Issue |
A&A
Volume 412, Number 1, December II 2003
|
|
---|---|---|
Page(s) | 91 - 95 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20031426 | |
Published online | 25 November 2003 |
Theoretical isochrones for the Δa photometric system
1
Instituto de Astrofísica de Andalucía, CSIC, Apartado 3004, 18080 Granada, Spain
2
Institut für Astronomie der Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
3
Zentraler Informatikdienst der Universität Wien, Universitätsstr. 7, 1010 Wien, Austria
Corresponding author: A. Claret, claret@iaa.es
Received:
15
May
2003
Accepted:
20
August
2003
We have calculated theoretical isochrones for the
photometric system to derive astrophysical parameters such
as the age, reddening and distance modulus for open clusters. The
system samples the flux depression at 520 nm which
is highly efficient to detect chemically peculiar (CP) objects of
the upper main sequence. The evolutionary status of CP stars is still
a matter of debate and very important to test, for example,
the dynamo and diffusion theories. In fact, the
dynamo or fossil origin of the magnetic fields present in this kind of
star is still not clear.
Using the stellar evolutionary models by
Claret ([CITE]), a grid of isochrones with different initial chemical compositions
for the
system was generated.
The published data of 23 open clusters were used to fit these
isochrones with astrophysical parameters (age, reddening and distance modulus)
from the literature. As an additional test,
isochrones with the same parameters for Johnson UBV data of these open clusters
were also considered. The fits show a good agreement between the observations and
the theoretical grid. We find that the accuracy of fitting isochrones to
data without the knowledge of the cluster parameters is between 5 and 15%.
Key words: open clusters and associations: general / stars: fundamental parameters
© ESO, 2003
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