Dying Stars:
Dust-forming molecules in VY CMa
The formation of inorganic (silicates and alumina) dust in circumstellar environments of evolved stars is poorly understood. The Submillimeter Array (SMA) was the first instrument to observe rotational spectra of molecules thought to be most important for the nucleation of dust at elevated temeratures, i.e. close to the stellar photospheres. For the first time, rotational transitions of TiO and TiO2 were observed in an astronomical object. 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.
The Submillimter Array detected for the first time cool gas containing titanium oxides (TiO and TiO2). The oxides are thought to be important for dust condensation and were observed toward the red supergiant, VY CMa. The color image is based on optical observations of the complex nebula surrounding VY CMa.The smaller circle show the region where titanium oxides have been detected.
References:
Kamiński et al.,
Pure rotational spectra of TiO and TiO2 in VY Canis Majoris, 2013, A&A 551
Other Resources:
https://www.mpg.de/7066175/vy_canis_majoris_titanium_oxide
