic - stars: atmospheres

Description:
    Empirical fitting functions, describing the behaviour of the
    λ4000Å break in terms of effective temperature, metallicity
    and surface gravity, are presented. For this purpose, the break has
    been measured in 392 stars from the Lick/IDS Library. We have followed
    a very detailed error treatment in the reduction and fitting
    procedures, allowing for a reliable estimation of the break
    uncertainties. This calibration can be easily incorporated into
    stellar population models to provide accurate predictions of the break
    amplitude for, relatively old, composite systems. Table 1 lists the
    star sample, together with spectral types, adopted atmospheric
    parameters, break measurements, including errors, and residuals from
    the fitting functions.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat       101      392   Data sample and break measurements


See also:
   J/ApJS/94/687 : Old stellar populations. V. (Worthey+, 1994)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units     Label     Explanations

   1-  6  I6    ---       HD        ? HD (Cat. III/135) name
   7-  8  A2    ---       m_HD      Multiplicity extension of HD number
  10- 22  A13   ---       Name      Alternative name
  24- 36  A13   ---       SpType    Spectral type (1)
  38- 42  I5    K         Teff      ? Effective temperature
  44- 45  I2    ---       r_Teff    ? Source for effective temperature (2)
  47- 51  F5.3  cm/s2     log(g)    ? Logarithm of gravity
  53- 54  I2    ---       r_log(g)  ? Source for logarithm of gravity (2)
  56- 60  F5.2  Sun       [Fe/H]    ? Metallicity
  62- 63  I2    ---       r_[Fe/H]  ? Source for metallicity (2)
  65- 69  F5.3  ---       D4000     4000 A break
  71- 75  F5.3  ---       e_D4000   Error on 4000 A break (3)
  77- 82  F6.3  ---       Res       ? Residual from the fitting functions (4)
  84- 99  A16   ---       Runs      Runs in which the star was observed (5)
     101  A1    ---       Comm      Comments on individual stars (6)

Note (1): Sources for spectral types are, in order of preference:
           Worthey et al. (1994, Cat. J/ApJS/94/687)),
           Gorgas et al. (1993ApJS...86..153G),
           the Bright Star Catalog (Hoffleit & Jaschek, 1982, Cat. V/50) and
           the SIMBAD database.
           For the cluster stars (except for Coma and  Hyades) we list positions
           in the HR diagram (SGB: subgiant branch; GB: giant branch;
           HB: horizontal branch, red clump stars; AGB: asymptotic giant branch)
Note (2): Atmospheric parameters are taken from the electronic table of
           Worthey et al (1994, Cat. J/ApJS/94/687), with the following
           additional sources and modifications:
           1: Cayrel de Strobel et al. (1997A&AS..124..299C, Cat. III/200)
           2: Alonso et al. (1996, Cat. J/A+AS/117/227)
           3: Gratton et al. (1996, Cat. J/A+A/314/191)
           4: Mean from sources 1, 2 and 3
           5: Mean from sources 1 and 2
           6: Mean from sources 1 and 3
           7: Thevenin (1998BICDS.in.press.T)
           8: Marsakov and Shevelev (1995BICDS..47...13M, Cat. V/89)
           9: Gies and Lambert (1992ApJ...387..673G)
          10: Zakhozhaj and Shaparenko (1996, Cat. J/other/KFNT/12.20)
          11: Dyck et al. (1996AJ....111.1705D)
          12: Computed from the indices Fe5270 and Fe5335 using the fitting
               functions of Gorgas et al. (1993ApJS...86..153G) (in terms
               of (V-K))
          13: Computed from the indices Fe5270 and Fe5335 using the fitting
               functions of Worthey et al. (1994, Cat. J/ApJS/94/687)
               (in terms of Teff)
          14: Computed from the index Fe5270 using the fitting functions of
               Worthey et al. (1994, Cat. J/ApJS/94/687)) (in terms of Teff)
          15: From spectral type using table III of Johnson
               (1966ARA&A...4..193J)
          16: Extrapolation in the relation Teff versus spectral type of
               Ridgway et al. (1980ApJ...235..126R) (these temperatures differ
               from those given by Worthey et al. (1994, Cat. J/ApJS/94/687))
Note (3): Total random errors in the lambda 4000 A break measurements

Note (4): Residuals from the derived fitting functions (observed minus
           predicted)
Note (5): Run number(s) in which the star was observed. Number of repeated
           observations within each run is giving in parenthesis
Note (6): Stars not used to derive the empirical functions are marked with:
           a: Non cluster members (see Gorgas et al., 1993ApJS...86..153G)
           b: Lacking required atmospheric parameters
           c: Emission-line supergiant


Acknowledgements: Javier Gorgas 

(End)                    Javier Gorgas [UCM], Patricia Bauer [CDS]   18-May-1999