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

Fukui, Akihiko and Kimura, Tadahiro and Hirano, Teruyuki and Narita, Norio and Kodama, Takanori and Hori, Yasunori and Ikoma, Masahiro and Pallé, Enric and Murgas, Felipe and Parviainen, Hannu and Kawauchi, Kiyoe and Mori, Mayuko and Esparza-Borges, Emma and Bieryla, Allyson and Irwin, Jonathan and Safonov, Boris S. and Stassun, Keivan G. and Alvarez-Hernandez, Leticia and Béjar, Víctor J. S. and Casasayas-Barris, Núria and Chen, Guo and Crouzet, Nicolas and de Leon, Jerome P. and Isogai, Keisuke and Kagetani, Taiki and Klagyivik, Peter and Korth, Judith and Kurita, Seiya and Kusakabe, Nobuhiko and Livingston, John and Luque, Rafael and Madrigal-Aguado, Alberto and Morello, Giuseppe and Nishiumi, Taku and Orell-Miquel, Jaume and Oshagh, Mahmoudreza and Sánchez-Benavente, Manuel and Stangret, Monika and Terada, Yuka and Watanabe, Noriharu and Zou, Yujie and Tamura, Motohide and Kurokawa, Takashi and Kuzuhara, Masayuki and Nishikawa, Jun and Omiya, Masashi and Vievard, Sébastien and Ueda, Akitoshi and Latham, David W. and Quinn, Samuel N. and Strakhov, Ivan S. and Belinski, Alexandr A. and Jenkins, Jon M. and Ricker, George R. and Seager, Sara and Vanderspek, Roland and Winn, Joshua N. and Charbonneau, David and Ciardi, David R. and Collins, Karen A. and Doty, John P. and Bachelet, Etienne and Harbeck, Daniel (2022) TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf. Publications of the Astronomical Society of Japan, 74 (1). L1-L8. ISSN 0004-6264. doi:10.1093/pasj/psab106.

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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±0.08R⊕⁠, a mass of <19.5M⊕ (⁠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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Fukui, Akihiko0000-0002-4909-5763
Hirano, Teruyuki0000-0003-3618-7535
Narita, Norio0000-0001-8511-2981
Kodama, Takanori0000-0001-9032-5826
Hori, Yasunori0000-0003-4676-0251
Ikoma, Masahiro0000-0002-5658-5971
Pallé, Enric0000-0003-0987-1593
Murgas, Felipe0000-0001-9087-1245
Parviainen, Hannu0000-0001-5519-1391
Kawauchi, Kiyoe0000-0003-1205-5108
Mori, Mayuko0000-0003-1368-6593
Esparza-Borges, Emma0000-0002-2341-3233
Bieryla, Allyson0000-0001-6637-5401
Safonov, Boris S.0000-0003-1713-3208
Stassun, Keivan G.0000-0002-3481-9052
Béjar, Víctor J. S.0000-0002-5086-4232
Chen, Guo0000-0003-0740-5433
Crouzet, Nicolas0000-0001-7866-8738
de Leon, Jerome P.0000-0002-6424-3410
Isogai, Keisuke0000-0002-6480-3799
Kagetani, Taiki0000-0002-5331-6637
Korth, Judith0000-0002-0076-6239
Kusakabe, Nobuhiko0000-0001-9194-1268
Livingston, John0000-0002-4881-3620
Luque, Rafael0000-0002-4671-2957
Nishiumi, Taku0000-0003-1510-8981
Stangret, Monika0000-0002-1812-8024
Terada, Yuka0000-0003-2887-6381
Watanabe, Noriharu0000-0002-7522-8195
Zou, Yujie0000-0002-5609-4427
Tamura, Motohide0000-0002-6510-0681
Kuzuhara, Masayuki0000-0002-4677-9182
Nishikawa, Jun0000-0001-9326-8134
Omiya, Masashi0000-0002-5051-6027
Vievard, Sébastien0000-0003-4018-2569
Latham, David W.0000-0001-9911-7388
Quinn, Samuel N.0000-0002-8964-8377
Jenkins, Jon M.0000-0002-4715-9460
Ricker, George R.0000-0003-2058-6662
Seager, Sara0000-0002-6892-6948
Vanderspek, Roland0000-0001-6763-6562
Winn, Joshua N.0000-0002-4265-047X
Charbonneau, David0000-0002-9003-484X
Ciardi, David R.0000-0002-5741-3047
Collins, Karen A.0000-0001-6588-9574
Doty, John P.0000-0003-2996-8421
Bachelet, Etienne0000-0002-6578-5078
Harbeck, Daniel0000-0002-8590-007X
Additional Information:© The Author(s) 2021. Published by Oxford University Press on behalf of the Astronomical Society of Japan. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Received 2021 August 27; Accepted 2021 October 17; Published: 05 December 2021. Funding for the TESS mission is provided by NASA’s Science Mission Directorate. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS SPOC. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This paper includes data that are publicly available from the MAST. This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the NASA under the Exoplanet Exploration Program. This work makes use of observations from the LCO global telescope network. This paper is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center (ABC) and under financial supports by JSPS KAKENHI (JP18H05439) and JST PRESTO (JPMJPR1775), at FTN on Maui, HI, operated by the LCO, and observations made with the MuSCAT2 instrument, developed by ABC, at TCS operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. This paper is partially based on observations made at the CMO SAI MSU with the support by M.V. Lomonosov Moscow State University Program of Development. This work is partly supported by JSPS KAKENHI Grant Numbers 22000005, JP15H02063, JP17H04574, JP18H05439, JP18H05442, JP20K14518, Grant-in-Aid for JSPS Fellows Grant Number JP20J21872, JST PRESTO Grant Number JPMJPR1775, and the ABC of National Institutes of Natural Sciences (Grant Number AB031010). This work is partly financed by the Spanish Ministry of Economics and Competitiveness through grants PGC2018-098153-B-C31 and PID2019-109522GB-C53. A.A.B., B.S.S., and I.A.S. acknowledge the support of Ministry of Science and Higher Education of the Russian Federation under the grant 075-15-2020-780 (N13.1902.21.0039). N.C.B. and G.M. acknowledge the funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program under grant agreement No. 694513 and under the Marie Skłodowska-Curie grant agreement No. 895525, respectively. J.K. acknowledges the support of the Swedish National Space Agency (SNSA; DNR 2020-00104). R.L. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación, through project PID2019-109522GB-C52/AEI/10.13039/501100011033, and the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)JP18H05439
Japan Science and Technology AgencyJPMJPR1775
Japan Society for the Promotion of Science (JSPS)22000005
Japan Society for the Promotion of Science (JSPS)JP15H02063
Japan Society for the Promotion of Science (JSPS)JP17H04574
Japan Society for the Promotion of Science (JSPS)JP18H05439
Japan Society for the Promotion of Science (JSPS)JP18H05442
Japan Society for the Promotion of Science (JSPS)JP20K14518
Japan Society for the Promotion of Science (JSPS)JP20J21872
Japan Science and Technology AgencyJPMJPR1775
National Institutes of Natural Sciences of JapanAB031010
Ministerio de Economía, Industria y Competitividad (MINECO)PGC2018-098153-B-C31
Ministerio de Economía, Industria y Competitividad (MINECO)PID2019-109522GB-C53
Ministry of Science and Higher Education of the Russian Federation075-15-2020-780
Ministry of Science and Higher Education of the Russian FederationN13.1902.21.0039
European Research Council (ERC)694513
Marie Curie Fellowship895525
Swedish National Space AgencyDNR 2020-00104
Ministerio de Ciencia e Innovación (MCINN)PID2019-109522GB-C52/AEI/10.13039/501100011033
Severo OchoaSEV-2017-0709
Subject Keywords:techniques: photometric techniques: radial velocities planets and satellites: detection planets and satellites: individual planets and satellites: interiors
Issue or Number:1
Record Number:CaltechAUTHORS:20220131-860555000
Persistent URL:
Official Citation:Akihiko Fukui, Tadahiro Kimura, Teruyuki Hirano, Norio Narita, Takanori Kodama, Yasunori Hori, Masahiro Ikoma, Enric Pallé, Felipe Murgas, Hannu Parviainen, Kiyoe Kawauchi, Mayuko Mori, Emma Esparza-Borges, Allyson Bieryla, Jonathan Irwin, Boris S Safonov, Keivan G Stassun, Leticia Alvarez-Hernandez, Víctor J S Béjar, Núria Casasayas-Barris, Guo Chen, Nicolas Crouzet, Jerome P de Leon, Keisuke Isogai, Taiki Kagetani, Peter Klagyivik, Judith Korth, Seiya Kurita, Nobuhiko Kusakabe, John Livingston, Rafael Luque, Alberto Madrigal-Aguado, Giuseppe Morello, Taku Nishiumi, Jaume Orell-Miquel, Mahmoudreza Oshagh, Manuel Sánchez-Benavente, Monika Stangret, Yuka Terada, Noriharu Watanabe, Yujie Zou, Motohide Tamura, Takashi Kurokawa, Masayuki Kuzuhara, Jun Nishikawa, Masashi Omiya, Sébastien Vievard, Akitoshi Ueda, David W Latham, Samuel N Quinn, Ivan S Strakhov, Alexandr A Belinski, Jon M Jenkins, George R Ricker, Sara Seager, Roland Vanderspek, Joshua N Winn, David Charbonneau, David R Ciardi, Karen A Collins, John P Doty, Etienne Bachelet, Daniel Harbeck, TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf, Publications of the Astronomical Society of Japan, Volume 74, Issue 1, February 2022, Pages L1–L8,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113177
Deposited By: Tony Diaz
Deposited On:01 Feb 2022 18:15
Last Modified:08 Feb 2022 23:14

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