2009
Ref: ASTROimport-487

Metal-rich carbon stars in the Sagittarius dwarf spheroidal galaxy

Lagadec, E. ; Zijlstra, A. A. ; Sloan, G. C. ; Wood, P. R. ; Matsuura, M. ; Bernard-Salas, J. ; Blommaert, J. A. D. L. ; Cioni, M.-R. L. ; Feast, M. W. ; Groenewegen, M. A. T. ; Hony, S. ; Menzies, J. W. ; van Loon, J. T. ; Whitelock, P. A.


published in Monthly Notices of the Royal Astronomical Society, 396, pp. 598-608 (2009)

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 1Gyr, 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 × 10-8Msolaryr-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.

DOI: 10.1111/j.1365-2966.2009.14736.x
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The record appears in these collections:
Royal Observatory of Belgium > Astronomy & Astrophysics
Science Articles > Peer Reviewed Articles



 Record created 2016-07-01, last modified 2016-07-01