# # Program information file # PROGRAM_ID 2021B016 PROGRAM_TITLE A new [Fe II] 17.94 micron emission line gas-phase mass-loss rate estimator for Red Supergiants - 2021B PROGRAM_INV1 Graham Harper PROGRAM_INV2 Matthew Richter PROGRAM_INV3 Thomas Greathouse PROGRAM_INV4 Edward Montiel PROGRAM_INV5 Anita Richards PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Mass loss has a major impact on the evolution of massive stars that terminate their lives in core-collapse supernovae. Existing mass-loss rate estimates for red supergiants can be uncertain by an order of magnitude and pose a severe problem for understanding this stage of evolution. The mass-loss rates adopted in stellar evolution codes affect the distribution of supergiants in the Hertzsprung-Russell Diagram and hence the interpretation of the stellar properties. We propose to refine a fundamentally new and robust gas-phase mass-loss rate estimator and also to greatly expand the number of empirically-based mass-loss rates. High-spectral resolution IRTF-TEXES observations of the optically-thin [Fe II] 17.94 micron emission line are required for a sample of oxygen-rich red supergiants covering a range of spectral-types and luminosities. Line fluxes will provide empirical measures of the energy fluxes that drive and heat the stellar outflows. The spectra will be used to obtain robust total [gas-phase] mass-loss rates, crucial input for stellar evolution codes. [Note that this is a continuation of a 2019B/2020A&B proposasl] PROGRAM_ABSTRACT_END