Dissecting the AGB star L2 Puppis: a torus in the making

• Main Authors: Lykou, F, Klotz, D, Paladini, C, Hron, J, Zijlstra, A. A, Kluska, J, Norris, B. R. M, Tuthill, P. G, Ramstedt, S, Lagadec, E, Wittkowski, M, Maercker, M, Meisner, J, Mayer, A
• Format: Journal Article
• Language: English
• Published: 17-03-2015
• Subjects: Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.1503.05031

A&A 576, A46 (2015) The circumstellar environment of L2 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. 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 $\rm\mu m$) on the NACO/VLT, both in imaging
and polarimetric modes. The aperture-masking images of L2 Pup at 2.30 $\rm\mu
m$ show a resolved structure that resembles a toroidal structure with a major
axis of ~140 milliarcseconds (mas) and an east-west orientation. Two clumps can
be seen on either side of the star, ~65 mas from the star, beyond the edge of
the circumstellar envelope (estimated diameter is ~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 $\rm\mu m$ 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 km s$^{-1}$ as suggested by the SiO maser profile, we
estimate a stellar mass of 0.7 M$_\odot$.}