IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021B059 PROGRAM_TITLE From Molecules to dust - silicon and metal oxide seeds towards the late-type star VY Canis Majoris PROGRAM_INV1 Guido Fuchs PROGRAM_INV2 Eileen Doering PROGRAM_INV3 Thomas Giesen PROGRAM_INV4 Thomas Greathouse PROGRAM_INV5 John Lacy PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG At the end of their lifetime stars eject large amounts of material into space. In this way cosmic dust is formed, but the formation process is still not well understood - especially for M-type stars. VY Canis Majoris is a M-type red supergiant of spectacular size, up to 3000 times the sun radius, that produces strong stellar winds. Spectral line surveys at radio wavelengths have revealed ~25 different molecular species in the vicinity of this star and the chemical content reveals a surprising variety of species. Chemistry in stellar shells is to a large extent a non-LTE chemistry with competing processes [oxidation, clustering, etc.] which can only be understood by simultaneous observation of all relevant chemical components. With the TEXES instrument at the IRTF telescope infrared spectroscopy offers a unique opportunity to study this chemistry in the mid-infrared 'fingerprint' region at high spectral resolution. Thus, we would like to continue our TEXES molecular line survey that started in the 2018B semester. This time we aim for the 8.4+/-0.1um and 10.6+/-0.5um region to observe TiO and Al2O, as well as NH3 and SiO. Al2O would be a first-time observation, TiO a first mid-IR observation. As a laboratory group we have unique spectroscopic IR data of Al2O available. Both molecules, as well as SiO are important to understand dust formation in late-M type stars. SiO and NH3 measurements will be performed to make line shape analysis, to determine their spatial distribution, abundances and, in case of SiO, to improve the accuracy of the isotopic ratio of Si in the stellar envelope. PROGRAM_ABSTRACT_END