# # Program information file # PROGRAM_ID 2022B064 PROGRAM_TITLE High-resolution IR observations of TiO and SiO in Mira-type variables at different stellar phases PROGRAM_INV1 Guido W. Fuchs PROGRAM_INV2 Eileen Doering PROGRAM_INV3 David Gobrecht PROGRAM_INV4 Thomas K. Greathouse PROGRAM_INV5 Rohini S. Giles PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG In this work, we will study the dynamics of the inner molecular envelope of prototypical regular M- and S-type pulsating stars, like chi Cyg, o Cet, R Cas and IK Tau. These Mira-type AGB stars show notable mass loss that causes the formation of a molecular layer and dusty envelope around the central star. In the inner molecular layer small molecules such as SiO, TiO, and other species made of refractory materials are formed. The pulsation of the stellar photosphere influences the surrounding molecular layer in various ways, e.g., by varying the radiation intensity and by periodic shocks. The molecules SiO and TiO are ideal probes to study the dynamical behavior of the molecular layer and to determine the physical parameters of these changes. The TEXES instrument on IRTF in its high resolution mode [R =100,000] enables line shape analysis of the observed molecular spectra. With this data the physical and chemical conditions, as well as the coupling between the motion of the photosphere and the molecular layer will be investigated. In addition, possible correlations with the optical dimming of these stars will be investigated. PROGRAM_ABSTRACT_END