TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf

February 2022 • 2022PASJ...74L...1F

Authors • Fukui, Akihiko • Kimura, Tadahiro • Hirano, Teruyuki • Narita, Norio • Kodama, Takanori • Hori, Yasunori • Ikoma, Masahiro • Pallé, Enric • Murgas, Felipe • Parviainen, Hannu • Kawauchi, Kiyoe • Mori, Mayuko • Esparza-Borges, Emma • Bieryla, Allyson • Irwin, Jonathan • Safonov, Boris S. • Stassun, Keivan G. • Alvarez-Hernandez, Leticia • Béjar, Víctor J. S. • Casasayas-Barris, Núria • Chen, Guo • Crouzet, Nicolas • de Leon, Jerome P. • Isogai, Keisuke • Kagetani, Taiki • Klagyivik, Peter • Korth, Judith • Kurita, Seiya • Kusakabe, Nobuhiko • Livingston, John • Luque, Rafael • Madrigal-Aguado, Alberto • Morello, Giuseppe • Nishiumi, Taku • Orell-Miquel, Jaume • Oshagh, Mahmoudreza • Sánchez-Benavente, Manuel • Stangret, Monika • Terada, Yuka • Watanabe, Noriharu • Zou, Yujie • Tamura, Motohide • Kurokawa, Takashi • Kuzuhara, Masayuki • Nishikawa, Jun • Omiya, Masashi • Vievard, Sébastien • Ueda, Akitoshi • Latham, David W. • Quinn, Samuel N. • Strakhov, Ivan S. • Belinski, Alexandr A. • Jenkins, Jon M. • Ricker, George R. • Seager, Sara • Vanderspek, Roland • Winn, Joshua N. • Charbonneau, David • Ciardi, David R. • Collins, Karen A. • Doty, John P. • Bachelet, Etienne • Harbeck, Daniel

Abstract • We report the discovery of TOI-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 $1.74 \pm 0.08\, R_\oplus$, a mass of $\lt \!\!19.5\,M_\oplus$ ($95\%$ c.l.), 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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022PASJ...74L...1F
• PDF http://academic.oup.com/pasj/pdf-lookup/doi/10.1093/pasj/psab106
• PREPRINT http://arxiv.org/abs/2110.10215
• DATA https://irsa.ipac.caltech.edu/bibdata/2022/F/2022PASJ...74L...1F.html
• ELECTR https://doi.org/10.1093%2Fpasj%2Fpsab106