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ALMA sub-mm maser and dust distribution of VY Canis Majoris

A. M. S. Richards ; C. M. V. Impellizzeri ; E. M. Humphreys ; C. Vlahakis ; Wouter Vlemmings (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; A. Baudry ; Elvire De Beck (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; L. Decin ; S. Etoka ; M. D. Gray ; G. M. Harper ; T. R. Hunter ; P. Kervella ; F. Kerschbaum ; I. McDonald ; G. Melnick ; Sebastien Muller (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; D. Neufeld ; Eamon O'Gorman (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; S. Y. Parfenov ; A. B. Peck ; H. Shinnaga ; A. M. Sobolev ; L. Testi ; L. Uscanga ; A. Wootten ; J. A. Yates ; A. Zijlstra
Astronomy and Astrophysics (0004-6361). Vol. 572 (2014),
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: stars: individual: VY CMa, supergiants, stars: mass-loss, masers



Denna post skapades 2015-01-16. Senast ändrad 2015-01-27.
CPL Pubid: 210899

 

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