11 research outputs found
TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf
We report the discovery of TO1-2285b, a sub-Neptune-sized planet transiting a nearby (42 pc) M dwarf with a period of 27.3 d. We identified the transit signal from the Transiting Exoplanet Survey Satellite photometric data, which we confirmed with ground-based photometric observations using the multiband imagers MuSCAT2 and MuSCAT3. Combining these data with other follow-up observations including high-resolution spectroscopy with the Tillinghast Reflector Echelle Spectrograph, high-resolution imaging with the SPeckle Polarimeter, and radial velocity (RV) measurements with the InfraRed Doppler instrument, we find that the planet has a radius of 1.74 +/- 0.08 R-circle plus, a mass of <19.5 M-circle plus + (95% c.I.), and an insolation flux of 1.54 +/- 0.14 times that of the Earth. Although the planet resides just outside the habitable zone for a rocky planet, if the planet harbors an H2O layer under a hydrogen-rich atmosphere, then liquid water could exist on the surface of the H2O layer depending on the planetary mass and water mass fraction. The bright host star in the near-infrared (K-s = 9.0) makes this planet an excellent target for further RV and atmospheric observations to improve our understanding of the composition, formation, and habitability of sub-Neptune-sized planets
TOI-1442 b and TOI-2445 b: two ultra-short period super-Earths around M dwarfs
Context. Exoplanets with orbital periods of less than one day are know as
Ultra-short period (USP) planets. They are relatively rare products of
planetary formation and evolution processes, but especially favourable to
current planet detection methods. At the time of writing, 120 USP planets have
already been confirmed. Aims. We aim to confirm the planetary nature of two new
transiting planet candidates announced by the NASA's Transiting Exoplanet
Survey Satellite (TESS), registered as TESS Objects of Interest (TOIs)
TOI-1442.01 and TOI-2445.01. Methods. We use the TESS data, ground-based
photometric light-curves and Subaru/IRD spectrograph radial velocity (RV)
measurements to validate both planetary candidates and to establish their
physical properties. Results. TOI-1442 b is a hot super-Earth with an orbital
period of , a radius of , equilibrium temperature of , and a mass at
3. TOI-2445 b is also a hot super-Earth/mini-Neptune with an orbital
period of , a radius of , equilibrium temperature of , and a mass at
3. Their physical properties align with current empirical trends and
formation theories of USP planets. More RV measurements will be useful to
constrain the planetary masses and mean densities, as well as the predicted
presence of outer planetary companions