ALMA observations of TiO2 around VY Canis Majoris
Artikel i vetenskaplig tidskrift, 2015

Context. Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. To date, gas phase TiO2 has been detected only in the complex environment of the red supergiant VY CMa. Aims. We aim to constrain the distribution and excitation of TiO2 around VY CMa in order to clarify its role in dust formation. Methods. We analyse spectra and channel maps for TiO2 extracted from ALMA science verification data. Results. We detect 15 transitions of TiO2, and spatially resolve the emission for the first time. The maps demonstrate a highly clumpy, anisotropic outflow in which the TiO2 emission likely traces gas exposed to the stellar radiation field. An accelerating bipolar-like structure is found, oriented roughly east-west, of which the blue component runs into and breaks up around a solid continuum component. A distinct tail to the south-west is seen for some transitions, consistent with features seen in the optical and near-infrared. Conclusions. We find that a significant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa.

Stars: mass-loss

Submillimeter: stars

Supergiants

Circumstellar matter

Stars: individual: VY Canis Majoris

Författare

Elvire De Beck

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Wouter Vlemmings

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

Sebastien Muller

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

John H Black

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

Eamon O Gorman

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

A. M. S. Richards

University of Manchester

A. Baudry

Centre national de la recherche scientifique (CNRS)

Laboratoire d'Astrophysique de Bordeaux

Matthias Maercker

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

L. Decin

Universiteit Van Amsterdam

KU Leuven

E. M. Humphreys

European Southern Observatory (ESO)

Astronomy and Astrophysics

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

Vol. 580 A36

Magnetic fields and the outflows during the formation and evolution of stars (OUTFLOWMAGN)

Europeiska kommissionen (FP7), 2014-05-01 -- 2019-04-30.

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

Infrastruktur

Onsala rymdobservatorium

DOI

10.1051/0004-6361/201525990

Mer information

Senast uppdaterat

2018-09-07