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A remnant planetary core in the hot-Neptune desert

Armstrong, David J. and Lopez, Théo A. and Adibekyan, Vardan and Booth, Richard A. and Bryant, Edward M. and Collins, Karen A. and Deleuil, Magali and Emsenhuber, Alexandre and Huang, Chelsea X. and King, George W. and Lillo-Box, Jorge and Lissauer, Jack J. and Matthews, Elisabeth 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 Delgado Mena, Elisa and Demangeon, Olivier D. S. and Dorn, Caroline and Dumusque, Xavier and Eigmüller, Philipp and Fausnaugh, Michael and Figueira, Pedro and Gan, Tianjun and Gandhi, Siddharth and Gill, Samuel and Gonzales, Erica J. and Goad, Michael R. and Günther, 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, Sara 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 and Villasenor, Jesus Noel and Vines, Jose I. and Zhan, Zhuchang (2020) A remnant planetary core in the hot-Neptune desert. Nature, 583 (7814). pp. 39-42. ISSN 0028-0836. doi:10.1038/s41586-020-2421-7.

[img] Image (JPEG) (Extended Data Fig. 1: Photometric data captured by the LCOGT network) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 2: HARPS activity correlation indicators) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 3: Tests on the HARPS residuals) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 4: Collected high-resolution imaging results from AstraLux/CAHA, NaCo/VLT, HRCam/SOAR and Zorro/Gemini (562 nm)) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 5: TOI-849 compared to field stars) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 6: Planet mass against time for three similar planets to TOI-849b in the Bern Population Synthesis models) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 1 List of stellar and planetary parameters used in the analysis) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 2 List of instrument parameters used in the analysis ) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 3 Stellar properties of TOI-849) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 4 HARPS radial velocities) - Supplemental Material
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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 large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune ‘desert’ (a region in mass–radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b, which is thought to have an unusually massive core, and recent discoveries such as LTT9779b and NGTS-4b, on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune’s but an anomalously large mass of 39.1^(+2.7)_(−2.6) Earth masses and a density of 5.2^(+0.7)_(−0.8) grams per cubic centimetre, similar to Earth’s. Interior-structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than 3.9^(+0.8)_(−0.9) per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation. Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.

Item Type:Article
Related URLs:
URLURL TypeDescription ReadCube access ItemTESS data ItemExofop-TESS archive ItemARES code (ARES v2)
Armstrong, David J.0000-0002-5080-4117
Booth, Richard A.0000-0002-0364-937X
Collins, Karen A.0000-0001-6588-9574
Emsenhuber, Alexandre0000-0002-8811-1914
Huang, Chelsea X.0000-0003-0918-7484
Lillo-Box, Jorge0000-0003-3742-1987
Lissauer, Jack J.0000-0001-6513-1659
Matthews, Elisabeth0000-0003-0593-1560
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
Demangeon, Olivier D. S.0000-0001-7918-0355
Dumusque, Xavier0000-0002-9332-2011
Eigmüller, Philipp0000-0003-4096-0594
Figueira, Pedro0000-0001-8504-283X
Gan, Tianjun0000-0002-4503-9705
Gonzales, Erica J.0000-0002-9329-2190
Günther, Maximilian N.0000-0002-3164-9086
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
Mordasini, Christoph0000-0002-1013-2811
Queloz, Didier0000-0002-3012-0316
Ricker, George R.0000-0003-2058-6662
Santerne, Alexandre0000-0002-3586-1316
Schlieder, Joshua E.0000-0001-5347-7062
Seager, Sara0000-0002-6892-6948
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
West, Richard G.0000-0001-6604-5533
Wilson, Paul A.0000-0002-7823-1090
Winn, Joshua N.0000-0002-4265-047X
Wheatley, Peter0000-0003-1452-2240
Zhan, Zhuchang0000-0002-4142-1800
Additional Information:© 2020 Springer Nature. Received 29 October 2019. Accepted 20 March 2020. Published 01 July 2020. This paper includes data collected by the TESS missions, which are publicly available from 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 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 and is based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme IDs 1102.C-0249 and P103.C-0449. Some of the observations presented in the paper used the High-Resolution Imaging instrument Zorro at Gemini South (programme ID GS-2019B-Q-111). Zorro was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by S.B.H., N. Scott, E. P. Horch and E. Quigley. D.J.A., D.V. and S.L.C. acknowledge support from the STFC via Ernest Rutherford Fellowships ST/R00384X/1, ST/P003850/1 and ST/R003726/1, respectively. M.B. and S.Gandhi acknowledge support from the STFC research grant ST/S000631/1. G.M.K. is supported by the Royal Society as a Royal Society University Research Fellow. F.M. acknowledges support from a 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 and 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. D.J.A.B. acknowledges support from the UK Space Agency. C.X.H. and M.N.G. acknowledge support from the Juan Carlos Torres Fellowship. This work was financed by FEDER (Fundo Europeu de Desenvolvimento Regional) funds through the COMPETE 2020 Operational Programme for Competitiveness and Internationalisation (POCI) and by Portuguese funds through FCT (Fundação para a Ciência e a Tecnologia) in the framework of projects UID/FIS/04434/2019; PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113; PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953. S.G.S., V.A., S.C.C.B. and O.D.S.D. acknowledge support from FCT through Investigador FCT contracts IF/00028/2014/CP1215/CT0002, IF/00650/2015/CP1273/CT0001, IF/01312/2014/CP1215/CT0004 and DL 57/2016/CP1364/CT0004. S.H. acknowledges support from fellowships PD/BD/128119/2016 funded by FCT (Portugal). Work by J.N.W. was partly funded by the Heising-Simons Foundation. C.A.W. acknowledges support from UK Science Technology and Facility Council grant ST/P000312/1. J.L.-B. and D. Barrado are funded by the Spanish State Research Agency (AEI) Projects ESP2017-87676-C5-1-R and MDM-2017-0737 Unidad de Excelencia María de Maeztu – Centro de Astrobiología (INTA-CSIC). J.S.J. acknowledges funding by Fondecyt through grant 1161218 and partial support from CATA-Basal (PB06, Conicyt). J.I.V. acknowledges support from CONICYT-PFCHA/Doctorado Nacional-21191829, Chile. The French group acknowledges financial support from the French Programme National de Planétologie (PNP, INSU). F.M. acknowledges support from the Royal Society Dorothy Hodgkin Fellowship. C.M. and A.E. acknowledge support from the Swiss National Science Foundation under grant BSSGI0_155816 “PlanetsInTime”. Parts of this work have been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation. Data availability: TESS data are publicly available at MAST ( The HARPS data used in this study are available within the paper or the Supplementary Information files and were collected under ESO programme ID 1102.C-0249. The NGTS (Data Tags 19249 and 19250), LCOGT (Data Tags 5106 and 5386) and specific detrended TESS light curve (Data Tag 19248) used in this work are available via the Exofop-TESS archive ( Code availability: The PASTIS code has been published previously. The latest version of the ARES code (ARES v2) is available at Author Contributions: D.J.A. is Principal Investigator of the NCORES HARPS programme, which measured the planet’s mass, and a member of the NGTS consortium; D.J.A. developed much of the text and main figures and coordinated all contributions. T.A.L. performed the joint PASTIS analysis. V.A., S.G.S. and N.C.S. performed stellar spectral analysis including chemical abundances. R.A.B. and F.M. provided text analysing potential formation scenarios. K.A.C. and E.L.N.J. coordinated the TFOP SG1 photometric follow-up of the system. K.I.C. and T.G. performed analysis of the LCOGT photometric follow-up of the system. A.E. and C.M. applied and analysed the Bern Population Synthesis Models. C.X.H. and L.S. developed and ran the MIT Quick Look Pipeline, which identified the candidate in the TESS data. G.W.K. performed the photoevaporation analysis. J.L.-B. obtained and analysed the Astralux data and synthesized all high-resolution imaging results. E.M. obtained the NaCo imaging data. H.O. contributed to the NCORES HARPS programme and the NGTS survey and helped to create the main figures. J.O., O.M., M.D., R.H., M. Lozovsky and C.D. performed the interior-structure calculations. D.V. performed analysis on the potential for tidal self-disruption. C.Z. obtained the SOAR data and provided text summarising the SOAR results. T.-G.T. obtained a further transit with the PEST telescope. J.J.L. contributed to the internal structure discussion. K.G.S. provided the independent check of stellar parameters. M.B. and S. Gandhi calculated estimates of the required telescope time for atmospheric characterization. D.R.A., M.M., E.M.B., C.A.W., J.S.J., J.I.V., J.S.A., D. Bayliss, C. Belardi, M.R.B., S.L.C., A.C., P.E., S. Gill, M.R.G., M.N.G., M. Lendl, J.M., D.P., D.Q., L.R., R.H.T. and R.G.W. contributed to the NGTS facility, in planning, management, data collection or detrending. D.J.A.B., S.H., D. Barrado, S.C.C.B., P.A.W., L.D.N., D. Bayliss, F.B., B.F.C., R.F.D., O.D.S.D., X.D., P.F., J.J., G.M.K., A.S., S.U., P.A.W., J.M.A. and A.O. contributed to the HARPS large programme under which the HARPS data were obtained. D.R.C., I.J.M.C., J.E.S. and S.B.H. contributed to the NaCo imaging data. C. Briceño, N.L. and A.W.M. contributed to the SOAR imaging data. K.D.C., M.F., J.S.J., E.L.N.J., G.R.R., P.R., S.S., E.T., R.V., J.N.W., J.N.V. and Z.Z. provided essential contributions to the TESS mission, which discovered the candidate. All authors read the manuscript and provided general comments. The authors declare no competing interests. Peer review information: Nature thanks Roman Baluev and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
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
Science and Technology Facilities Council (STFC)ST/S000631/1
NASA17-XRP17 2-0024
Dunlap Institute for Astronomy and AstrophysicsUNSPECIFIED
United Kingdom Space Agency (UKSA)UNSPECIFIED
MIT Kavli Institute for Astrophysics and Space ResearchUNSPECIFIED
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
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/FIS-AST/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
Agencia Estatal de InvestigaciónESP2017-87676-C5-1-R
Agencia Estatal de InvestigaciónMDM-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
Swiss National Science Foundation (SNSF)BSSGI0_155816
Issue or Number:7814
Record Number:CaltechAUTHORS:20200701-103607259
Persistent URL:
Official Citation:Armstrong, D.J., Lopez, T.A., Adibekyan, V. et al. A remnant planetary core in the hot-Neptune desert. Nature 583, 39–42 (2020).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104183
Deposited By: George Porter
Deposited On:01 Jul 2020 19:59
Last Modified:16 Nov 2021 18:29

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