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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/4015

Title: The variable mass loss of the AGB star WX Piscium as traced by the CO J=1-0 through 7-6 lines and the dust emission
Authors: Decin, Leen
Hony, S.
de Koter, Alex
Molenberghs, Geert
Dehaes, Sofie
Markwick-Kemper, Francisca
Issue Date: 2007
Citation: ASTRONOMY & ASTROPHYSICS, 475(1). p. 233-242
Abstract: Context. Low and intermediate mass stars lose a significant fraction of their mass through a dust-driven wind during the Asymptotic Giant Branch (AGB) phase. Recent studies show that winds from late-type stars are far from being smooth. Mass-loss variations occur on different time scales, from years to tens of thousands of years. The variations appear to be particularly prominent towards the end of the AGB evolution. The occurrence, amplitude and time scale of these variations are still not well understood. Aims. The goal of our study is to gain insight into the structure of the circumstellar envelope (CSE) of WX Psc and map the possible variability of the late-AGB mass-loss phenomenon. Methods. We have performed an in-depth analysis of the extreme infrared AGB star WX Psc by modeling (1) the CO J = 1-0 through 7-6 rotational line profiles and the full spectral energy distribution (SED) ranging from 0.7 to 1300 m. We hence are able to trace a geometrically extended region of the CSE. Results. Both mass-loss diagnostics bear evidence of the occurrence of mass-loss modulations during the last similar to 2000 yr. In particular, WX Psc went through a high mass-loss phase (M similar to 5 x 10(-5) M-circle dot/yr) some 800 yr ago. This phase lasted about 600 yr and was followed by a long period of low mass loss (M similar to 5 x 10(-5) M-circle dot/yr). The present day mass-loss rate is estimated to be similar to 6 x 10-(6) M-circle dot/yr. Conclusions. The AGB star WX Psc has undergone strong mass-loss rate variability on a time scale of several hundred years during the last few thousand years. These variations are traced in the strength and profile of the CO rotational lines and in the SED. We have consistently simulated the behaviour of both tracers using radiative transfer codes that allow for non-constant mass-loss rates.
Notes: Katholieke Univ Leuven, Inst Astron, Dept Phys & Astron, B-3001 Louvain, Belgium. Univ Amsterdam, Sterrekundig Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France. Univ Hasselt, Ctr Stat, B-3590 Diepenbeek, Belgium. Univ Manchester, Sch Phys & Astron, Manchester M60 1QD, Lancs, England. Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA.Decin, L, Katholieke Univ Leuven, Inst Astron, Dept Phys & Astron, Celestijnenlaan 200B, B-3001 Louvain, Belgium.Leen.Decin@ster.kuleuven.ac.be
URI: http://hdl.handle.net/1942/4015
DOI: 10.1051/0004-6361:20077737
ISI #: 000250480100021
ISSN: 1432-0746
Category: A1
Type: Journal Contribution
Validation: ecoom, 2008
Appears in Collections: Research publications

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