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Low-Mass Stars and Their Very Low-Mass Companions

Presentation #339.04 in the session “Stars, Brown Dwarfs, and Binaries”.

Published onJan 11, 2021
Low-Mass Stars and Their Very Low-Mass Companions

Understanding the mechanics of stellar systems is imperative to comprehend how the constituents of the universe formed. Observations provide information and create a basis for theoretical models, refining our understanding of stellar systems. However, theoretical models have difficulty recreating some observed system architectures. Our sample consists of low-mass stellar/sub-stellar wide binary systems (> 1000 AU). Current theoretical models have difficulty keeping these systems bound on the order of gigayears due to their low gravitational binding energies. The spatial density of other objects in the galaxy should disrupt these binaries within gigayears, but they are not. To keep these systems bound, one possible solution is to add a tertiary or higher-order component(s), which would increase the system mass, thereby increasing the gravitational binding energy. We are investigating the multiplicity fraction around the lowest-mass systems using medium-resolution spectroscopy from the Near Infrared Echellete Spectrometer (NIRES) instrument on the Keck II 10-m telescope. We are analyzing new spectra of what have been previously determined to be common proper motion systems with similar distances. We are using radial velocities (RVs) measured from the NIRES spectra to determine the third velocity dimension for the kinematics of these systems. This will allow us t more confidently say these systems are gravitationally bound. We are also using these data to see if “spectral” binaries are present (blended light of closely bound systems), which would indicate the presence of triple or higher-order systems. This would help alleviate the tension between theory and observations regarding low mass wide binaries.

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