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GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star

Lam, Kristine W. F. and Csizmadia, Szilárd and Astudillo-Defru, Nicola and Bonfils, Xavier and Gandolfi, Davide and Padovan, Sebastiano and Esposito, Massimiliano and Hellier, Coel and Hirano, Teruyuki and Livingston, John and Murgas, Felipe and Smith, Alexis M. S. and Collins, Karen A. and Mathur, Savita and Garcia, Rafael A. and Howell, Steve B. and Santos, Nuno C. and Dai, Fei and Ricker, George R. and Vanderspek, Roland and Latham, David W. and Seager, Sara and Winn, Joshua N. and Jenkins, Jon M. and Albrecht, Simon and Almenara, Jose M. and Artigau, Étienne and Barragán, Oscar and Bouchy, François and Cabrera, Juan and Charbonneau, David and Chaturvedi, Priyanka and Chaushev, Alexander and Christiansen, Jessie L. and Cochran, William D. and De Meideiros, José R. and Delfosse, Xavier and Díaz, Rodrigo F. and Doyon, René and Eigmüller, Philipp and Figueira, Pedro and Forveille, Thierry and Fridlund, Malcolm and Gaisné, Guillaume and Goffo, Elisa and Georgieva, Iskra and Grziwa, Sascha and Guenther, Eike and Hatzes, Artie P. and Johnson, Marshall C. and Kabáth, Petr and Knudstrup, Emil and Korth, Judith and Lewin, Pablo and Lissauer, Jack J. and Lovis, Christophe and Luque, Rafael and Melo, Claudio and Morgan, Edward H. and Morris, Robert and Mayor, Michel and Narita, Norio and Osborne, Hannah L. M. and Palle, Enric and Pepe, Francesco and Persson, Carina M. and Quinn, Samuel N. and Rauer, Heike and Redfield, Seth and Schlieder, Joshua E. and Ségransan, Damien and Serrano, Luisa M. and Smith, Jeffrey C. and Šubjak, Ján and Twicken, Joseph D. and Udry, Stéphane and Van Eylen, Vincent and Vezie, Michael (2021) GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star. Science, 374 (6572). pp. 1271-1275. ISSN 0036-8075. doi:10.1126/science.aay3253.

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Ultrashort-period (USP) exoplanets have orbital periods shorter than 1 day. Precise masses and radii of USP exoplanets could provide constraints on their unknown formation and evolution processes. We report the detection and characterization of the USP planet GJ 367b using high-precision photometry and radial velocity observations. GJ 367b orbits a bright (V-band magnitude of 10.2), nearby, and red (M-type) dwarf star every 7.7 hours. GJ 367b has a radius of 0.718 ± 0.054 Earth-radii and a mass of 0.546 ± 0.078 Earth-masses, making it a sub-Earth planet. The corresponding bulk density is 8.106 ± 2.165 grams per cubic centimeter—close to that of iron. An interior structure model predicts that the planet has an iron core radius fraction of 86 ± 5%, similar to that of Mercury’s interior.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lam, Kristine W. F.0000-0002-9910-6088
Csizmadia, Szilárd0000-0001-6803-9698
Astudillo-Defru, Nicola0000-0002-8462-515X
Bonfils, Xavier0000-0001-9003-8894
Gandolfi, Davide0000-0001-8627-9628
Padovan, Sebastiano0000-0002-8652-3704
Esposito, Massimiliano0000-0002-6893-4534
Hellier, Coel0000-0002-3439-1439
Hirano, Teruyuki0000-0003-3618-7535
Livingston, John0000-0002-4881-3620
Murgas, Felipe0000-0001-9087-1245
Smith, Alexis M. S.0000-0002-2386-4341
Collins, Karen A.0000-0001-6588-9574
Mathur, Savita0000-0002-0129-0316
Garcia, Rafael A.0000-0002-8854-3776
Howell, Steve B.0000-0002-2532-2853
Santos, Nuno C.0000-0003-4422-2919
Dai, Fei0000-0002-8958-0683
Ricker, George R.0000-0003-2058-6662
Vanderspek, Roland0000-0001-6763-6562
Latham, David W.0000-0001-9911-7388
Seager, Sara0000-0002-6892-6948
Winn, Joshua N.0000-0002-4265-047X
Jenkins, Jon M.0000-0002-4715-9460
Albrecht, Simon0000-0003-1762-8235
Almenara, Jose M.0000-0003-3208-9815
Artigau, Étienne0000-0003-3506-5667
Barragán, Oscar0000-0003-0563-0493
Bouchy, François0000-0002-7613-393X
Cabrera, Juan0000-0001-6653-5487
Charbonneau, David0000-0002-9003-484X
Chaturvedi, Priyanka0000-0002-1887-1192
Chaushev, Alexander0000-0003-0061-5446
Christiansen, Jessie L.0000-0002-8035-4778
Cochran, William D.0000-0001-9662-3496
De Meideiros, José R.0000-0001-8218-1586
Delfosse, Xavier0000-0001-5099-7978
Díaz, Rodrigo F.0000-0001-9289-5160
Doyon, René0000-0001-5485-4675
Eigmüller, Philipp0000-0003-4096-0594
Figueira, Pedro0000-0001-8504-283X
Forveille, Thierry0000-0003-0536-4607
Fridlund, Malcolm0000-0002-0855-8426
Goffo, Elisa0000-0001-9670-961X
Georgieva, Iskra0000-0002-5056-1899
Grziwa, Sascha0000-0003-3370-4058
Guenther, Eike0000-0002-9130-6747
Hatzes, Artie P.0000-0002-3404-8358
Johnson, Marshall C.0000-0002-5099-8185
Kabáth, Petr0000-0002-1623-5352
Knudstrup, Emil0000-0001-7880-594X
Korth, Judith0000-0002-0076-6239
Lewin, Pablo0000-0003-0828-6368
Lissauer, Jack J.0000-0001-6513-1659
Lovis, Christophe0000-0001-7120-5837
Luque, Rafael0000-0002-4671-2957
Melo, Claudio0000-0002-6090-8446
Morgan, Edward H.0000-0003-1447-6344
Morris, Robert0000-0001-9303-3204
Mayor, Michel0000-0002-9352-5935
Narita, Norio0000-0001-8511-2981
Osborne, Hannah L. M.0000-0002-4143-4767
Palle, Enric0000-0003-0987-1593
Pepe, Francesco0000-0002-9815-773X
Persson, Carina M.0000-0003-1257-5146
Quinn, Samuel N.0000-0002-8964-8377
Rauer, Heike0000-0002-6510-1828
Redfield, Seth0000-0003-3786-3486
Schlieder, Joshua E.0000-0001-5347-7062
Ségransan, Damien0000-0003-2355-8034
Serrano, Luisa M.0000-0001-9211-3691
Smith, Jeffrey C.0000-0002-6148-7903
Šubjak, Ján0000-0002-5313-9722
Twicken, Joseph D.0000-0002-6778-7552
Udry, Stéphane0000-0001-7576-6236
Van Eylen, Vincent0000-0001-5542-8870
Vezie, Michael0000-0002-7930-1775
Additional Information:© 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. This is an article distributed under the terms of the Science Journals Default License. Received: 31 December 2020. Accepted: 12 October 2021. Published in print: 2 December 2021. We acknowledge use of observations from the LCOGT network. We made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC) ( Funding for DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. We acknowledge the use of public TESS Alert data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. This work was supported by the KESPRINT collaboration, an international consortium devoted to the characterization and research of exoplanets discovered with space-based missions. Some of the observations were made at Gemini South using the high-resolution imaging instrument Zorro, funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by S. B. Howell, N. Scott, E. P. Horch, and E. Quigley. Zorro was mounted on the Gemini 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); the National Research Council (Canada); Agencia Nacional de Investigacin y Desarrollo (Chile); Ministerio de Ciencia, Tecnologa e Innovacin (Argentina); Ministrio da Ciłncia, Tecnologia, Inovaes e Comunicaes (Brazil); and the Korea Astronomy and Space Science Institute (Republic of Korea). This is University of Texas Center for Planetary Systems Habitability Contribution no. 0041. K.W.F.L., Sz.Cs., M.E., S.G., A.P.H., and H.R. were supported by Deutsche Forschungsgemeinschaft grants PA525/18-1, PA525/19-1, PA525/20-1, HA3279/12-1, and RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. Sz.Cs. is supported by Deutsche Forschungsgemeinschaft Research Unit 2440, Matter Under Planetary Interior Conditions: High Pressure Planetary and Plasma Physics. T.H. was supported by JSPS KAKENHI grant no. JP19K14783, and N.N. was supported by JSPS KAKENHI grant nos. JP18H01265 and JP18H05439 and JST PRESTO grant no. JPMJPR1775. J.L. is supported by JSPS KAKENHI grant no. JP20K14518. R.A.G. acknowledges support from PLATO and GOLF CNES grants. P.K. acknowledges support from the MSMT grant LTT20015. S.M. acknowledges support by the Spanish Ministry of Science and Innovation with the Ramon y Cajal fellowship no. RYC-2015-17697 and grant no. PID2019-107187GB-I00. N.C.S. was supported by Fundaçao para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 - Programa Operacional Competitividade e Internacionalização grants UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113, and PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953. X.D. and G.G. acknowledge funding in the framework of the Investissements d’Avenir program (ANR-15-IDEX-02), Origin of Life project of the Université Grenoble-Alpes. J.R.D.M. acknowledges grants from CNPq, CAPES, and FAPERN Brazilian agencies. N.A.-D. acknowledges support from FONDECYT project 3180063. Resources for the production of the SPOC data products were provided by the NASA High-End Computing (HEC) program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. S.A. is supported by the Danish National Research Foundation (grant agreement no. DNRF106). D.G. and L.M.S. acknowledge financial support from the Cassa di Risparmio di Torino foundation under grant no. 2018.2323, “Gaseous or rocky? Unveiling the nature of small worlds.” Author contributions: K.W.F.L. contributed to the planet detection, transit light curve analysis, gyrochronology age estimate, and tidal evolution calculations and led the writing of the paper. Sz.Cs. performed the joint light curve and RV analysis using the Transit and Light Curve Modeller (TLCM). N.A.-D. and X.B. led the HARPS RV follow-up program and reduced and analyzed the RV data. D.G. performed the frequency analysis of the RV and activity indicators. F.D., O.B., A.P.H., and R.L. analyzed the RV data. S.P. determined the interior composition of the planet and modeled the precursor gaseous planet. M.E. performed the Rapid Eye Mount (REM) robotic telescope observations and analysis. M.E. and A.M.S.S. derived the light curve dilution factor. C.H., K.W.F.L., S.M., and R.A.G. determined the stellar rotation period using WASP data. S.B.H. analyzed the speckle imaging data. T.H. and M.F. performed the spectral analysis using SpecMatch-Emp, and T.H. derived the stellar parameters using an MCMC simulation. J.L. performed stellar characterization using isochrone fitting. F.M. performed the LCOGT and HARPS observations. K.A.C. coordinated the TESS SG1 working group. K.A.C. and P.L. analyzed the ground-based photometric observations. N.C.S. performed spectral characterization using ODUSSEAS. M.C.J. determined the Galactic space velocities of the star. K.W.F.L. and S.R. calculated the emission spectroscopy metric. J.K. performed transit-timing variation (TTV) analysis. J.C., P.E., and S.G. analyzed the light curve for planet detection. E.Gu. analyzed the activity indicators. G.R.R., R.V., D.W.L., S.S., J.N.W., and J.M.J. led and organized the TESS mission, including the observations, processing of the data, working groups coordination, target selection, and dissemination of the data products. E.H.M., M.V., and J.E.S. are members of the TESS POC who coordinated and scheduled the TESS science observations and conducted instrument planning. R.M., J.C.S., and J.D.T. are members of the SPOC who performed data calibration, light curve production, and transit planet detection. D.C., J.C., and S.N.Q. are members of the TSO who reviewed the data and performed planet candidate vetting. J.M.A., E.A., F.B., D.C., J.R.D.M., X.D., R.F.D., R.D., P.F., T.F., G.G., C.L., C.M., F.P., D.S., and S.U. are coinvestigators of the proposal, which provided the HARPS observations of the target and supported the interpretation of results. S.A., P.C., A.C., W.D.C., E.Go., I.G., P.K., E.K., J.J.L., N.N., H.L.M.O., E.P., C.M.P., H.R., L.M.S., J.Š., and V.V.E. are part of the KESPRINT consortium and contributed to the interpretation of the results. All authors contributed to the preparation of the paper. Data and materials availability: The TESS photometric observations are available at the Mikulski Archive for Space Telescopes (MAST) at under target name TOI 731.01. The raw HARPS spectroscopic data are available on the ESO Science Archive Facility under ESO program IDs 072.C-0488, 082.C-0718, 183.C-0437 (primary investigators: M. Mayor and X. Bonfils), and 1102.C-0339 (primary investigator: X. Bonfils). The ground-based photometry obtained by the LCO telescope and REM as well as the Gemini imaging data are available on the Exoplanet Follow-up Observing Program (ExoFOP) website under target name TOI 731.01. The raw Gemini data are available at under program ID GS-2021A-LP-105. The archival WASP data are available on the NASA Exoplanet Archive under object name GJ 367. Our reduced RVs and activity indices are listed in tables S1 and S2 and in machine-readable form in data S1 and S2. The TLCM is available at The authors declare no competing interests.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)PA525/18-1
Deutsche Forschungsgemeinschaft (DFG)PA525/19-1
Deutsche Forschungsgemeinschaft (DFG)PA525/20-1
Deutsche Forschungsgemeinschaft (DFG)HA3279/12-1
Deutsche Forschungsgemeinschaft (DFG)RA714/14-1
Deutsche Forschungsgemeinschaft (DFG)SPP 1992
Deutsche Forschungsgemeinschaft (DFG)2440
Japan Society for the Promotion of Science (JSPS)JP19K14783
Japan Society for the Promotion of Science (JSPS)JP18H01265
Japan Society for the Promotion of Science (JSPS)JP18H05439
Japan Science and Technology AgencyJPMJPR1775
Japan Society for the Promotion of Science (JSPS)JP20K14518
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Ministry of Education, Youth and Sports (Czech Republic)LTT20015
Ramón y Cajal ProgrammeRYC-2015-17697
Ministerio de Ciencia e Innovación (MCINN)PID2019-107187GB-I00
Fundaçao para a Ciência e a Tecnologia (FCT)UNSPECIFIED
Fundo Europeu de Desenvolvimento Regional (FEDER)UID/FIS/04434/2019
Fundo Europeu de Desenvolvimento Regional (FEDER)UIDB/04434/2020
Fundo Europeu de Desenvolvimento Regional (FEDER)UIDP/04434/2020
Fundo Europeu de Desenvolvimento Regional (FEDER)PTDC/FIS-AST/32113/2017
Fundo Europeu de Desenvolvimento Regional (FEDER)POCI-01-0145-FEDER-032113
Fundo Europeu de Desenvolvimento Regional (FEDER)PTDC/FIS-AST/28953/2017
Fundo Europeu de Desenvolvimento Regional (FEDER)POCI-01-0145-FEDER-028953
Agence Nationale pour la Recherche (ANR)ANR-15-IDEX-02
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)UNSPECIFIED
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)UNSPECIFIED
Fundação de Apoio à Pesquisa do RN (FAPERN)UNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3180063
Danish National Research FoundationDNRF106
Cassa di Risparmio di Torino Foundation2018.2323
Issue or Number:6572
Record Number:CaltechAUTHORS:20211203-174947953
Persistent URL:
Official Citation:GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star. Kristine W. F. Lam, et. al., Science, 374 (6572); DOI: 10.1126/science.aay3253
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112189
Deposited By: George Porter
Deposited On:03 Dec 2021 20:54
Last Modified:03 Dec 2021 20:54

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