ALMA observations of TiO2 around VY Canis Majoris
Journal article, 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

Author

Elvire De Beck

Chalmers, Earth and Space Sciences, Onsala Space Observatory

Wouter Vlemmings

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Sebastien Muller

Chalmers, Earth and Space Sciences, Onsala Space Observatory

John H Black

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Eamon O Gorman

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

A. M. S. Richards

University of Manchester

A. Baudry

Centre national de la recherche scientifique (CNRS)

Laboratoire d'Astrophysique de Bordeaux

Matthias Maercker

Chalmers, Earth and Space Sciences, Onsala Space Observatory

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

L. Decin

University of 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)

European Commission (FP7), 2014-05-01 -- 2019-04-30.

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

Infrastructure

Onsala Space Observatory

DOI

10.1051/0004-6361/201525990

More information

Latest update

9/7/2018 1