The Occurrence Rate of Jupiter Analogs Around Low-Mass M Dwarfs

Low-mass M dwarfs are a key stellar population in the search for Earth analogs: due to their small sizes, they host the only terrestrial planets amenable to atmospheric study with JWST. However, the M-dwarf environment is quite different from that of our Sun. In particular, we note the outsized role Jupiter played in shaping our solar system, sculpting the dynamical environment in which the Earth formed and influencing the delivery of volatiles, the terrestrial refractory budget, and, potentially, Earth's overall habitability. Here, we investigate the occurrence rate of Jupiter-like planets around low-mass (0.1-0.3M⊙) M dwarfs. We monitor a volume-complete sample of 200 such stars, collecting four high-resolution spectra of each M dwarf over a span of six years. We use TRES on the 1.5 m telescope at the Fred Lawrence Whipple Observatory for sources with declinations δ > -15° and CHIRON on the Cerro Tololo Inter-American Observatory 1.5 m telescope for sources with δ < -15°. We do not detect any Jupiter-mass planets at Jupiter-like instellations, allowing us to place a 95%-confidence upper limit of 1.7% on the occurrence rate of Jupiter analogs. In contrast, surveys of Sun-like stars have found that giant planets are most common just beyond the snow line, at these Jupiter-like instellations. Our results indicate that architectures analogous to our solar system are rare around M dwarfs, with implications for the evolution and habitability of their terrestrial worlds.

This work was supported by a grant from the John Templeton Foundation. The lead author is supported in part by a Postgraduate Scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC).