The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation

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Haumea—one of the four known trans-Neptunian dwarf planets—is a very elongated and rapidly rotating body1,2,3. In contrast to other dwarf planets4,5,6, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system7, and the Centaur Chiron was later found to possess something similar to Chariklo’s rings8,9. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multi-chord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea’s equator and the orbit of its satellite Hi’iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea’s spin period—that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea’s largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates1,10,11. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected.

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  1. 1.

    et al. Photometric observations constraining the size, shape, and albedo of 2003 EL61, a rapidly rotating, Pluto-sized object in the Kuiper belt. Astrophys. J. 639, 1238–1251 (2006)

  2. 2.

    et al. Keck observatory laser guide star adaptive optics discovery and characterization of a satellite to the large Kuiper belt object 2003 EL61. Astrophys. J. 632, L45–L48 (2005)

  3. 3.

    , , & A collisional family of icy objects in the Kuiper belt. Nature 446, 294–296 (2007)

  4. 4.

    et al. A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation. Nature 478, 493–496 (2011)

  5. 5.

    et al. Albedo and atmospheric constraints of dwarf planet Makemake from a stellar occultation. Nature 491, 566–569 (2012)

  6. 6.

    et al. The Pluto system: initial results from its exploration by New Horizons. Science 350, aad1815 (2015)

  7. 7.

    et al. A ring system detected around the Centaur (10199) Chariklo. Nature 508, 72–75 (2014)

  8. 8.

    et al. Possible ring material around Centaur (2060) Chiron. Astron. Astrophys. 576, A18 (2015)

  9. 9.

    et al. 29 November 2011 stellar occultation by 2060 Chiron: symmetric jet-like features. Icarus 252, 271–276 (2015)

  10. 10.

    , & The size and shape of the oblong dwarf planet Haumea. Earth Moon Planets 111, 127–137 (2014)

  11. 11.

    et al. TNOs are cool: a survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of nine bright targets at 70–500 μm. Astron. Astrophys. 555, A15 (2013)

  12. 12.

    , & The rings of Uranus. Nature 267, 328–330 (1977)

  13. 13.

    et al. Occultation detection of a Neptunian ring-like arc. Nature 319, 636–640 (1986)

  14. 14.

    et al. Near-infrared spatially resolved spectroscopy of (136108) Haumea’s multiple system. Astron. Astrophys. 593, A19 (2016)

  15. 15.

    , & The diverse solar phase curves of distant icy bodies. I. Photometric observations of 18 trans-Neptunian objects, 7 Centaurs, and Nereid. Astron. J. 133, 26–43 (2007)

  16. 16.

    et al. “TNOs are cool”: a survey of the trans-Neptunian region. II. The thermal lightcurve of (136108) Haumea. Astron. Astrophys. 518, L147 (2010)

  17. 17.

    , & High-precision photometry of extreme KBO 2003 EL61. Astron. J. 135, 1749–1756 (2008)

  18. 18.

    et al. Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs. Astron. Astrophys. 522, A93 (2010)

  19. 19.

    , , & in Asteroids II (eds et al.) 416–441 (Univ. Arizona Press, 1989)

  20. 20.

    & Orbits and masses of the satellites of the dwarf planet Haumea (2003 EL61). Astron. J. 137, 4766–4776 (2009)

  21. 21.

    Density of asteroids. Planet. Space Sci. 73, 98–118 (2012)

  22. 22.

    et al. Physical properties of trans-Neptunian binaries (120347) Salacia-Actaea and (42355) Typhon-Echidna. Icarus 219, 676–688 (2012)

  23. 23.

    Ellipsoidal Figures of Equilibrium (Dover, 1987)

  24. 24.

    Spin limits of Solar System bodies: from the small fast-rotators to 2003 EL61. Icarus 187, 500–509 (2007)

  25. 25.

    Equilibrium configurations of solid cohesionless bodies. Icarus 154, 432–448 (2001)

  26. 26.

    ., ., & Equilibrium figures of dwarf planets. In AAS/Division of Planetary Sciences Meeting Vol. 48, abstr. 120.15 (American Astronomical Society, 2016)

  27. 27.

    et al. Orbit determination of trans-Neptunian objects and Centaurs for the prediction of stellar occultations. Astron. Astrophys. 584, A96 (2015)

  28. 28.

    et al. A mid-term astrometric and photometric study of trans-Neptunian object (90482) Orcus. Astron. Astrophys. 525, A31 (2011)

  29. 29.

    , , , & Hot Stuff for One Year (HSOY). A 583 million star proper motion catalogue derived from Gaia DR1 and PPMXL. Astron. Astrophys. 600, L4 (2017)

  30. 30.

    Least-squares frequency analysis of unequally spaced data. Astrophys. Space Sci. 39, 447–462 (1976)

  31. 31.

    , , & & Merlin, F. High-contrast observations of (136108) Haumea. A crystalline water-ice multiple system. Astron. Astrophys. 528, A105 (2011)

  32. 32.

    et al. Results from the 2014 November 15th multi-chord stellar occultation by the TNO (229762) 2007 UK126. Astron. J. 152, 156 (2016)

  33. 33.

    et al. Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo. Astron. Astrophys. 568, A79 (2014)

  34. 34.

    , , , & Physical properties of Centaur (54598) Bienor from photometry. Mon. Not. R. Astron. Soc. 466, 4147–4158 (2017)

  35. 35.

    , , & Characterisation of candidate members of (136108) Haumea’s family. Astron. Astrophys. 511, A72 (2010)

  36. 36.

    Comprehensive photometry of the rings and 16 satellites of Uranus with the Hubble Space Telescope. Icarus 151, 51–68 (2001)

  37. 37.

    et al. Saturn’s rings at true opposition. Publ. Astron. Soc. Pacif. 119, 623–642 (2007)

  38. 38.

    et al. Formation of Centaurs’ rings through their partial tidal disruption during planetary encounters. Astrophys. J. 828, L8 (2016)

  39. 39.

    , , & Assessment of different formation scenarios for the ring system of (10199) Chariklo. Astron. Astrophys. 602, A27 (2017)

  40. 40.

    , , & The origin of planetary ring systems. Preprint at (2017)

  41. 41.

    & On the mass and origin of Chariklo’s rings. Astrophys. J. 821, 18 (2016)

  42. 42.

    & The creation of Haumea’s collisional family. Astrophys. J. 700, 1242–1246 (2009)

  43. 43.

    Why are dense planetary rings only found between 8 and 20 AU? Astrophys. J. 801, L33 (2015)

  44. 44.

    et al. The short rotation period of Hi’iaka, Haumea’s largest satellite. Astron. J. 152, 195 (2016)

  45. 45.

    Ellipsoidal geometry in asteroid thermal models: the standard radiometric model. Icarus 64, 53–63 (1985)

  46. 46.

    et al. The surface of (136108) Haumea (2003 EL61), the largest carbon depleted object in the trans-neptunian belt. Astron. Astrophys. 496, 547–556 (2009)

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These results were based on observations made with the 2-m telescope at Wendelstein Observatory, which is operated by the Universitäts-Sternwarte München, the 1.8-m telescope at Asiago Observatory, operated by Padova Observatory, a member of the National Institute for Astrophysics, the 1.3-m telescope at Skalnate Pleso Observatory, operated by the Astronomical Institute of the Slovak Academy of Science, the 1-m telescope at Konkoly observatory, operated by Astrophysical Institute of the Hungarian Academy of Sciences, the 0.65-m telescope at Ondrejov Observatory, operated by the Astronomical Institute of the Czech Academy of Sciences, the 1.5-m telescope at Sierra Nevada Observatory, operated by the Instituto de Astrofisica de Andalucia-CSIC, the 1.23-m telescope at Calar Alto Observatory, jointly operated by the Max Planck Institute für Astronomie and the IAA-CSIC, the Roque de los Muchachos Observatory 2-m Liverpool telescope, operated by the Astrophysics Research Institute of Liverpool John Moores University, the Roque de los Muchachos Observatory 2.5-m NOT telescope, operated by the Nordic Optical Telescope Scientific Association, the 1-m telescope at Pic du Midi Observatory, operated by the Observatoire Midi Pyrénées, and the La Hita 0.77-m telescope, which is jointly operated by Astrohita and the IAA-CSIC. J.L.O. acknowledges funding from Spanish and Andalusian grants MINECO AYA-2014-56637-C2-1-P and J. A. 2012-FQM1776 as well as FEDER funds. Part of the research leading to these results received funding from the European Union’s Horizon 2020 Research and Innovation Programme, under grant agreement no. 687378. B.S. acknowledges support from the French grants ‘Beyond Neptune’ ANR-08-BLAN-0177 and ‘Beyond Neptune II’ ANR-11-IS56-0002. Part of the research leading to these results has received funding from the European Research Council under the European Community’s H2020 (2014-2020/ERC grant agreement no. 669416 ‘Lucky Star’). A.P. and R.S. have been supported by the grant LP2012-31 of the Hungarian Academy of Sciences. All of the Hungarian contributors acknowledge the partial support from K-125015 grant of the National Research, Development and Innovation Office (NKFIH). G.B.-R., F.B.-R., F.L.R., R.V.-M., J.I.B.C., M.A., A.R.G.-J. and B.E.M. acknowledge support from CAPES, CNPq and FAPERJ. J.C.G. acknowledges funding from AYA2015-63939-C2-2-P and from the Generalitat Valenciana PROMETEOII/2014/057. K.H. and P.P. were supported by the project RVO:67985815. The Astronomical Observatory of the Autonomous Region of the Aosta Valley acknowledges a Shoemaker NEO Grant 2013 from The Planetary Society. We acknowledge funds from a 2016 ‘Research and Education’ grant from Fondazione CRT. We also acknowledge the Slovakian project ITMS no. 26220120029.

Author information


  1. Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía S/N, 18008-Granada, Spain

    • J. L. Ortiz
    • , P. Santos-Sanz
    • , N. Morales
    • , R. Duffard
    •  & E. Fernández-Valenzuela
  2. LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Universités Paris 06, Universités Paris Diderot, Sorbonne Paris Cité, France

    • B. Sicardy
    • , D. Bérard
    • , J. Lecacheux
    • , J. Desmars
    • , E. Meza
    •  & F. Roques
  3. Observatório Nacional/MCTIC, Rua General José Cristino 77, Rio de Janeiro CEP 20921-400, Brazil

    • G. Benedetti-Rossi
    • , F. Braga-Ribas
    • , R. Vieira-Martins
    • , J. I. B. Camargo
    • , A. Alvarez-Candal
    •  & B. E. Morgado
  4. Federal University of Technology-Paraná (UTFPR/DAFIS), Rua Sete de Setembro 3165, CEP 80230-901 Curitiba, Brazil

    • F. Braga-Ribas
    •  & F. L. Rommel
  5. Universitäts-Sternwarte München, München, Scheiner Straße 1, D-81679 München, Germany

    • U. Hopp
    •  & C. Ries
  6. Max-Planck-Institut für Extraterrestrische Physik, D-85741 Garching, Germany

    • U. Hopp
    • , T. G. Mueller
    •  & V. Alí-Lagoa
  7. Dipartimento di Fisica e Astronomia, ‘G. Galilei’, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, I-35122 Padova, Italy

    • V. Nascimbeni
    •  & V. Granata
  8. INAF—Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, I-35122 Padova, Italy

    • V. Nascimbeni
    •  & V. Granata
  9. Dipartimento di Fisica, University of Padova, via Marzolo 8, 35131 Padova, Italy

    • F. Marzari
  10. Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege 15-17, H-1121 Budapest, Hungary

    • A. Pál
    • , C. Kiss
    • , R. Szakáts
    • , A. Takácsné Farkas
    • , E. Varga-Verebélyi
    •  & G. Marton
  11. Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranská Lomnica, Slovakia

    • T. Pribulla
    •  & R. Komžík
  12. Astronomical Institute, Academy of Sciences of the Czech Republic, Fričova 298, 251 65 Ondřejov Czech Republic

    • K. Hornoch
    •  & P. Pravec
  13. Astronomical Observatory San Marcello Pistoiese CARA Project, San Marcello Pistoiese, Pistoia, Italy

    • P. Bacci
    • , M. Maestripieri
    • , L. Nerli
    •  & L. Mazzei
  14. Osservatorio astronomico di Tavolaia, Santa Maria a Monte, Italy

    • M. Bachini
    •  & G. Succi
  15. Lajatico Astronomical Centre, Via Mulini a Vento 9 Orciatico, cap 56030 Lajatico, Italy

    • M. Bachini
    • , F. Martinelli
    •  & G. Succi
  16. Osservatorio Astronomico di Monte Agliale, Via Cune Motrone, I-55023 Borgo a Mozzano, Italy

    • F. Ciabattari
  17. Črni Vrh Observatory, Predgriže 29A, 5274 Črni Vrh nad Idrijo, Slovenia

    • H. Mikuz
  18. Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA), Lignan 39, 11020 Nus, Italy

    • A. Carbognani
    •  & J. M. Christille
  19. Bayerische Volkssternwarte München, Rosenheimer Straße 145h, D-81671 München, Germany

    • B. Gaehrken
  20. German Aerospace Center (DLR), Institute of Planetary Research, Rutherfordstraße 2, 12489 Berlin, Germany

    • S. Mottola
    •  & S. Hellmich
  21. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, PO Box 99, E-03080 Alicante, Spain

    • A. Campo Bagatin
  22. Instituto Universitario de Física Aplicada a las Ciencias y la Tecnología, Universidad de Alicante, PO Box 99, E-03080 Alicante, Spain

    • A. Campo Bagatin
  23. University of Zagreb, Faculty of Electrical Engineering and Computing, Department of Applied Physics, Unska 3, 10000 Zagreb, Croatia

    • S. Cikota
  24. Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia

    • S. Cikota
  25. European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany

    • A. Cikota
  26. IMCCE/Observatoire de Paris, 77 Avenue Denfert Rochereau, 75014 Paris, France

    • R. Vieira-Martins
    • , F. Colas
    • , F. Vachier
    •  & J. Berthier
  27. Laboratório Interinstitucional de e-Astronomia-LIneA, Rua General José Cristino 77, Rio de Janeiro CEP 20921-400, Brazil

    • R. Vieira-Martins
    •  & J. I. B. Camargo
  28. Observatório do Valongo/UFRJ, Ladeira Pedro Antônio 43, Rio de Janeiro CEP 20080-090, Brazil

    • R. Vieira-Martins
    • , M. Assafin
    •  & A. R. Gomes-Junior
  29. Observatoire de Genève, CH1290 Sauverny, Switzerland

    • R. Behrend
  30. International Occultation Timing Association—European Section (IOTA-ES) Bartold-Knausstraße 8, D-30459 Hannover, Germany

    • W. Beisker
  31. Facultad de Ciencias Experimentales, Universidad de Huelva, Avenida de las Fuerzas Armadas, 21071 Huelva, Spain

    • J. M. Madiedo
  32. Ege University, Faculty of Science, Department of Physics, 35100 Izmir, Turkey

    • O. Unsalan
  33. University of Adiyaman, Department of Physics, 02040 Adiyaman, Turkey

    • E. Sonbas
    •  & N. Karaman
  34. TUBITAK National Observatory (TUG), Akdeniz University Campus, 07058 Antalya, Turkey

    • O. Erece
    • , D. T. Koseoglu
    •  & T. Ozisik
  35. Ondokuz Mayis University Observatory, Space Research Center, 55200 Kurupelit, Turkey

    • S. Kalkan
  36. Atatürk University, Science Faculty, Department of Physics, 25240 Erzurum, Turkey

    • Y. Guney
  37. Atatürk University, Astrophysics Research and Application Center (ATASAM), 25240 Erzurum, Turkey

    • M. S. Niaei
    • , O. Satir
    •  & C. Yesilyaprak
  38. Atatürk University, Science Faculty, Department of Astronomy and Astrophysics, 25240 Erzurum, Turkey

    • C. Yesilyaprak
  39. Canakkale Onsekiz Mart University, Astrophysics Research Center (ARC) and Ulupınar Observatory (UPO), Canakkale, Turkey

    • C. Puskullu
    • , A. Kabas
    •  & O. Demircan
  40. Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, GR-15236 Penteli, Greece

    • J. Alikakos
    •  & V. Charmandaris
  41. Department of Physics, University of Crete, GR-71003 Heraklion, Greece

    • V. Charmandaris
  42. INAF—Catania Astrophysical Observatory, Via Santa Sofia 78, I-95123 Catania, Italy

    • G. Leto
  43. Michael Adrian Observatorium, Astronomie Stiftung Trebur, Fichtenstraße 7, 65468 Trebur, Germany

    • J. Ohlert
  44. University of Applied Sciences, Technische Hochschule Mittelhessen, Wilhelm-Leuschner-Straße 13, D-61169 Friedberg, Germany

    • J. Ohlert
  45. Astronomical Observatory Institute, Faculty of Physics, A. Mickiewicz University, Słoneczna 36, 60-286 Poznań, Poland

    • A. Marciniak
    • , P. Bartczak
    • , T. Santana-Ros
    • , M. Butkiewicz-Bąk
    •  & G. Dudziński
  46. Section of Astrophysics, Astronomy and Mechanics, Department of Physics, National and Kapodistrian University of Athens, GR-15784 Athens, Greece

    • K. Gazeas
    •  & L. Tzouganatos
  47. Nunki Observatory, Skiathos Island 37002, Greece

    • N. Paschalis
  48. Ellinogermaniki Agogi Observatory, Dimitriou Panagea street, GR-15351 Athens, Greece

    • V. Tsamis
  49. Departamento de Física Aplicada I, Escuela de Ingeniería de Bilbao, Universidad del País Vasco UPV/EHU, Plaza Torres Quevedo 1, 48013 Bilbao, Spain

    • A. Sánchez-Lavega
    • , S. Pérez-Hoyos
    •  & R. Hueso
  50. Observatori Astronòmic de la Universitat de València, Catedrático José Beltrán, 2, 46980 Paterna, Spain

    • J. C. Guirado
    •  & V. Peris
  51. Departament d’Astronomia i Astrofísica, Universitat de València, Calle Dr Moliner 50, E-46100 Burjassot, Spain

    • J. C. Guirado
  52. Centro de Estudios de Física del Cosmos de Aragón, Plaza de San Juan 1, 2ª planta, 44001 Teruel, Spain

    • R. Iglesias-Marzoa
  53. Departamento de Astrofísica, Universidad de La Laguna, Avenida Astrofísico Fco Sánchez, 38200 La Laguna, Spain

    • R. Iglesias-Marzoa


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J.L.O. planned the campaign, analysed data for the prediction, made the prediction, participated in the observations, obtained and analysed data, interpreted the data and wrote the paper. P.S.-S. helped to plan the campaign, analysed data, helped to interpret the data and helped to write the paper. B.S. helped to plan the campaign, analysed data, interpreted data, and wrote part of the paper. G.B.-R. and D.B. helped to plan the campaign, participated in the observations, and analysed and interpreted data. All other authors participated in the planning of the campaign and/or the observations and/or the interpretations. All authors were given the opportunity to review the results and comment on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to J. L. Ortiz.

Reviewer Information Nature thanks A. Sickafoose and A. Verbiscer for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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