A Spectroscopic and Variability Census of All Mid-to-Late M-dwarfs within 15 Parsecs

Monday 2 July, 14:30

The only terrestrial exoplanets whose atmospheres will be studied in the next decade will be those that orbit M-dwarf stars. While the M-dwarf opportunity is widely recognized, it is less broadly appreciated that only the very closest and smallest stars will permit atmospheric studies with JWST and the ELTs. Within 15 parsecs, there are 456 stars with masses between 0.1 and 0.3 times the solar value. Our knowledge of these stars is woefully incomplete: Thirty percent of these stars have no published spectrum, and for an additional 40 percent the only available spectrum is of low resolution.

We are pursuing a multi-epoch, high-resolution spectroscopic survey of this nearly volume complete sample. In the northern hemisphere, we use the TRES instrument on the 1.5m telescope on Mt. Hopkins, Arizona; our two year survey will be complete at the time of Exoplanets II. In the southern hemisphere, we use the CHIRON instrument at the CTIO SMARTS 1.5m telescope. We measure systemic radial velocities, rotational broadening, and H-alpha equivalent widths. We have discovered eight new spectroscopic binaries, and will present preliminary orbits for these systems. We will also present new results from our photometric monitoring of these stars with the MEarth Observatory, providing rotation periods and constraints on large flares. Our census will ensure that every star within 15 parsecs and with a mass between 0.1-0.3 MSun is well characterized, and assist efforts to search every one of these for transiting planets whose atmospheres could be characterized.

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