Code of conduct

Upload instructions

What is exoplanet-talks.org?

News

The small size of M-dwarfs presents an opportunity for detecting small planets, smaller than planets orbiting larger host stars. In addition, their small size combined with their typical high proper motion allows to directly (as opposed to statistically) rule out false positive scenarios of transiting planet candidates. This validation makes them good targets for high precision radial velocities to measure the planet mass, and other follow-up studies including the characterization of the planet atmosphere or lack thereof. The typical small distance of M-dwarf stars that are bright enough for the above measurements means that Gaia time series astrometry will be sensitive to massive planets and brown dwarfs at wide orbits, with potential partial overlap with objects on orbits that radial velocities will be sensitive to. The M-dwarf opportunity is well aligned with the TESS Mission as it is surveying the entire sky with a redder band than Kepler's. This opportunity was already exemplified by the discovery of LHS 3844. We are now taking advantage of this opportunity to validate and/or confirm small transiting planets orbiting M-dwarfs identified as transiting by TESS. So far this project led to the discovery of GJ 1252 b (Shporer et al., accepted to ApJ Letters, arXiv:1912.05556), a 1.2 Earth radius and 2 Earth mass planet orbiting an M3-dwarf at 20.4 pc every 0.52 days, and LHS 1815 b (Gan et al., submitted to AJ), a 1.1 Earth radius planet orbiting an M1-dwarf at 29.9 pc every 3.81 days. LHS 1815 b was also identified as orbiting a star belonging to the galactic thick disk, making it a rare discovery. The broad theoretical goal of this project is to extend the theoretical and statistical understanding of transiting planets orbiting Sun-Like (FGK) stars, established through the Kepler Mission, to planets orbiting M-dwarfs. The attached plot shows that GJ 1252 b (in red) is one of the smallest planets with measured radius and mass, and in turn estimated composition.

Avi Shporer: The TESS M-dwarf opportunity