Title: Metal-rich carbon stars in the Sagittarius dwarf spheroidal galaxy
Authors: Lagadec, Eric ×
Zijlstra, Albert A
Sloan, G. C
Wood, Peter R
Matsuura, Mikako
Bernard-Salas, Jeronimo
Blommaert, Joris
Cioni, M. -R. L
Feast, M. W
Groenewegen, M. A. T
Hony, Sacha
Menzies, J. W
van Loon, J. Th
Whitelock, P. A #
Issue Date: Jun-2009
Publisher: Wiley-blackwell publishing, inc
Series Title: Monthly notices of the royal astronomical society vol:396 issue:1 pages:598-608
Abstract: We present spectroscopic observations from the Spitzer Space Telescope of six carbon-rich asymptotic giant branch (AGB) stars in the Sagittarius dwarf spheroidal galaxy (Sgr dSph) and two foreground Galactic carbon stars. The band strengths of the observed C2H2 and SiC features are very similar to those observed in Galactic AGB stars. The metallicities are estimated from an empirical relation between the acetylene optical depth and the strength of the SiC feature. The metallicities are higher than those of the Large Magellanic Cloud, and close to Galactic values. While the high metallicity could imply an age of around 1 Gyr, for the dusty AGB stars, the pulsation periods suggest ages in excess of 2 or 3 Gyr. We fit the spectra of the observed stars using the DUSTY radiative transfer model and determine their dust mass-loss rates to be in the range 1.0-3.3 x 10(-8) M-circle dot yr(-1). The two Galactic foreground carbon-rich AGB stars are located at the far side of the solar circle, beyond the Galactic Centre. One of these two stars shows the strongest SiC feature in our present Local Group sample.
ISSN: 0035-8711
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Institute of Astronomy
× corresponding author
# (joint) last author

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