X Herculis and TX Piscium: two cases of ISM interaction with stellar winds observed by Herschel
Journal article, 2011

The asymptotic giant branch (AGB) stars X Her and TX Psc have been imaged at 70 and 160 μm with the PACS instrument onboard the Herschel satellite, as part of the large MESS (Mass loss of Evolved StarS) guaranteed time key program. The images reveal an axisymmetric extended structure with its axis oriented along the space motion of the stars. This extended structure is very likely to be shaped by the interaction of the wind ejected by the AGB star with the surrounding interstellar medium (ISM). As predicted by numerical simulations, the detailed structure of the wind-ISM interface depends upon the relative velocity between star+wind and the ISM, which is large for these two stars (108 and 55 km s-1 for X Her and TX Psc, respectively). In both cases, there is a compact blob upstream whose origin is not fully elucidated, but that could be the signature of some instability in the wind-ISM shock. Deconvolved images of X Her and TX Psc reveal several discrete structures along the outermost filaments, which could be Kelvin-Helmholtz vortices. Finally, TX Psc is surrounded by an almost circular ring (the signature of the termination shock?) that contrasts with the outer, more structured filaments. A similar inner circular structure seems to be present in X Her as well, albeit less clearly.

stars: AGB and post-AGB

ISM: general

stars: mass-loss

infrared: stars

stars: carbon


A. Jorissen

Université libre de Bruxelles (ULB)

A. Mayer

University of Vienna

S. Van Eck

Université libre de Bruxelles (ULB)

R. Ottensamer

Technische Universität Graz

University of Vienna

F. Kerschbaum

University of Vienna

T. Ueta

University of Denver

Per Bergman

Chalmers, Earth and Space Sciences, Onsala Space Observatory

Jadl Blommaert

KU Leuven

L. Decin

KU Leuven

M. A. T. Groenewegen

Royal Observatory of Belgium

J. Hron

University of Vienna

W. Nowotny

University of Vienna

Hans Olofsson

Chalmers, Earth and Space Sciences, Onsala Space Observatory

T. Posch

University of Vienna

Loránt Olivér Sjouwerman

National Radio Astronomy Observatory Socorro

B. Vandenbussche

KU Leuven

C. Waelkens

KU Leuven

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 532 A135

Subject Categories

Astronomy, Astrophysics and Cosmology


Basic sciences



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