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Two temperate super-Earths transiting a nearby late-type M dwarf

Delrez, L. and Murray, C. A. and Pozuelos, F. J. and Narita, N. and Ducrot, E. and Timmermans, M. and Watanabe, N. and Burgasser, A. J. and Hirano, T. and Rackham, B. V. and Stassun, K. G. and Van Grootel, V. and Aganze, C. and Cointepas, M. and Howell, S. and Kaltenegger, L. and Niraula, P. and Sebastian, D. and Almenara, J. M. and Barkaoui, K. and Baycroft, T. A. and Bonfils, X. and Bouchy, F. and Burdanov, A. and Caldwell, D. A. and Charbonneau, D. and Ciardi, D. R. and Collins, K. A. and Daylan, T. and Demory, B.-O. and de Wit, J. and Dransfield, G. and Fajardo-Acosta, S. B. and Fausnaugh, M. and Fukui, A. and Furlan, E. and Garcia, L. J. and Gnilka, C. L. and Gómez Maqueo Chew, Y. and Gómez-Muñoz, M. A. and Günther, M. N. and Harakawa, H. and Heng, K. and Hooton, M. J. and Hori, Y. and Ikoma, M. and Jehin, E. and Jenkins, J. M. and Kagetani, T. and Kawauchi, K. and Kimura, T. and Kodama, T. and Kotani, T. and Krishnamurthy, V. and Kudo, T. and Kunovac, V. and Kusakabe, N. and Latham, D. W. and Littlefield, C. and McCormac, J. and Melis, C. and Mori, M. and Murgas, F. and Palle, E. and Pedersen, P. P. and Queloz, D. and Ricker, G. and Sabin, L. and Schanche, N. and Schroffenegger, U. and Seager, S. and Shiao, B. and Sohy, S. and Standing, M. R. and Tamura, M. and Theissen, C. A. and Thompson, S. J. and Triaud, A. H. M. J. and Vanderspek, R. and Vievard, S. and Wells, R. D. and Winn, J. N. and Zou, Y. and Zúñiga-Fernández, S. and Gillon, M. (2022) Two temperate super-Earths transiting a nearby late-type M dwarf. Astronomy and Astrophysics, 667 . Art. No. A59. ISSN 0004-6361. doi:10.1051/0004-6361/202244041.

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Context. In the age of JWST, temperate terrestrial exoplanets transiting nearby late-type M dwarfs provide unique opportunities for characterising their atmospheres, as well as searching for biosignature gases. In this context, the benchmark TRAPPIST-1 planetary system has garnered the interest of a broad scientific community. Aims. We report here the discovery and validation of two temperate super-Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively low-activity nearby (32 pc) M6V star. The inner planet, LP 890-9 b, was first detected by TESS (and identified as TOI-4306.01) based on four sectors of data. Intensive photometric monitoring of the system with the SPECULOOS Southern Observatory then led to the discovery of a second outer transiting planet, LP 890-9 c (also identified as SPECULOOS-2 c), previously undetected by TESS. The orbital period of this second planet was later confirmed by MuSCAT3 follow-up observations. Methods. We first inferred the properties of the host star by analyzing its Lick/Kast optical and IRTF/SpeX near-infrared spectra, as well as its broadband spectral energy distribution, and Gaia parallax. We then derived the properties of the two planets by modelling multi-colour transit photometry from TESS, SPECULOOS-South, MuSCAT3, ExTrA, TRAPPIST-South, and SAINT-EX. Archival imaging, Gemini-South/Zorro high-resolution imaging, and Subaru/IRD radial velocities also support our planetary interpretation. Results. With a mass of 0.118 ± 0.002 M_⊙, a radius of 0.1556 ± 0.0086 R_⊙, and an effective temperature of 2850 ± 75 K, LP 890-9 is the second-coolest star found to host planets, after TRAPPIST-1. The inner planet has an orbital period of 2.73 d, a radius of 1.320_(−0.027)^(+0.053) R_⊕, and receives an incident stellar flux of 4.09 ± 0.12 S_⊕. The outer planet has a similar size of 1.367_(−0.039)^(+0.055) R_⊕ and an orbital period of 8.46 d. With an incident stellar flux of 0.906 ± 0.026 S_⊕, it is located within the conservative habitable zone, very close to its inner limit (runaway greenhouse). Although the masses of the two planets remain to be measured, we estimated their potential for atmospheric characterisation via transmission spectroscopy using a mass-radius relationship and found that, after the TRAPPIST-1 planets, LP 890-9 c is the second-most favourable habitable-zone terrestrial planet known so far (assuming for this comparison a similar atmosphere for all planets). Conclusions. The discovery of this remarkable system offers another rare opportunity to study temperate terrestrial planets around our smallest and coolest neighbours.

Item Type:Article
Related URLs:
URLURL TypeDescription
Delrez, L.0000-0001-6108-4808
Murray, C. A.0000-0001-8504-5862
Pozuelos, F. J.0000-0003-1572-7707
Narita, N.0000-0001-8511-2981
Ducrot, E.0000-0002-7008-6888
Watanabe, N.0000-0002-7522-8195
Burgasser, A. J.0000-0002-6523-9536
Hirano, T.0000-0003-3618-7535
Rackham, B. V.0000-0002-3627-1676
Stassun, K. G.0000-0002-3481-9052
Van Grootel, V.0000-0003-2144-4316
Aganze, C.0000-0003-2094-9128
Howell, S.0000-0002-2532-2853
Kaltenegger, L.0000-0002-0436-1802
Niraula, P.0000-0002-8052-3893
Sebastian, D.0000-0002-2214-9258
Almenara, J. M.0000-0003-3208-9815
Barkaoui, K.0000-0003-1464-9276
Baycroft, T. A.0000-0002-3300-3449
Bonfils, X.0000-0001-9003-8894
Bouchy, F.0000-0002-7613-393X
Burdanov, A.0000-0001-9892-2406
Caldwell, D. A.0000-0003-1963-9616
Charbonneau, D.0000-0002-9003-484X
Ciardi, D. R.0000-0002-5741-3047
Collins, K. A.0000-0001-6588-9574
Daylan, T.0000-0002-6939-9211
Demory, B.-O.0000-0002-9355-5165
de Wit, J.0000-0003-2415-2191
Dransfield, G.0000-0002-3937-630X
Fajardo-Acosta, S. B.0000-0001-9309-0102
Fausnaugh, M.0000-0002-9113-7162
Fukui, A.0000-0002-4909-5763
Furlan, E.0000-0001-9800-6248
Garcia, L. J.0000-0002-4296-2246
Gnilka, C. L.0000-0003-2519-6161
Gómez Maqueo Chew, Y.0000-0002-7486-6726
Gómez-Muñoz, M. A.0000-0002-3938-4211
Günther, M. N.0000-0002-3164-9086
Harakawa, H.0000-0002-7972-0216
Heng, K.0000-0003-1907-5910
Hooton, M. J.0000-0003-0030-332X
Hori, Y.0000-0003-4676-0251
Ikoma, M.0000-0002-5658-5971
Jehin, E.0000-0001-8923-488X
Jenkins, J. M.0000-0002-4715-9460
Kagetani, T.0000-0002-5331-6637
Kawauchi, K.0000-0003-1205-5108
Kodama, T.0000-0001-9032-5826
Kotani, T.0000-0001-6181-3142
Krishnamurthy, V.0000-0003-2310-9415
Kudo, T.0000-0002-9294-1793
Kunovac, V.0000-0001-9419-3736
Kusakabe, N.0000-0001-9194-1268
Latham, D. W.0000-0001-9911-7388
Littlefield, C.0000-0001-7746-5795
McCormac, J.0000-0003-1631-4170
Melis, C.0000-0001-9834-7579
Mori, M.0000-0003-1368-6593
Murgas, F.0000-0001-9087-1245
Palle, E.0000-0003-0987-1593
Queloz, D.0000-0002-3012-0316
Ricker, G.0000-0003-2058-6662
Sabin, L.0000-0003-0242-0044
Schanche, N.0000-0002-9526-3780
Seager, S.0000-0002-6892-6948
Shiao, B.0000-0001-7842-3714
Standing, M. R.0000-0002-7608-8905
Tamura, M.0000-0002-6510-0681
Theissen, C. A.0000-0002-9807-5435
Thompson, S. J.0000-0002-8039-194X
Triaud, A. H. M. J.0000-0002-5510-8751
Vanderspek, R.0000-0001-6763-6562
Vievard, S.0000-0003-4018-2569
Wells, R. D.0000-0002-7240-8473
Winn, J. N.0000-0002-4265-047X
Zou, Y.0000-0002-5609-4427
Zúñiga-Fernández, S.0000-0002-9350-830X
Gillon, M.0000-0003-1462-7739
Additional Information: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 Science Processing Operations Center. 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 National Aeronautics and Space Administration under the Exoplanet Exploration Program. 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 collected by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). The research leading to these results has received funding from the European Research Council (ERC) under the FP/2007-2013 ERC grant agreement no 336480, and under the European Union’s Horizon 2020 research and innovation programme (grants agreements no 679030 & 803193/BEBOP); from an Action de Recherche Concertée (ARC) grant, financed by the Wallonia-Brussels Federation, from the Balzan Prize Foundation, from the BELSPO/BRAIN2.0 research program (PORTAL project), from the Science and Technology Facilities Council (STFC; grants no ST/S00193X/1, ST/00305/1, and ST/W000385/1), and from F.R.S-FNRS (Research Project ID T010920F). This work was also partially supported by a grant from the Simons Foundation (PI: Queloz, grant number 327127), as well as by the MERAC foundation (PI: Triaud). TRAPPIST is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant PDR T.0120.21, with the participation of the Swiss National Science Fundation (SNF). This work is partly supported by MEXT/JSPS KAKENHI Grant Numbers JP15H02063, JP17H04574, JP18H05439, JP18H05442, JP19K14783, JP21H00035, JP21K13975, JP21K20376, JP22000005, Grant-in-Aid for JSPS Fellows Grant Number JP20J21872, JST CREST Grant Number JPMJCR1761, the Astrobiology Center of National Institutes of Natural Sciences (NINS) (Grant Numbers AB031010, AB031014), and Social welfare juridical person SHIYUKAI (chairman MASAYUKI KAWASHIMA). This paper is based on data collected at the Subaru Telescope, which is located atop Maunakea and operated by the National Astronomical Observatory of Japan (NAOJ). We wish to recognise and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. This paper is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center and under financial supports by JSPS KAKENHI (JP18H05439) and JST PRESTO (JPMJPR1775), at Faulkes Telescope North on Maui, HI, operated by the Las Cumbres Observatory. Some of the observations in the paper made use of the High-Resolution Imaging instrument Zorro obtained under Gemini LLP Proposal Number: GN/S-2021A-LP-105. Zorro was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Zorro was mounted on the Gemini North (and/or South) telescope of the international Gemini Observatory, a program of NSF s OIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). We acknowledge funding from the European Research Council under the ERC Grant Agreement n. 3 37591-ExTrA. This work has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation. This work is based upon observations carried out at the Observatorio Astronómico Nacional at the Sierra de San Pedro Mártir (OAN-SPM), Baja California, México. We warmly thank the entire technical staff of the Observatorio Astronómico Nacional at San Pedro Mártir for their unfailing support to SAINT-EX operations. Research at Lick Observatory is partially supported by a generous gift from Google. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. M.G. and E.J. are F.R.S.-FNRS Senior Research Associates. V.V.G. is an F.R.S.-FNRS Research Associate. B.V.R. thanks the Heising-Simons Foundation for support. Y.G.M.C. acknowledges support from UNAM-PAPIIT IG-101321. B.-O.D. acknowledges support from the Swiss National Science Foundation (PP00P2-163967 and PP00P2-190080). M.N.G. acknowledges support from the European Space Agency (ESA) as an ESA Research Fellow. A.H.M.J.T acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no 803193/BEBOP), from the MERAC foundation, and from the Science and Technology Facilities Council (STFC; grants no ST/S00193X/1, ST/00305/1, and ST/W000385/1). E.D. acknowledges support from the innovation and research Horizon 2020 program in the context of the Marie Sklodowska-Curie subvention 945298. V.K. acknowledges support from NSF award AST2009343. This publication benefits from the support of the French Community of Belgium in the context of the FRIA Doctoral Grant awarded to M.T.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)336480
European Research Council (ERC)803193
Wallonia-Brussels FederationUNSPECIFIED
Balzan Prize FoundationUNSPECIFIED
Belgian Federal Science Policy Office (BELSPO)UNSPECIFIED
Science and Technology Facilities Council (STFC)ST/S00193X/1
Science and Technology Facilities Council (STFC)ST/00305/1
Science and Technology Facilities Council (STFC)ST/W000385/1
Fonds de la Recherche Scientifique (FNRS)T010920F
Simons Foundation327127
Fonds de la Recherche Scientifique (FNRS)T.0120.21
Swiss National Science Foundation (SNSF)PP00P2-163967
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)JP19K14783
Japan Society for the Promotion of Science (JSPS)JP21H00035
Japan Society for the Promotion of Science (JSPS)JP21K13975
Japan Society for the Promotion of Science (JSPS)JP21K20376
Japan Society for the Promotion of Science (JSPS)JP22000005
Japan Society for the Promotion of Science (JSPS)JP20J21872
Japan Science and Technology AgencyJPMJCR1761
National Institutes of Natural Sciences of JapanAB031010
National Institutes of Natural Sciences of JapanAB031014
Shiyukai Social Welfare Corp.UNSPECIFIED
Japan Science and Technology AgencyJPMJPR1775
Gemini PartnershipUNSPECIFIED
European Research Council (ERC)37591
Heising-Simons FoundationUNSPECIFIED
Universidad Nacional Autónoma de México (UNAM)IG-101321
Swiss National Science Foundation (SNSF)PP00P2-190080
European Space Agency (ESA)UNSPECIFIED
Marie Curie Fellowship945298
Record Number:CaltechAUTHORS:20221123-588237600.23
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ID Code:118028
Deposited By: Research Services Depository
Deposited On:07 Dec 2022 17:14
Last Modified:07 Dec 2022 17:20

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