# # Program information file # PROGRAM_ID 2021B018 PROGRAM_TITLE Hidden Binaries in the Beta Pictoris Moving Group PROGRAM_INV1 Rena Lee PROGRAM_INV2 Eric Gaidos PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG The most numerous stars in our galaxy, M dwarfs, are resistant to most age estimators [e.g., asteroseimology, Li dating, metallicity], complicating the study of their evolution. The only viable method for dating individual M dwarfs lies in rotation and its proxies. We are constructing a gyrochronological relation for M dwarfs from the pre- to late main sequence, to advance our understanding of their rotational and PMS evolution. Complicating the gyrochronology further, binarity is known to perturb the rotational evolution of M dwarfs, especially at the end of the PMS phase as disks dissipate, and ~40% of M dwarfs have been found in multi-star systems. The Beta Pictoris Moving Group at an age of ~22 Myr presents an unparalleled opportunity to study PMS M dwarfs, since it is nearby [within ~50 pc], and targets are comparatively bright [median K=9]. A catalog of candidate BPMG members has been compiled from the literature. Using iSHELL in K-gas mode, with the 0'.375 slit and methane isotopologue gas cell, we are observing the candidate BPMG M dwarfs with the concurrent goals of obtaining RV measurements to confirm membership based on their space motions [Gagne et al., 2018], and to identify hidden spectroscopic binaries to explain the observed scatter in the rotation periods of BPMG M dwarfs. RV precisions to a few km/s can be achieved, and SB2s with contrast ratios down to 0.1 can be detected. Component RVs can be determined via the 2D cross-correlation method [Kolbl et al., 2015]. SB1s will be detected using the gas cell lines as a fixed wavelength reference, measuring the wavelength shift, and performing a barycenter correction. Spectra will be extracted using the pychell data reduction package [Cale et al., 2019]; cross-correlations and absolute wavelength calibration will be performed using additional custom Python scripts. PROGRAM_ABSTRACT_END