Subjects

Abstract

Theories of the formation and early evolution of planetary systems postulate that planets are born in circumstellar disks, and undergo radial migration during and after dissipation of the dust and gas disk from which they formed1,2. The precise ages of meteorites indicate that planetesimals—the building blocks of planets—are produced within the first million years of a star’s life3. Fully formed planets are frequently detected on short orbital periods around mature stars. Some theories suggest that the in situ formation of planets close to their host stars is unlikely and that the existence of such planets is therefore evidence of large-scale migration4,5. Other theories posit that planet assembly at small orbital separations may be common6,7,8. Here we report a newly born, transiting planet orbiting its star with a period of 5.4 days. The planet is 50 per cent larger than Neptune, and its mass is less than 3.6 times that of Jupiter (at 99.7 per cent confidence), with a true mass likely to be similar to that of Neptune. The star is 5–10 million years old and has a tenuous dust disk extending outward from about twice the Earth–Sun separation, in addition to the fully formed planet located at less than one-twentieth of the Earth–Sun separation.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    On the origin of the Solar System. Proc. Natl Acad. Sci. USA 37, 1–14 (1951)

  2. 2.

    & Planet-disk interaction and orbital evolution. Annu. Rev. Astron. Astrophys. 50, 211–249 (2012)

  3. 3.

    et al. The absolute chronology and thermal processing of solids in the solar protoplanetary disk. Science 338, 651–655 (2012)

  4. 4.

    , & Orbital migration of the planetary companion of 51 Pegasi to its present location. Nature 380, 606–607 (1996)

  5. 5.

    Atmospheres of protoplanetary cores: critical mass for nucleated instability. Astrophys. J. 648, 666–682 (2006)

  6. 6.

    & Migration then assembly: formation of Neptune-mass planets inside 1 AU. Astrophys. J. 751, 158 (2012)

  7. 7.

    & Inside-out planet formation. Astrophys. J. 780, 53 (2014)

  8. 8.

    , & The in situ formation of giant planets at short orbital periods. Astrophys. J. 817, L17 (2016)

  9. 9.

    et al. Planetary candidates from the first year of the K2 mission. Astrophys. J. Suppl. Ser. 222, 14 (2016)

  10. 10.

    et al. A nearby M star with three transiting super-Earths discovered by K2. Astrophys. J. 804, 10 (2015)

  11. 11.

    , & A large spectroscopic survey for young low-mass members of the Upper Scorpius OB association. Astron. J. 121, 1040–1049 (2001)

  12. 12.

    , , , & Exploring the full stellar population of the Upper Scorpius OB association. Astron. J. 124, 404–416 (2002)

  13. 13.

    & The disk population of the Upper Scorpius association. Astrophys. J. 758, 31 (2012)

  14. 14.

    , & Measuring the rotation period distribution of field M dwarfs with Kepler. Mon. Not. R. Astron. Soc. 432, 1203–1216 (2013)

  15. 15.

    , & Radial and rotational velocities of young brown dwarfs and very low-mass stars in the Upper Scorpius OB association and the ρ Ophiuchi cloud core. Mon. Not. R. Astron. Soc. 372, 1879–1887 (2006)

  16. 16.

    & Proper motions of cool and ultracool candidate members in the Upper Scorpius OB association. Astron. Astrophys. 504, 981–990 (2009)

  17. 17.

    & Empirical isochrones for low mass stars in nearby young associations. Astrophys. J. 808, 23 (2015)

  18. 18.

    & Intrinsic colors, temperatures, and bolometric corrections of pre-main-sequence stars. Astrophys. J. Suppl. Ser. 208, 9 (2013)

  19. 19.

    , , & New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit. Astron. Astrophys. 577, A42 (2015)

  20. 20.

    & The role of mass and environment in multiple-star formation: a 2MASS survey of wide multiplicity in three young associations. Astrophys. J. 662, 413–430 (2007)

  21. 21.

    Dynamics of protoplanetary disks. Annu. Rev. Astron. Astrophys. 49, 195–236 (2011)

  22. 22.

    , , & Planets around low-mass stars (PALMS). IV. The outer architecture of M dwarf planetary systems. Astrophys. J. Suppl. Ser. 216, 7 (2014)

  23. 23.

    VESPA: false positive probabilities calculator. Astrophys. Source Code Library ascl :1503.011, (2015)

  24. 24.

    , , & Debris disks in the Upper Scorpius OB association. Astrophys. J. 705, 1646–1671 (2009)

  25. 25.

    , , & Evidence for mass-dependent circumstellar disk evolution in the 5 Myr old Upper Scorpius OB association. Astrophys. J. 651, L49–L52 (2006)

  26. 26.

    et al. Debris disks around Sun-like stars. Astrophys. J. 674, 1086–1105 (2008)

  27. 27.

    , , & ALMA observations of circumstellar disks in the Upper Scorpius OB association. Astrophys. J. (in the press); preprint at .

  28. 28.

    & The occurrence rate of small planets around small stars. Astrophys. J. 767, 95 (2013)

  29. 29.

    & The occurrence of potentially habitable planets orbiting M dwarfs estimated from the full Kepler dataset and an empirical measurement of the detection sensitivity. Astrophys. J. 807, 45 (2015)

  30. 30.

    , , , & A HIPPARCOS census of the nearby OB associations. Astron. J. 117, 354–399 (1999)

  31. 31.

    & Nearby young stars selected by proper motion. I. Four new members of the β Pictoris moving group from the Tycho-2 catalog. Astron. J. 137, 3632–3645 (2009)

  32. 32.

    et al. A Magellan MIKE and Spitzer MIPS study of 1.5-1.0M stars in Scorpius-Centaurus. Astrophys. J. 738, 122 (2011)

  33. 33.

    Structure and colour-magnitude diagrams of Scorpius OB2 based on kinematic modelling of Hipparcos data. Mon. Not. R. Astron. Soc. 310, 585–617 (1999)

  34. 34.

    & A unique solution of planet and star parameters from an extrasolar planet transit light curve. Astrophys. J. 585, 1038–1055 (2003)

  35. 35.

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

  36. 36.

    Studies in astronomical time series analysis. II—Statistical aspects of spectral analysis of unevenly spaced data. Astrophys. J. 263, 835–853 (1982)

  37. 37.

    et al. The K2 mission: characterization and early results. Publ. Astron. Soc. Pacif. 126, 398–408 (2014)

  38. 38.

    , , , & K2 discovery of young eclipsing binaries in Upper Scorpius: direct mass and radius determinations for the lowest mass stars and initial characterization of an eclipsing brown dwarf binary. Astrophys. J. 816, 21 (2015)

  39. 39.

    BATMAN: BAsic Transit Model cAlculatioN in Python. Publ. Astron. Soc. Pacif. 127, 1161–1165 (2015)

  40. 40.

    & Analytic light curves for planetary transit searches. Astrophys. J. 580, L171–L175 (2002)

  41. 41.

    , & New limb-darkening coefficients for PHOENIX/1D model atmospheres. I. Calculations for 1500 K ≤ Teff ≤ 4800 K Kepler, CoRot, Spitzer, uvby, UBVRIJHK, Sloan, and 2MASS photometric systems. Astron. Astrophys. 546, A14 (2012)

  42. 42.

    , , & emcee: the MCMC hammer. Publ. Astron. Soc. Pacif. 125, 306–312 (2013)

  43. 43.

    & The effect of starspots on the radii of low-mass pre-main-sequence stars. Mon. Not. R. Astron. Soc. 441, 2111–2123 (2014)

  44. 44.

    et al. Two transiting Earth-size planets near resonance orbiting a nearby cool star. Astrophys. J. 811, 102 (2015)

  45. 45.

    et al. in Instrumentation in Astronomy VIII (eds & ) Proceedings of SPIE Vol. 2198, 362–375, (SPIE, 1994)

  46. 46.

    , , , & Radial velocities for 889 late-type stars. Astrophys. J. Suppl. Ser. 141, 503–522 (2002)

  47. 47.

    , , , & The TRENDS high-contrast imaging survey. IV. The occurrence rate of giant planets around M dwarfs. Astrophys. J. 781, 28 (2014)

  48. 48.

    , , & Detection of stars within ~0.8″ of Kepler objects of interest. Astron. J. 149, 18 (2014)

  49. 49.

    , , , & Michelson interferometry with the Keck I telescope. Publ. Astron. Soc. Pacif. 112, 555–565 (2000)

  50. 50.

    , , & Closure phase in high-resolution optical imaging. Nature 320, 595–597 (1986)

  51. 51.

    et al. Diffraction-limited imaging with ground-based optical telescopes. Astron. J. 95, 1278–1296 (1988)

  52. 52.

    , , & Mapping the shores of the brown dwarf desert. II. Multiple star formation in Taurus-Auriga. Astrophys. J. 731, 8 (2011)

  53. 53.

    et al. Discovery of seven companions to intermediate-mass stars with extreme mass ratios in the Scorpius-Centaurus association. Astrophys. J. 806, L9 (2015)

  54. 54.

    & Multiple star formation to the bottom of the initial mass function. Astrophys. J. 757, 141 (2012)

  55. 55.

    et al. Kepler-21b: a 1.6 REarth planet transiting the bright oscillating F subgiant star HD 179070. Astrophys. J. 746, 123 (2012)

  56. 56.

    , , & Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code. Astron. Astrophys. 436, 895–915 (2005)

  57. 57.

    et al. TRILEGAL, a TRIdimensional modeL of thE GALaxy: status and future. Astrophys. Space Sci. Proc. 26, 165–170 (2012)

  58. 58.

    , , , & The solar neighborhood. XXVIII. The multiplicity fraction of nearby stars from 5 to 70 AU and the brown dwarf desert around M dwarfs. Astron. J. 144, 64 (2012)

  59. 59.

    & The Nearest OB Association: Scorpius-Centaurus (Sco OB2) (ed. ) 235–284, (Astronomical Society of the Pacific Monograph Publications, 2008)

  60. 60.

    in NATO Advanced Science Institutes Series C (eds, & ) Vol. 342, 125–154 (ASI, 1991)

  61. 61.

    & in Birth and Evolution of Massive Stars and Stellar Groups (eds & ) Astrophysics and Space Science Library Vol. 120, 95–101 (Springer, 1985)

  62. 62.

    , & Physical parameters of stars in the Scorpio-Centaurus OB association. Astron. Astrophys. 216, 44–61 (1989)

  63. 63.

    & The history of low-mass star formation in the Upper Scorpius OB association. Astron. J. 117, 2381–2397 (1999)

  64. 64.

    , & A large-area search for low-mass objects in Upper Scorpius. II. Age and mass distributions. Astrophys. J. 688, 377–397 (2008)

  65. 65.

    , & Multi-fibre optical spectroscopy of low-mass stars and brown dwarfs in Upper Scorpius. Astron. Astrophys. 527, A24 (2011)

  66. 66.

    , , & Luminosity functions of young clusters: modeling the substellar mass regime. Astrophys. J. 595, 1222–1230 (2003)

  67. 67.

    Weak and post-T Tauri stars around B-type members of the Scorpius-Centaurus OB association. Astron. J. 115, 351–357 (1998)

  68. 68.

    Kinematics of T Tauri Stars in Nearby Star Forming Regions. PhD thesis, Astronomisches Rechen-Institut Heidelberg (1999);

  69. 69.

    , & A revised age for Upper Scorpius and the star formation history among the F-type members of the Scorpius-Centaurus OB association. Astrophys. J. 746, 154 (2012)

  70. 70.

    et al. The mass-radius relation of young stars. I. USco 5, an M4.5 eclipsing binary in Upper Scorpius observed by K2. Astrophys. J. 807, 3 (2015)

  71. 71.

    et al. An eclipsing double-line spectroscopic binary at the stellar/substellar boundary in the Upper Scorpius OB association. Astron. Astrophys. 584, A128 (2015)

  72. 72.

    Evolution of debris disks. Annu. Rev. Astron. Astrophys. 46, 339–383 (2008)

  73. 73.

    et al. Zodiacal exoplanets in time (ZEIT). I. A Neptune-sized planet orbiting an M4.5 dwarf in the Hyades Star Cluster. Astrophys. J. 818, 46 (2016)

  74. 74.

    et al. New Pleiades eclipsing binaries and a Hyades transiting system identified by K2. Astron. J. 151, 112 (2016)

  75. 75.

    et al. Two “b”s in the beehive: the discovery of the first hot Jupiters in an open cluster. Astrophys. J. 756, L33 (2012)

  76. 76.

    et al. The GAPS programme with HARPS-N at TNG. XI. Pr 0211 in M 44: the first multi-planet system in an open cluster. Astron. Astrophys. 588, A118 (2016)

  77. 77.

    et al. Photometric variability of the T Tauri star TW Hya on time-scales of hours to years. Mon. Not. R. Astron. Soc. 391, 1913–1924 (2008)

  78. 78.

    et al. TW Hydrae: evidence of stellar spots instead of a hot Jupiter. Astron. Astrophys. 489, L9–L13 (2008)

  79. 79.

    et al. Tests of the planetary hypothesis for PTFO 8-8695b. Astrophys. J. 812, 48 (2015)

Download references

Acknowledgements

We thank S. Metchev, K. Batygin, B. Benneke, K. Deck, J. Fuller and A. Shporer for discussions, M. Ireland for software used in the aperture masking analysis, and A. Kraus for contributing to the 2011 Keck/NIRC2 data acquisition. T.J.D. is supported by an NSF Graduate Research Fellowship under Grant DGE1144469. E.A.P. is supported through a Hubble Fellowship. I.J.M.C. is supported through a Sagan Fellowship. A.W.H. acknowledges funding from NASA grant NNX16AE75G and NASA Research Support Agreement 1541779. This paper includes data collected by the Kepler mission, funded by the NASA Science Mission directorate. Some data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. We acknowledge the important cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community and we are fortunate to be able to conduct observations from this mountain.

Author information

Affiliations

  1. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, California 91125, USA

    • Trevor J. David
    • , Lynne A. Hillenbrand
    •  & Scott A. Barenfeld
  2. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA

    • Erik A. Petigura
  3. Joint ALMA Observatory, Avenida Alonso de Córdova 3107, Vitacura, Santiago, Chile

    • John M. Carpenter
  4. Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA

    • Ian J. M. Crossfield
  5. Physics Department, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

    • Sasha Hinkley
  6. NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, California 91125, USA

    • David R. Ciardi
    •  & Charles A. Beichman
  7. Institute for Astronomy, University of Hawai‘i at Maˉnoa, Honolulu, Hawaii 96822, USA

    • Andrew W. Howard
  8. Department of Astronomy, University of California, Berkeley, California 94720, USA

    • Howard T. Isaacson
  9. NASA Ames Research Center, Mountain View, California 94035, USA

    • Ann Marie Cody
    •  & Joshua E. Schlieder

Authors

  1. Search for Trevor J. David in:

  2. Search for Lynne A. Hillenbrand in:

  3. Search for Erik A. Petigura in:

  4. Search for John M. Carpenter in:

  5. Search for Ian J. M. Crossfield in:

  6. Search for Sasha Hinkley in:

  7. Search for David R. Ciardi in:

  8. Search for Andrew W. Howard in:

  9. Search for Howard T. Isaacson in:

  10. Search for Ann Marie Cody in:

  11. Search for Joshua E. Schlieder in:

  12. Search for Charles A. Beichman in:

  13. Search for Scott A. Barenfeld in:

Contributions

T.J.D. noted the object as a young star, prepared the light curve, validated the transit, and led the overall analysis and the writing of the paper. L.A.H. analysed the 2015 and 2016 Keck/HIRES spectra, participated in team organization, performed general analysis, and contributed substantially to the writing of the paper. E.A.P. analysed raw K2 photometry and validated the transit, provided general guidance on exoplanets and false positives, and contributed substantially to the writing of the paper. J.M.C. was involved in the K2 proposal that included the object, and was principal investigator on the 2011 Keck/NIRC2, 2015 Keck/HIRES, and ALMA observations of the object. I.J.M.C. led the transit fitting and VESPA analysis. A.M.C. analysed the raw K2 photometry and validated the transit. A.W.H. and H.T.I. obtained, reduced, and analysed the 2016 Keck/HIRES spectra. D.R.C. led the clear aperture adaptive optics contrast curve analysis for the 2016 and 2011 data. C.A.B. wrote the proposal for 2016 Keck/NIRC2 follow-up of K2 sources and participated in the observations of the object. S.H. analysed the Keck/NIRC2 aperture masking data and assessed the temperature of the circumstellar dust. J.E.S. provided a rotational velocity analysis and calculated the kinematic distance. S.A.B. took the 2015 Keck/HIRES spectrum and analysed the ALMA data (referred to, but published separately in ref. 27).

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Trevor J. David.

Reviewer Information

Nature thanks A. Collier Cameron and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Extended data

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature18293

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.