# # Program information file # PROGRAM_ID 2024A053 PROGRAM_TITLE Measuring the Physical Stellar Parameters and Accretion Rates of Young Stars with Planet Forming Disks. PROGRAM_INV1 Michael Connelley PROGRAM_INV2 Ellen Lee PROGRAM_INV3 Christian Flores PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG We propose to take SpeX and iSHELL spectra of a young stars that are the targets of a contemporary proposal to Subaru to do extreme AO with their new infrared wavefront sensor. The goal of the Subaru AO observation is to determine the youngest a star can be such that we can directly image planet forming disk structures. The goal of the IRTF observations is to place the AO images into the broader star formation context. High resolution K-band spectra with iSHELL will measure the temperature, gravity, rotation velocity, veiling disk emission, and stellar magnetic field. The temperature and gravity measurements allow us to infer the mass and age of the central star. Given the temperature and a SpeX SXD spectrum, we can fit the observed continuum with a stellar template to derive the extinction. The SXD spectrum also yields the Br gamma line flux, an important accretion tracer, which [combined with extinction, stellar mass, and radius of the star] enables us to measure the accretion rate. The key outputs of this program are the stellar age, stellar mass, extinction, and mass accretion rates, for each star individually. Knowing these values are key to interpreting the Subaru AO images to gain key insight on the planet forming process. PROGRAM_ABSTRACT_END