2005A&A...433..553L -
Astronomy and Astrophysics, volume 433, 553-564 (2005/4-2)
Dust temperature and density profiles in the envelopes of AGB and post-AGB carbon stars from mid-infrared observations.
LAGADEC E., MEKARNIA D., DE FREITAS PACHECO J.A. and DOUGADOS C.
Abstract (from CDS):
First mid-infrared images of a sample of AGB and post-AGB carbon stars (V Hya, IRC+10216, CIT 6 and Roberts 22) obtained at the ESO-La Silla Observatory (Chile) are reported. CIT 6 presents a cometary-like feature clearly seen in the 9.7µm image, Roberts 22 shows an envelope slightly elongated in the north-east direction while images of V Hya and IRC+10216 are roughly spherically symmetric. Using an inversion technique, the dust emissivity was derived from the observed intensity profiles, allowing a determination of the grain temperature and density distributions inside the envelope for these stars. Dust masses and mass-loss rates were estimated for V Hya and IRC+10216. Our results are comparable to those obtained in previous studies if dust grains have dimensions in the range ∼0.01-0.2µm. Color maps suggest the presence of temperature inhomogeneities in the central regions of the dust envelopes. In the case of V Hya, an eccentric hot point, whose direction coincides with the jet previously seen in [SII] emission, suggests that we are observing material ejected in a previous mass-loss event. Bipolar lobes are clearly seen in the color maps of Roberts 22 and IRC+10216.
Abstract Copyright:
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Journal keyword(s):
stars: AGB and post-AGB - stars: circumstellar matter - stars: mass-loss - stars: imaging - infrared: stars
Simbad objects:
6
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