Phénomènes Physiques et
Modèles
Mathématiques en Sciences de l'Univers
Le séminaire a lieu le vendredi 18 juin 2004 de 14h00 à
15h00
dans la salle de réunion
du PHC (Observatoire de Nice).
Subgiant stars
for galactic evolution
Bengt Edvardsson,
Observatoire d'Uppsala, Suède
Studies of galactic chemical evolution are often made using
nearby dwarf stars for the galactic disk and giant stars for studies of
more distant regions.
Dwarf stars are, however, rather faint and results for giants are often
less accurate
due to modelling uncertainties and effects of the dredge-up of
internally processed matter to the
surface.
We have therefore made an exploratory study of the usefulness of
subgiant branch stars for galactic evolution.
The subgiant ages are more accurate than those of both giants and
dwarfs,
and the abundance results turn out to be as accurate as for dwarfs,
with the surprise that traces of CN cycling may appear already on the
subgiant branch.