Bibcode
Dufton, P. L.; Ryans, R. S. I.; Trundle, C.; Lennon, D. J.; Hubeny, I.; Lanz, T.; Allende Prieto, C.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 434, Issue 3, May II 2005, pp.1125-1137
Advertised on:
5
2005
Revista
Número de citas
69
Número de citas referidas
60
Descripción
High-resolution UCLES/AAT spectra are presented for nine B-type
supergiants in the SMC, chosen on the basis that they may show varying
amounts of nuclear-synthetically processed material mixed to their
surface. These spectra have been analysed using a new grid of
approximately 12 000 non-LTE line blanketed tlusty model atmospheres to
estimate atmospheric parameters and chemical composition. The abundance
estimates for O, Mg and Si are in excellent agreement with those deduced
from other studies, whilst the low estimate for C may reflect the use of
the C II doublet at 4267 Å. The N estimates are approximately an
order of magnitude greater than those found in unevolved B-type stars or
H II regions but are consistent with the other estimates in AB-type
supergiants. These results have been combined with results from a
unified model atmosphere analysis of UVES/VLT spectra of B-type
supergiants (Trundle et al. 2004, A&A, 417, 217) to discuss the
evolutionary status of these objects. For two stars that are in common
with those discussed by Trundle et al., we have undertaken a careful
comparison in order to try to understand the relative importance of the
different uncertainties present in such analyses, including
observational errors and the use of static or unified models. We find
that even for these relatively luminous supergiants, tlusty models yield
atmospheric parameters and chemical compositions similar to those
deduced from the unified code fastwind.