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A&A 399, 525-530 (2003)
DOI: 10.1051/0004-6361:20021802
Non-LTE abundances of magnesium, aluminum and sulfur in OB stars near the solar circle
S. Daflon1, K. Cunha1, V. V. Smith2 and K. Butler31 Observatório Nacional, Rua General José Cristino 77 CEP 20921-400, Rio de Janeiro, Brazil
e-mail: daflon@on.br;katia@on.br
2 Department of Physics, University of Texas at El Paso, El Paso, TX 79968-0515, USA
e-mail: verne@barium.physics.utep.edu
3 Institut für Astronomie und Astrophysik der Universität München, Scheinerstrasse 1, 81679 München, Germany
e-mail: butler@usm.uni-muenchen.de
(Received 15 October 2002 / Accepted 29 November 2002)
Abstract
Non-LTE abundances of magnesium, aluminum and sulfur are derived
for a sample of 23 low-
stars belonging to six northern
OB associations of the Galactic disk within 1 kpc of the
Sun. The abundances are obtained from the fitting of synthetic
line profiles to high resolution spectra. A comparison of our
results with HII region abundances indicates good agreement
for sulfur while the cepheid abundances are higher. The derived
abundances of Mg show good overlap with the cepheid results.
The aluminum abundances for OB stars are significantly below
the cepheid values. But, the OB star results show a dependence
with effective temperature and need further investigation.
The high Al abundances in the cepheids could be the result of
mixing. A discussion of the oxygen abundance in objects near
the solar circle suggests that the current mean galactic oxygen
abundance in this region is 8.6-8.7 and in agreement with the
recently revised oxygen abundance in the solar photosphere.
Meaningful comparisons of the absolute S, Al and Mg
abundances in OB stars with the Sun must await a reinvestigation
of these elements
with 3D hydrodynamical model atmospheres for the Sun.
No abundance gradients are found within the limited range in
galactocentric distances in the present study. Such variations
would be expected only if there were large metallicity gradients
in the disk.
Key words: stars: abundances -- stars: early-type
Offprint request: S. Daflon SIMBAD Objects
© ESO 2003