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A remnant planetary core in the hot Neptunian desert

Armstrong, David J. and Lopez, Théo A. and Adibekyan, Vardan and Booth, Richard A. and Bryant, Edward M. and Collins, Karen A. and Emsenhuber, Alexandre and Huang, Chelsea X. and King, George W. and Lillo-Box, Jorge and Lissauer, Jack J. and Matthews, Elisabeth C. and Mousis, Olivier and Nielsen, Louise D. and Osborn, Hugh and Otegi, Jon and Santos, Nuno C. and Sousa, Sérgio G. and Stassun, Keivan G. and Veras, Dimitri and Ziegler, Carl and Acton, Jack S. and Almenara, Jose M. and Anderson, David R. and Barrado, David and Barros, Susana C. C. and Bayliss, Daniel and Belardi, Claudia and Bouchy, Francois and Briceño, César and Brogi, Matteo and Brown, David J. A. and Burleigh, Matthew R. and Casewell, Sarah L. and Chaushev, Alexander and Ciardi, David R. and Collins, Kevin I. and Colón, Knicole D. and Cooke, Benjamin F. and Crossfield, Ian J. M. and Díaz, Rodrigo F. and Deleuil, Magali and Delgado Mena, Elisa and Demangeon, Olivier D. S. and Dorn, Caroline and Dumusque, Xavier and Eigmuller, Philipp and Fausnaugh, Michael and Figueira, Pedro and Gan, Tianjun and Gandhi, Siddharth and Gill, Samuel and Goad, Michael R. and Guenther, Maximilian N. and Helled, Ravit and Hojjatpanah, Saeed and Howell, Steve B. and Jackman, James and Jenkins, James S. and Jenkins, Jon M. and Jensen, Eric L. N. and Kennedy, Grant M. and Latham, David W. and Law, Nicholas and Lendl, Monika and Lozovsky, Michael and Mann, Andrew W. and Moyano, Maximiliano and McCormac, James and Meru, Farzana and Mordasini, Christoph and Osborn, Ares and Pollacco, Don and Queloz, Didier and Raynard, Liam and Ricker, George R. and Rowden, Pamela and Santerne, Alexandre and Schlieder, Joshua E. and Seager, S. and Sha, Lizhou and Tan, Thiam-Guan and Tilbrook, Rosanna H. and Ting, Eric and Udry, Stéphane and Vanderspek, Roland and Watson, Christopher A. and West, Richard G. and Wilson, Paul A. and Winn, Joshua N. and Wheatley, Peter J. and Villasenor, Jesus Noel and Vines, Jose I. and Zhan, Zhuchang (2020) A remnant planetary core in the hot Neptunian desert. . (Unpublished)

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The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to major uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary pathways provide a new route to understanding planetary interiors. We present the discovery of TOI-849b, the remnant core of a giant planet, with a radius smaller than Neptune but an anomalously high mass M_p = 40.8^(+2.4)_(−2.5) M_⊕ and density of 5.5 ± 0.8 g cm⁻³, similar to the Earth. Interior structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than 3.9^(+0.8)_(−0.9)% of the total mass of the planet. TOI-849b transits a late G type star (T_(mag) = 11.5) with an orbital period of 18.4 hours, leading to an equilibrium temperature of 1800K. The planet's mass is larger than the theoretical threshold mass for runaway gas accretion. As such, the planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it avoided substantial gas accretion, perhaps through gap opening or late formation. Photoevaporation rates cannot provide the mass loss required to reduce a Jupiter-like gas giant, but can remove a few M⊕ hydrogen and helium envelope on timescales of several Gyr, implying that any remaining atmosphere is likely to be enriched by water or other volatiles from the planetary interior. TOI-849b represents a unique case where material from the primordial core is left over from formation and available to study.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Booth, Richard A.0000-0002-0364-937X
Collins, Karen A.0000-0001-6588-9574
Huang, Chelsea X.0000-0003-0918-7484
Lissauer, Jack J.0000-0001-6513-1659
Santos, Nuno C.0000-0003-4422-2919
Stassun, Keivan G.0000-0002-3481-9052
Veras, Dimitri0000-0001-8014-6162
Ziegler, Carl0000-0002-0619-7639
Barrado, David0000-0002-5971-9242
Bayliss, Daniel0000-0001-6023-1335
Briceño, César0000-0001-7124-4094
Brogi, Matteo0000-0002-7704-0153
Ciardi, David R.0000-0002-5741-3047
Collins, Kevin I.0000-0003-2781-3207
Colón, Knicole D.0000-0001-8020-7121
Crossfield, Ian J. M.0000-0002-1835-1891
Díaz, Rodrigo F.0000-0001-9289-5160
Dumusque, Xavier0000-0002-9332-2011
Figueira, Pedro0000-0001-8504-283X
Helled, Ravit0000-0001-5555-2652
Howell, Steve B.0000-0002-2532-2853
Jenkins, Jon M.0000-0002-4715-9460
Jensen, Eric L. N.0000-0002-4625-7333
Kennedy, Grant M.0000-0001-6831-7547
Latham, David W.0000-0001-9911-7388
Law, Nicholas0000-0001-9380-6457
Mann, Andrew W.0000-0003-3654-1602
Queloz, Didier0000-0002-3012-0316
Ricker, George R.0000-0003-2058-6662
Schlieder, Joshua E.0000-0001-5347-7062
Seager, S.0000-0002-6892-6948
Sha, Lizhou0000-0001-5401-8079
Tan, Thiam-Guan0000-0001-5603-6895
Ting, Eric0000-0002-8219-9505
Udry, Stéphane0000-0001-7576-6236
Vanderspek, Roland0000-0001-6763-6562
Winn, Joshua N.0000-0002-4265-047X
Wheatley, Peter J.0000-0003-1452-2240
Zhan, Zhuchang0000-0002-4142-1800
Additional Information:This paper includes data collected by the TESS missions, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). 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. 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 research has made use of the Exoplanet Follow-up Observation Program website and the NASA Exoplanet Archive, which are operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work makes use of observations from the LCOGT network. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 1102.C-0249. Based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program P103.C-0449. DJA, DV and SLC respectively acknowledge support from the STFC via Ernest Rutherford Fellowships (ST/R00384X/1), (ST/P003850/1) and (ST/R003726/1). GMK is supported by the Royal Society as a Royal Society University Research Fellow. FM. acknowledges support from the Royal Society Dorothy Hodgkin Fellowship. K.G.S. acknowledges partial support from NASA grant 17-XRP17 2-0024. C.Z. is supported by a Dunlap Fellowship at the Dunlap Institute for Astronomy & Astrophysics, funded through an endowment established by the Dunlap family and the University of Toronto. A.W.M was supported by NASA grant 80NSSC19K0097 to the University of North Carolina at Chapel Hill. DJAB acknowledges support from the UK Space Agency. CXH and MNG acknowledge support from the Juan Carlos Torres Fellowship. This work was financed by FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 - Operacional Programme for Competitiveness and Internationalisation (POCI), and by Portuguese funds through FCT - Fundação para a Ciência e a Tecnologia in the framework of the projects UID/FIS/04434/2019; PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113; PTDC/FISAST/28953/2017 & POCI-01-0145-FEDER-028953. SSou, VAdi, SCCBar, ODSD acknowledge support from FCT through Investigador FCT contracts nr. IF/00028/2014/CP1215/CT0002, IF/00650/2015/CP1273/CT0001, and IF/01312/2014/CP1215/CT0004, DL 57/2016/CP1364/CT0004. SHoj acknowledge support by the fellowships PD/BD/128119/2016 funded by FCT (Portugal). Work by JNW was partly funded by the Heising-Simons Foundation. CAW would like to acknowledge support from UK Science Technology and Facility Council grant ST/P000312/1. JLil and DBar are funded by the Spanish State Research Agency (AEI) Projects No.ESP2017-87676-C5-1-R and No. MDM-2017-0737 Unidad de Excelencia María de Maeztu-Centro de Astrobiología (INTA-CSIC). JSJ acknowledges funding by Fondecyt through grant 1161218 and partial support from CATA-Basal (PB06, Conicyt). JIV acknowledges support of CONICYT-PFCHA/Doctorado Nacional-21191829, Chile. The French group acknowledges financial support from the French Programme National de Planétologie (PNP, INSU). FM acknowledges support from the Royal Society Dorothy Hodgkin Fellowship. Author Contributions: DJArm is PI of the NCORES HARPS programme which measured the planet's mass, a member of the NGTS consortium, developed much of the text and main figures and coordinated all contributions. TLop performed the joint PASTIS analysis. VAdi, SSou, NSan performed stellar spectral analysis including chemical abundances. RBoo, FMer provided text analysing potential formation scenarios. KACol, EJen coordinated the TFOP SG1 photometric followup of the system. KICol, TGan, performed analysis of LCOGT photometric followup of the system. AEms, CMor performed and analyses the Bern Population Synthesis Models. CHua, LSha developed and ran the MIT Quick Look Pipeline which identified the candidate in the TESS data. GKin performed the photoevaporation analysis. JLil obtained and analyses the Astralux data, and synthesised all HR imaging results. EMat obtained the NaCo imaging data. HOsb contributed to the NCORES HARPS programme and the NGTS survey, and contributed to the main figures. JOte, OMou, MDel, RHel, MLoz, CDor performed interior structure calculations. DVer performed analysis on the potential for tidal self-disruption. CZie obtained the SOAR data and provided text summarising SOAR results. TGTan obtained a further transit with the PEST telescope. JLiss contributed to the internal structure discussion. KSta provided the independent check of stellar parameters. MBro, SGan calculated estimates of required telescope time for atmospheric characterisation. DRAnd, MMoy contributed to the maintenance and operation of the NGTS facility. EBry, CWat, JSJen, JIVin, JAct, DBay, CBel, MBur, SCas, ACha, PEig, SGil, MGoa, MGue, MLen, JMcC, DPol, DQue, LRay, RTil, RWes contributed to the NGTS facility, either in planning, management, data collection or detrending. DJABro, SHoj, DBar, SCCBar, PAW, LNie, DBay, FBou, BCoo, RDia, ODem, XDum, PFig, JJac, GKen, ASan, SUdr, PWil, JAlm contributed to the HARPS large programme under which HARPS data was obtained. DCia, ICro, JSch, SHow contributed to the NaCo imaging data. CBri, NLaw, AMan contributed to the SOAR imaging data. KDCol, MFau, JoJen, EJen, GRic, PRow, SSea, ETin, RVan, JWin, JNVil, ZZan provided essential contributions to the TESS mission which discovered the candidate. All authors read the manuscript and provided general comments. The authors declare that they have no competing financial interests.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Southern Observatory (ESO)P103.C-0449
Science and Technology Facilities Council (STFC)ST/R00384X/1
Science and Technology Facilities Council (STFC)ST/P003850/1
Science and Technology Facilities Council (STFC)ST/R003726/1
NASA17-XRP17 2-0024
Dunlap Institute for Astronomy and AstrophysicsUNSPECIFIED
United Kingdom Space Agency (UKSA)UNSPECIFIED
MIT Kavli Institute for Astrophysics and Space ResearchUNSPECIFIED
Fundo Europeu de Desenvolvimento RegionalUNSPECIFIED
Fundação para a Ciência e a Tecnologia (FCT)UID/FIS/04434/2019
Fundação para a Ciência e a Tecnologia (FCT)PTDC/FIS-AST/32113/2017
Fundação para a Ciência e a Tecnologia (FCT)POCI-01-0145-FEDER-032113
Fundação para a Ciência e a Tecnologia (FCT)PTDC/FISAST/28953/2017
Fundação para a Ciência e a Tecnologia (FCT)POCI-01-0145-FEDER-028953
Fundação para a Ciência e a Tecnologia (FCT)IF/00028/2014/CP1215/CT0002
Fundação para a Ciência e a Tecnologia (FCT)IF/00650/2015/CP1273/CT0001
Fundação para a Ciência e a Tecnologia (FCT)IF/01312/2014/CP1215/CT0004
Fundação para a Ciência e a Tecnologia (FCT)DL 57/2016/CP1364/CT0004
Fundação para a Ciência e a Tecnologia (FCT)PD/BD/128119/2016
Heising-Simons FoundationUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/P000312/1
Ministerio de Ciencia e Innovación (MCINN)ESP2017-87676-C5-1-R
Ministerio de Ciencia e Innovación (MCINN)MDM-2017-0737
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1161218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)21191829
Programme National de Planétologie (PNP)UNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Record Number:CaltechAUTHORS:20200611-113712339
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103848
Deposited By: George Porter
Deposited On:11 Jun 2020 21:33
Last Modified:11 Jun 2020 21:33

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