IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2023A024 PROGRAM_TITLE High-resolution IR observations of 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 project, we want to continue our study of 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. Mira-type AGB stars show notable mass losses that cause the formation of a molcular layer and dusty envelope around the central star. In the inner molecular layer small molecules like 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, like varying radiation intensity and periodic shocks. Molecules such as SiO and TiO are ideal probes to study the dynamical behaviour of the molecular layer and help to determine the physical causes of these changes. Previous and ongoing observations have shown that SiO spectra can be successfully used to study the dynamics of these objects. Also the recent detection of TiO in Chi Cyg using TEXES on IRTF has been confirmed and it could be shown that also this molcule can be used to study the dynamics. The periode times of the observed variable stars are between 332 days [o Cet] and 470 days [IK Tau] and thus require at least 3 semester of observing time to fully cover stellar pulsation for all the investigated sources. The observations can only be carried out with the TEXES instrument at the IRTF in high-resolution mode [R =100,000] as we want to have comparable spectra for all stellar phases studied. PROGRAM_ABSTRACT_END