Dust-forming molecules in VY Canis Majoris (and Betelgeuse)

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
² Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, USA
³ Nicolaus Copernicus Astronomical Center, Rabiańska 8, 87-100 Toruń, Poland
⁴ I. Physikalisches Institut, Zülpicher Strasse 77, 50937 Köln, Germany
⁵ IRAM, 300 rue de la Piscine, 38406 Saint-Martin d’Hères, France

Abstract

The formation of inorganic dust in circumstellar environments of evolved stars is poorly understood. Spectra of molecules thought to be most important for the nucleation, i.e. AlO, TiO, and TiO₂, have been recently detected in the red supergiant VY CMa. These molecules are effectively formed in VY CMa and the observations suggest that non-equilibrium chemistry must be involved in their formation and nucleation into dust. In addition to exploring the recent observations of VY CMa, we briefly discuss the possibility of detecting these molecules in the “dust-poor” circumstellar environment of Betelgeuse.