Continuum emission around AGB stars at 1.2 mm

Abstract

It is generally acknowledged that the mass loss of Asymptotic Giant Branch (AGB) stars undergoes variations on different time scales. We constructed models for the dust envelopes for a sample of AGB stars to assess whether mass-loss variations influence the spectral energy distribution (SED). To constrain the variability, extra observations at millimetre wavelengths (1.2 mm) were acquired. From the analysis of the dust models, two indications for the presence of mass-loss variations can be found, being (1) a dust temperature at the inner boundary of the dust envelope that is far below the dust condensation temperature and (2) an altered density distribution with respect to rho(r) \propto r^{-2} resulting from a constant mass-loss rate. For 5 out of the 18 studied sources a two-component model of the envelope is required, consisting of an inner region with a constant mass-loss rate and an outer region with a less steep density distribution. For one source an outer region with a steeper density distribution was found. Moreover, in a search for time variability in our data set at 1.2 mm, we found that WX Psc shows a large relative time variation of 34% which might partially be caused by variable molecular line emission.

arXiv commentAccepted for publication in MNRAS; 16 pages, 19 figures

References in corpus (11)

• Self-similarity and scaling behavior of IR emission from radiatively heated dust: I. Theory
• Imaging the circumstellar envelopes of AGB stars
• User Manual for DUSTY
• Origin of quasi-periodic shells in dust forming AGB winds
• Towards the automated reduction and calibration of SCUBA data from the James Clerk Maxwell Telescope
• Properties of detached shells around carbon stars: Evidence of interacting winds
• Solar-Like Cycle in Asymptotic Giant Branch Stars
• The Case for Asymmetric Dust Around a C-Rich AGB star
• A multi-wavelength study of the oxygen-rich AGB star CIT 3: Bispectrum speckle interferometry and dust-shell modelling
• Discovery of an edge-on dust disk around the [WC10] central star CPD-568032
• The Dying Wind Around HD 56126, A Post-AGB Carbon Star

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