Issue |
A&A
Volume 388, Number 1, June II 2002
|
|
---|---|---|
Page(s) | 309 - 319 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20020439 | |
Published online | 28 May 2002 |
A revised HRD for individual components of binary
systems from BaSeL
synthetic photometry
Influence of interstellar extinction and stellar rotation
Observatório Astronómico da Universidade de Coimbra, Santa Clara, 3040 Coimbra, Portugal
Corresponding author: E. Lastennet, lastenne@mat.uc.pt
Received:
22
February
2002
Accepted:
19
March
2002
Johnson BVRI photometric data for individual components of binary systems
have been provided by ten Brummelaar et al. ([CITE]).
This is essential because non-interacting binaries can be considered as two
single stars and therefore play a critical role in testing and calibrating
single-star stellar evolution sets of isochrones and the implicit theory.
While they derived the effective temperature (Teff) from their estimated
spectral type, we infer metallicity-dependent Teff from a minimizing
method fitting the ,
and
colours.
For this purpose, a grid of 621 600 flux distributions were computed from the Basel
Stellar Library (BaSeL 2.2) of model-atmosphere spectra, and their theoretical colours
compared with the observed photometry. The BaSeL colours show a
very good agreement with the BVRI metallicity-dependent empirical calibrations of
Alonso et al. ([CITE]), with the temperatures being different by
in the range
4000–8000 K for dwarf stars.
Before deriving the metallicity-dependent Teff from the BaSeL models,
we paid particular attention to the influence of reddening and stellar rotation.
We inferred the reddening from two different methods: (i) the MExcessNg code v1.1
(Méndez & van Altena [CITE]) and (ii) neutral hydrogen column density data.
A comparison of both methods shows a good agreement for the sample located
inside a local sphere of ~500 pc, but we point out a few directions where
the MExcess model overestimates the
) colour excess.
Influence of stellar rotation on the BVRI colours can be neglected except for
5 stars with large
, the maximum effect on temperature being less than 5%.
Our final determinations provide effective temperature estimates for each
component. They are in good agreement with previous spectroscopic determinations
available for a few primary components, and with ten Brummelaar et al. below
~10 000 K. Nevertheless, we obtain an increasing disagreement with their
temperatures beyond 10 000 K.
Finally, we provide a revised Hertzsprung-Russell diagram (HRD) for
the systems with the more accurately determined temperatures.
Key words: stars: fundamental parameters / stars: binaries: visual / stars: abundances / stars: rotation / stars: Hertzsprung-Russell (HR) and C-M diagrams / ISM: dust, extinction
© ESO, 2002
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