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HD 207897 b: A dense sub-Neptune transiting a nearby and bright K-type star

Heidari, N. and Boisse, I. and Orell-Miquel, J. and Hebrard, G. and Acuña, L. and Hara, N. C. and Lillo-Box, J. and Eastman, J. D. and Arnold, L. and Astudillo-Defru, N. and Adibekyan, V. and Bieryla, A. and Bonfils, X. and Bouchy, F. and Barclay, T. and Brasseur, C. E. and Borgniet, S. and Bourrier, V. and Buchhave, L. and Behmard, A. and Beard, C. and Batalha, N. M. and Courcol, B. and Cortés-Zuleta, P. and Collins, K. and Carmona, A. and Crossfield, I. J. M. and Chontos, A. and Delfosse, X. and Dalal, S. and Deleuil, M. and Demangeon, O. D. S. and Díaz, R. F. and Dumusque, X. and Daylan, T. and Dragomir, D. and Delgado Mena, E. and Dressing, C. and Dai, F. and Dalba, P. A. and Ehrenreich, D. and Forveille, T. and Fulton, B. and Fetherolf, T. and Gaisné, G. and Giacalone, S. and Riazi, N. and Hoyer, S. and Hobson, M. J. and Howard, A. W. and Huber, D. and Hill, M. L. and Hirsch, L. A. and Isaacson, H. and Jenkins, J. and Kane, S. R. and Kiefer, F. and Luque, R. and Latham, D. W. and Lubin, J. and Lopez, T. and Mousis, O. and Moutou, C. and Montagnier, G. and Mignon, L. and Mayo, A. and Močnik, T. and Murphy, J. M. A. and Palle, E. and Pepe, F. and Petigura, E. A. and Rey, J. and Ricker, G. and Robertson, P. and Roy, A. and Rubenzahl, R. A. and Rosenthal, L. J. and Santerne, A. and Santos, N. C. and Sousa, S. G. and Stassun, K. G. and Stalport, M. and Scarsdale, N. and Strøm, P. A. and Seager, S. and Segransan, D. and Tenenbaum, P. and Tronsgaard, R. and Udry, S. and Vanderspek, R. and Vakili, F. and Winn, J. N. and Weiss, L. M. (2022) HD 207897 b: A dense sub-Neptune transiting a nearby and bright K-type star. Astronomy and Astrophysics, 658 . Art. No. A176. ISSN 0004-6361. doi:10.1051/0004-6361/202141429.

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We present the discovery and characterization of a transiting sub-Neptune that orbits the nearby (28 pc) and bright (V = 8.37) K0V star HD 207897 (TOI-1611) with a 16.20-day period. This discovery is based on photometric measurements from the Transiting Exoplanet Survey Satellite mission and radial velocity (RV) observations from the SOPHIE, Automated Planet Finder, and HIRES high-precision spectrographs. We used EXOFASTv2 to model the parameters of the planet and its host star simultaneously, combining photometric and RV data to determine the planetary system parameters. We show that the planet has a radius of 2.50 ± 0.08 R_E and a mass of either 14.4 ± 1.6 M_E or 15.9 ± 1.6 M_E with nearly equal probability. The two solutions correspond to two possibilities for the stellar activity period. The density accordingly is either 5.1 ± 0.7 g cm⁻³ or 5.5_(−0.7)^(+0.8) g cm⁻³, making it one of the relatively rare dense sub-Neptunes. The existence of this dense planet at only 0.12 AU from its host star is unusual in the currently observed sub-Neptune (2 < R_E < 4) population. The most likely scenario is that this planet has migrated to its current position.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Boisse, I.0000-0001-8388-8399
Orell-Miquel, J.0000-0003-2066-8959
Lillo-Box, J.0000-0003-3742-1987
Astudillo-Defru, N.0000-0002-8462-515X
Bieryla, A.0000-0001-6637-5401
Bonfils, X.0000-0001-9003-8894
Bouchy, F.0000-0002-7613-393X
Barclay, T.0000-0001-7139-2724
Brasseur, C. E.0000-0002-9314-960X
Bourrier, V.0000-0002-9148-034X
Buchhave, L.0000-0003-1605-5666
Behmard, A.0000-0003-0012-9093
Batalha, N. M.0000-0002-7030-9519
Crossfield, I. J. M.0000-0002-1835-1891
Delfosse, X.0000-0001-5099-7978
Demangeon, O. D. S.0000-0001-7918-0355
Díaz, R. F.0000-0001-9289-5160
Dragomir, D.0000-0003-2313-467X
Dressing, C.0000-0001-8189-0233
Dai, F.0000-0002-8958-0683
Dalba, P. A.0000-0002-4297-5506
Ehrenreich, D.0000-0001-9704-5405
Forveille, T.0000-0003-0536-4607
Fulton, B.0000-0003-3504-5316
Giacalone, S.0000-0002-8965-3969
Hoyer, S.0000-0003-3477-2466
Howard, A. W.0000-0001-8638-0320
Huber, D.0000-0001-8832-4488
Hirsch, L. A.0000-0001-8058-7443
Isaacson, H.0000-0002-0531-1073
Jenkins, J.0000-0002-4715-9460
Kane, S. R.0000-0002-7084-0529
Luque, R.0000-0002-4671-2957
Latham, D. W.0000-0001-9911-7388
Lopez, T.0000-0001-6622-1250
Moutou, C.0000-0002-2842-3924
Palle, E.0000-0003-0987-1593
Petigura, E. A.0000-0003-0967-2893
Ricker, G.0000-0003-2058-6662
Robertson, P.0000-0003-0149-9678
Roy, A.0000-0001-8127-5775
Rubenzahl, R. A.0000-0003-3856-3143
Rosenthal, L. J.0000-0001-8391-5182
Santerne, A.0000-0002-3586-1316
Santos, N. C.0000-0003-4422-2919
Stassun, K. G.0000-0002-3481-9052
Scarsdale, N.0000-0003-3623-7280
Seager, S.0000-0002-6892-6948
Tronsgaard, R.0000-0003-1001-0707
Udry, S.0000-0001-7576-6236
Vanderspek, R.0000-0001-6763-6562
Winn, J. N.0000-0002-4265-047X
Weiss, L. M.0000-0002-3725-3058
Additional Information:© N. Heidari et al. 2022. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Received 29 May 2021; Accepted 8 September 2021; Published online 18 February 2022. We warmly thank the OHP staff for their support on the observations. X.B., I.B. and T.F. received funding from the French Programme National de Physique Stellaire (PNPS) and the Programme National de Planétologie (PNP) of CNRS (INSU). We also acknowledge the financial support of French embassy in Tehran. N.H. acknowledges F. Vakili for his constant academic and administrative support. N.H. warmly thanks Ph. Stee, J. L. Beuzit, E. T. Givenchy for all their help. N.H also thanks Jason D. Eastman and Michael Hippke who have written EXOFASTv2 and TLS package, respectively, for their guides. This publication makes use of The Data & Analysis Center for Exoplanets (DACE), which is a facility based at the University of Geneva (CH) dedicated to extrasolar planets data visualisation, exchange and analysis. DACE is a platform of the Swiss National Centre of Competence in Research (NCCR) PlanetS, federating the Swiss expertise in Exoplanet research. The DACE platform is available at J.L-B. acknowledges financial support received from “la Caixa” Foundation (ID 100010434) and from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 847648, with fellowship code LCF/BQ/PI20/11760023. This work has been carried out in the frame of the National Centre for Competence in Research “Planets” supported by the Swiss National Science Foundation (SNSF). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project SPICE DUNE, grant agreement No 947634). This work was supported by FCT – Fundação para a Ciência e Tecnologia (FCT) through national funds and by FEDER through COMPETE2020 – Programa OperacionalCompetitividade e Internacionalização by these grants: UID/FIS/04434/2019; UIDB/04434/2020; UIDP/04434/2020; PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113; PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953. V.A., E.D.M, N.C.S., and S.G.S. also acknowledge the support from FCT through Investigador FCT contracts nr. IF/00650/2015/CP1273/CT0001, IF/00849/2015/CP1273/CT0003, IF/00169/2012/CP0150/CT0002, and IF/00028/2014/CP1215/CT0002, respectively, and POPH/FSE (EC) by FEDER funding through the program “Programa Operacional de Factores de Competitividade – COMPETE”. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by FCT. A.C. et P.C. acknowledge funding from the French National Research Agency (ANR) under contract number ANR-18-CE31-0019 (SPlaSH). N.A.D. acknowledges the support of FONDECYT project 3180063. S.H. acknowledges CNES funding through the grant 837319. X.D. and G.G. acknowledge funding in the framework of the Investissements d’Avenir program (ANR-15-IDEX-02), through the funding of the ”Origin of Life” project of the Univ. Grenoble-Alpes. This work was supported by Fundação para a Ciência e a Tecnologia (FCT) and Fundo Europeu de Desenvolvimento Regional (FEDER) via COMPETE2020 through the research grants UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113, PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by FCT. 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. Funding for the TESS mission is provided by NASA’s Science Mission directorate. 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 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. This paper includes data collected by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). D.D acknowledges support from the TESS Guest Investigator Program grant 80NSSC19K1727 and NASA Exoplanet Research Program grant 18 − 2XRP182 − 0136. T.D acknowledges support from MIT’s Kavli Institute as a Kavli postdoctoral fellow. E.A.P. acknowledges the support of the Alfred P. Sloan Foundation. L.M.W. is supported by the Beatrice Watson Parrent Fellowship and NASA ADAP Grant 80NSSC19K0597. A.C. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1842402. D.H. acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC19K0379), and the National Science Foundation (AST-1717000). I.J.M.C. acknowledges support from the NSF through grant AST-1824644. P.D. acknowledges support from a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903811. A.B. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1745301. R.A.R. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1745301. C.D.D. acknowledges the support of the Hellman Family Faculty Fund, the Alfred P. Sloan Foundation, the David and Lucile Packard Foundation, and the National Aeronautics and Space Administration via the TESS Guest Investigator Program (80NSSC18K1583). J.M.A.M. is supported by the NSF Graduate Research Fellowship, grant No. DGE-1842400. J.M.A.M. and P.C. acknowledge the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant No. 1829740, the Brinson Foundation, and the Moore Foundation; their participation in the program has benefited this work. This paper is partially based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias.
Group:Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
Programme National de Physique Stellaire (PNPS)UNSPECIFIED
Programme National de Planetologie (PNP)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
French embassy (Tehran)UNSPECIFIED
La Caixa Foundation100010434
Marie Curie Fellowship847648
Marie Curie FellowshipLCF/BQ/PI20/11760023
Swiss National Science Foundation (SNSF)UNSPECIFIED
European Research Council (ERC)947634
Fundação para a Ciência e Tecnologia (FCT)UID/FIS/04434/2019
Fundação para a Ciência e Tecnologia (FCT)UIDB/04434/2020
Fundação para a Ciência e Tecnologia (FCT)UIDP/04434/2020
Fundação para a Ciência e Tecnologia (FCT)PTDC/FIS-AST/32113/2017
Fundação para a Ciência e Tecnologia (FCT)POCI-01-0145-FEDER-032113
Fundação para a Ciência e Tecnologia (FCT)PTDC/FIS-AST/28953/2017
Fundação para a Ciência e Tecnologia (FCT)POCI-01-0145-FEDER-028953
Fundação para a Ciência e Tecnologia (FCT)IF/00650/2015/CP1273/CT0001
Fundação para a Ciência e Tecnologia (FCT)IF/00849/2015/CP1273/CT0003
Fundação para a Ciência e Tecnologia (FCT)IF/00169/2012/CP0150/CT0002
Fundação para a Ciência e Tecnologia (FCT)IF/00028/2014/CP1215/CT0002
Fundação para a Ciência e Tecnologia (FCT)DL 57/2016/CP1364/CT0004
Agence Nationale pour la Recherche (ANR)ANR-18-CE31-0019
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3180063
Centre National d'Études Spatiales (CNES)837319
Agence Nationale pour la Recherche (ANR)ANR-15-IDEX-02
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
Fundação para a Ciência e Tecnologia (FCT)DL 57/2016/CP1364/CT0004
MIT Kavli Institute for Astrophysics and Space ResearchUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Beatrice Watson Parrent FellowshipUNSPECIFIED
NSF Graduate Research FellowshipDGE-1842402
NSF Astronomy and Astrophysics FellowshipAST-1903811
NSF Graduate Research FellowshipDGE-1745301
Hellman FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
NSF Graduate Research FellowshipDGE-1842400
Large Synoptic Survey Telescope CorporationUNSPECIFIED
Brinson FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:planets and satellites: detection – stars: activity – planets and satellites: individual: HD 207897 – planets and satellites: individual: TOI-1611 – planets and satellites: individual: TIC ID 264678534
Record Number:CaltechAUTHORS:20211130-215721917
Persistent URL:
Official Citation:HD 207897 b: A dense sub-Neptune transiting a nearby and bright K-type star. N. Heidari, I. Boisse, J. Orell-Miquel, G. Hébrard, L. Acuña, N. C. Hara, J. Lillo-Box, J. D. Eastman, L. Arnold, N. Astudillo-Defru, V. Adibekyan, A. Bieryla, X. Bonfils, F. Bouchy, T. Barclay, C. E. Brasseur, S. Borgniet, V. Bourrier, L. Buchhave, A. Behmard, C. Beard, N. M. Batalha, B. Courcol, P. Cortés-Zuleta, K. Collins, A. Carmona, I. J. M. Crossfield, A. Chontos, X. Delfosse, S. Dalal, M. Deleuil, O. D. S. Demangeon, R. F. Díaz, X. Dumusque, T. Daylan, D. Dragomir, E. Delgado Mena, C. Dressing, F. Dai, P. A. Dalba, D. Ehrenreich, T. Forveille, B. Fulton, T. Fetherolf, G. Gaisné, S. Giacalone, N. Riazi, S. Hoyer, M. J. Hobson, A. W. Howard, D. Huber, M. L. Hill, L. A. Hirsch, H. Isaacson, J. Jenkins, S. R. Kane, F. Kiefer, R. Luque, D. W. Latham, J. Lubin, T. Lopez, O. Mousis, C. Moutou, G. Montagnier, L. Mignon, A. Mayo, T. Močnik, J. M. A. Murphy, E. Palle, F. Pepe, E. A. Petigura, J. Rey, G. Ricker, P. Robertson, A. Roy, R. A. Rubenzahl, L. J. Rosenthal, A. Santerne, N. C. Santos, S. G. Sousa, K. G. Stassun, M. Stalport, N. Scarsdale, P. A. Strøm, S. Seager, D. Segransan, P. Tenenbaum, R. Tronsgaard, S. Udry, R. Vanderspek, F. Vakili, J. Winn and L. M. Weiss. A&A, 658 (2022) A176; DOI:
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ID Code:112106
Deposited By: George Porter
Deposited On:02 Dec 2021 20:37
Last Modified:03 Mar 2022 23:09

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