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 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 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 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 1995BICDS..47...13M, Cat. V/89)
9: Gies and Lambert (1992ApJ...387..673G 1992ApJ...387..673G)
10: Zakhozhaj and Shaparenko (1996, Cat. J/other/KFNT/12.20)
11: Dyck et al. (1996AJ....111.1705D 1996AJ....111.1705D)
12: Computed from the indices Fe5270 and Fe5335 using the fitting
functions of Gorgas et al. (1993ApJS...86..153G 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 1966ARA&A...4..193J)
16: Extrapolation in the relation Teff versus spectral type of
Ridgway et al. (1980ApJ...235..126R 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 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