TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf. (5th December 2021)

• Record Type: Journal Article
• 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;
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 74:Number 1(2022)
• Page Start: L1
• Page End: L8
• Publication Date: 2021-12-05
• Subjects: planets and satellites: detection -- planets and satellites: individual (TOI-2285b) -- planets and satellites: interiors -- techniques: photometric -- techniques: radial velocities; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psab106
• Languages: English
• ISSNs: 0004-6264

Abstract

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 H2 O layer under a hydrogen-rich atmosphere, then liquid water could exist on the surface of the H2 O 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.