Dissecting the AGB star L-2 Puppis: a torus in the making
Artikel i vetenskaplig tidskrift, 2015

Aims. The circumstellar environment of L-2 Pup, an oxygen-rich semiregular variable, was observed to understand the evolution of mass loss and the shaping of ejecta in the late stages of stellar evolution. Methods. High-angular resolution observations from a single 8 m telescope were obtained using aperture masking in the near-infrared (1.64, 2.30 and 3.74 mu m) on the NACO/VLT, both in imaging and polarimetric modes. Results. The aperture-masking images of L-2 Pup at 2.30 mu m show a resolved structure that resembles a toroidal structure with a major axis of similar to 140 milliarcseconds (mas) and an east-west orientation. Two clumps can be seen on either side of the star, similar to 65 mas from the star, beyond the edge of the circumstellar envelope (estimated diameter is similar to 27 mas), while a faint, hook-like structure appear toward the northeast. The patterns are visible both in the imaging and polarimetric mode, although the latter was only used to measure the total intensity (Stokes I). The overall shape of the structure is similar at the 3.74 mu m pseudo-continuum (dust emission), where the clumps appear to be embedded within a dark, dusty lane. The faint, hook-like patterns are also seen at this wavelength, extending northeast and southwest with the central, dark lane being an apparent axis of symmetry. We interpret the structure as a circumstellar torus with inner radius of 4.2 au. With a rotation velocity of 10 kms(-1) as suggested by the SiO maser profile, we estimate a stellar mass of 0.7 M-circle dot.

circumstellar matter

stars: individual: L-2 Puppis

stars: evolution

methods: observational

techniques: high angular resolution

stars: AGB and post-AGB

Författare

F. Lykou

Universität Wien

D. Klotz

Universität Wien

C. Paladini

Universität Wien

Université libre de Bruxelles (ULB)

J. Hron

Universität Wien

A. Zijlstra

University of Manchester

J. Kluska

CNRS Centre National de la Recherche Scientifique

B. R. M. Norris

The University of Sydney

P. G. Tuthill

The University of Sydney

S. Ramstedt

Uppsala universitet

E. Lagadec

Université Nice Sophia Antipolis (UNS)

Cornell University

M. Wittkowski

European Southern Observatory (ESO)

Matthias Maercker

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

A. Mayer

Universität Wien

Astronomy and Astrophysics

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

Vol. 576 A46

Ämneskategorier

Astronomi, astrofysik och kosmologi

Infrastruktur

Onsala rymdobservatorium

DOI

10.1051/0004-6361/201322828