# # Program information file # PROGRAM_ID 2021A005 PROGRAM_TITLE A new [Fe II] 17.94 micron emission line gas-phase mass-loss rate estimator for Red Supergiants - 2021A PROGRAM_INV1 Graham Harper PROGRAM_INV2 Matthew Richter PROGRAM_INV3 Thomas Greathouse PROGRAM_INV4 Edward Guinan PROGRAM_INV5 Edward Montiel 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 massive red supergiants pose a severe %problem to our understanding of this stage of evolution because they can be uncertain by an order-of-magnitude. The mass-loss rates adopted in stellar evolution codes affect the distribution of supergiants in the Hertzsprung-Russell Diagram and hence the interpretation of stellar properties at a given location. 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 and widths 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 proposal] PROGRAM_ABSTRACT_END