ALMA sub-mm maser and dust distribution of VY Canis Majoris
Journal article, 2014
Aims. Cool, evolved stars have copious, enriched winds. Observations have so far not fully constrained models for the shaping and acceleration of these winds. We need to understand the dynamics better, from the pulsating stellar surface to similar to 10 stellar radii, where radiation pressure on dust is fully effective. Asymmetric nebulae around some red supergiants imply the action of additional forces. Methods. We retrieved ALMA Science Verification data providing images of sub-mm line and continuum emission from VY CMa. This enables us to locate water masers with milli-arcsec accuracy and to resolve the dusty continuum. Results. The 658, 321, and 325 GHz masers lie in irregular, thick shells at increasing distances from the centre of expansion. For the first time this is confirmed as the stellar position, coinciding with a compact peak offset to the NW of the brightest continuum emission. The maser shells overlap but avoid each other on scales of up to 10 au. Their distribution is broadly consistent with excitation models but the conditions and kinematics are complicated by wind collisions, clumping, and asymmetries.
stars: mass-loss
stars: individual: VY CMa
supergiants
masers
Author
A. M. S. Richards
University of Manchester
C. M. V. Impellizzeri
Atacama Large Millimeter-submillimeter Array (ALMA)
National Radio Astronomy Observatory
E. M. Humphreys
European Southern Observatory (ESO)
C. Vlahakis
Atacama Large Millimeter-submillimeter Array (ALMA)
Wouter Vlemmings
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
A. Baudry
Laboratoire d'Astrophysique de Bordeaux
Centre national de la recherche scientifique (CNRS)
Elvire De Beck
Chalmers, Earth and Space Sciences, Onsala Space Observatory
L. Decin
KU Leuven
S. Etoka
University of Hamburg
M. D. Gray
University of Manchester
G. M. Harper
Trinity College Dublin
T. R. Hunter
National Radio Astronomy Observatory
P. Kervella
Paris Diderot University
University of Chile (UCH)
UMI-FCA
F. Kerschbaum
University of Vienna
I. McDonald
University of Manchester
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
Sebastien Muller
Chalmers, Earth and Space Sciences, Onsala Space Observatory
D. A. Neufeld
Johns Hopkins University
Eamon O Gorman
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
S. Y. Parfenov
Ural Federal University
A. B. Peck
National Radio Astronomy Observatory
H. Shinnaga
National Astronomical Observatory of Japan
A. M. Sobolev
Ural Federal University
L. Testi
European Southern Observatory (ESO)
L. Uscanga
National Observatory of Athens
A. Wootten
National Radio Astronomy Observatory
J. A. Yates
University College London (UCL)
A. Zijlstra
University of Manchester
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 572 L9Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201425024