2009ApJ...692.1382D -
Astrophys. J., 692, 1382-1387 (2009/February-3)
Peculiar molecular envelope around the Post-AGB star IRAS 08544-4431.
DINH-V-TRUNG
Abstract (from CDS):
Circumbinary disks have been hypothesized to exist around a number of binary post-asymptotic giant branch (AGB) stars. Although most of the circumbinary disks have been inferred through the near-infrared (IR) excess, a few of them are strong emitters of molecular emission. Here we present high-angular resolution observations of the emission of 12CO and its isotopomer 13CO J = 2-1 line from the circumstellar envelope around the binary post-AGB star IRAS 08544-4431, which is one of the most prominent members of this class of objects. We find that the envelope is resolved in our observations and two separate components can be identified: (a) a central extended and strong component with very narrow linewidth between 2 and 6 km/s; (b) a weak bipolar outflow with expansion velocity up to 8 km/s. The central compact component possesses low and variable 12CO/13CO J = 2-1 line ratio, indicating optically thick emission of the main isotope. We estimate a molecular gas mass of 0.0047 M☉ for this component based on the optically thinner 13CO J = 2-1 line. We discuss the relation of the molecular envelope and the circumbinary disk inferred from near-IR excess and compare with other known cases where the distribution of molecular gas has been imaged at high angular resolution.
Abstract Copyright:
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Journal keyword(s):
circumstellar matter - ISM: molecules - stars: AGB and post-AGB - stars: individual: IRAS 08544-4431 - stars: mass loss
Simbad objects:
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