Gravitationally bound three-body systems have been studied for hundreds of years1,2 and are common in our Galaxy3,4. They show complex orbital interactions, which can constrain the compositions, masses and interior structures of the bodies5 and test theories of gravity6, if sufficiently precise measurements are available. A triple system containing a radio pulsar could provide such measurements, but the only previously known such system, PSR B1620-26 (refs 7, 8; with a millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of several decades), shows only weak interactions. Here we report precision timing and multiwavelength observations of PSR J0337+1715, a millisecond pulsar in a hierarchical triple system with two other stars. Strong gravitational interactions are apparent and provide the masses of the pulsar (1.4378(13), where is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15) and 0.4101(3)), as well as the inclinations of the orbits (both about 39.2°). The unexpectedly coplanar and nearly circular orbits indicate a complex and exotic evolutionary past that differs from those of known stellar systems. The gravitational field of the outer white dwarf strongly accelerates the inner binary containing the neutron star, and the system will thus provide an ideal laboratory in which to test the strong equivalence principle of general relativity.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    Philosophiae Naturalis Principia Mathematica (Streater, 1687)

  2. 2.

    Moon-Earth-Sun: the oldest three-body problem. Rev. Mod. Phys. 70, 589–639 (1998)

  3. 3.

    , , & Tertiary companions to close spectroscopic binaries. Astron. Astrophys. 450, 681–693 (2006)

  4. 4.

    et al. Triple-star candidates among the Kepler binaries. Astrophys. J. 768, 33 (2013)

  5. 5.

    in Exoplanets (ed. ) 217–238 (Univ. Arizona Press, 2011)

  6. 6.

    & Parametrized post-Newtonian theory of reference frames, multipolar expansions and equations of motion in the N-body problem. Phys. Rep. 400, 209–318 (2004)

  7. 7.

    , , & The triple pulsar system PSR B1620–26 in M4. Astrophys. J. 523, 763–770 (1999)

  8. 8.

    , , , & A young white dwarf companion to pulsar B1620–26: evidence for early planet formation. Science 301, 193–196 (2003)

  9. 9.

    & Formation and evolution of binary and millisecond radio pulsars. Phys. Rep. 203, 1–124 (1991)

  10. 10.

    et al. The Green Bank Telescope 350 MHz drift-scan survey. I. Survey observations and the discovery of 13 pulsars. Astrophys. J. 763, 80 (2013)

  11. 11.

    et al. The Green Bank Telescope 350 MHz drift-scan survey II: data analysis and the timing of 10 new pulsars, including a relativistic binary. Astrophys. J. 763, 81 (2013)

  12. 12.

    & A planetary system around the millisecond pulsar PSR1257+12. Nature 355, 145–147 (1992)

  13. 13.

    confirmation of Earth-mass planets orbiting the millisecond pulsar PSR B1257+12. Science 264, 538–542 (1994)

  14. 14.

    & Pulsar timing and general relativity. Annu. Rev. Astron. Astrophys. 24, 537–575 (1986)

  15. 15.

    On the verification of the planetary system around PSR 1257+12. Astron. J. 105, 1562–1570 (1993)

  16. 16.

    et al. The seventh data release of the Sloan Digital Sky Survey. Astrophys. J. Suppl. Ser. 182, 543–558 (2009)

  17. 17.

    , , & The formation of the eccentric-orbit millisecond pulsar J1903+0327 and the origin of single millisecond pulsars. Astrophys. J. 734, 55 (2011)

  18. 18.

    et al. An eccentric binary millisecond pulsar in the Galactic plane. Science 320, 1309–1312 (2008)

  19. 19.

    et al. On the nature and evolution of the unique binary pulsar J1903+0327. Mon. Not. R. Astron. Soc. 412, 2763–2780 (2011)

  20. 20.

    New developments for modern celestial mechanics - I. General coplanar three-body systems. Application to exoplanets. Mon. Not. R. Astron. Soc. 435, 2187–2226 (2013)

  21. 21.

    , & Secular evolution of hierarchical triple star systems. Astrophys. J. 535, 385–401 (2000)

  22. 22.

    & The hydrodynamical response of a tilted circumbinary disc: linear theory and non-linear numerical simulations. Mon. Not. R. Astron. Soc. 285, 288–302 (1997)

  23. 23.

    & Formation of millisecond pulsars. I. Evolution of low-mass X-ray binaries with Porb > 2 days. Astron. Astrophys. 350, 928–944 (1999)

  24. 24.

    , , & On the mass distribution and birth masses of neutron stars. Astrophys. J. 757, 55 (2012)

  25. 25.

    The nuclear equation of state and neutron star masses. Annu. Rev. Nucl. Particle Sci. 62, 485–515 (2012)

  26. 26.

    The confrontation between general relativity and experiment. Living Rev. Relativ. 9, 3 (2006)

  27. 27.

    , & Tests of the universality of free fall for strongly self-gravitating bodies with radio pulsars. Classical Quant. Grav. 29, 184007 (2012)

  28. 28.

    et al. Discovery of three wide-orbit binary pulsars: implications for binary evolution and equivalence principles. Astrophys. J. 632, 1060–1068 (2005)

  29. 29.

    et al. High-precision timing of five millisecond pulsars: space velocities, binary evolution, and equivalence principles. Astrophys. J. 743, 102 (2011)

  30. 30.

    ATLAS9 Stellar Atmosphere Programs and 2 km/s Grid (Kurucz CD-ROM No. 13., Smithsonian Astrophysical Observatory, 1993)

  31. 31.

    et al. in Advanced Software and Control for Astronomy II (eds & ) (SPIE Conf. Ser. 7019, SPIE, 2008)

  32. 32.

    , & PuMa-II: a wide band pulsar machine for the Westerbork Synthesis Radio Telescope. Proc. Astron. Soc. Pacif. 120, 191–202 (2008)

  33. 33.

    & in Methods in Computational Physics Vol. 14 Radio Astronomy (eds , & ) 55–129 (Academic, 1975)

  34. 34.

    Pulsar timing and relativistic gravity. R. Soc. Lond. Phil. Trans. A 341, 117–134 (1992)

  35. 35.

    , & TEMPO2, a new pulsar-timing package - I. An overview. Mon. Not. R. Astron. Soc. 369, 655–672 (2006)

  36. 36.

    & Asymptotic upper and lower bounds for results of extrapolation methods. Numer. Math. 8, 93–104 (1966)

  37. 37.

    , , & emcee: The MCMC Hammer. Proc. Astron. Soc. Pacif. 125, 306–312 (2013)

  38. 38.

    et al. The calibration and data products of GALEX. Astrophys. J. Suppl. Ser. 173, 682–697 (2007)

  39. 39.

    et al. Design overview and performance of the WIYN High Resolution Infrared Camera (WHIRC). Proc. Astron. Soc. Pacif. 122, 451–469 (2010)

  40. 40.

    et al. The Infrared Array Camera (IRAC) for the Spitzer Space Telescope. Astrophys. J. Suppl. Ser. 154, 10–17 (2004)

  41. 41.

    , & An improved spectroscopic analysis of DA white dwarfs from the Sloan Digital Sky Survey data release 4. Astrophys. J. 730, 128 (2011)

  42. 42.

    & NE2001.I. A new model for the Galactic distribution of free electrons and its fluctuations. Preprint at (2002)

  43. 43.

    Allen’s Astrophysical Quantities 4th edn, 381–396 (AIP Press/Springer, 2000)

  44. 44.

    et al. DiFX-2: a more flexible, efficient, robust, and powerful software correlator. Proc. Astron. Soc. Pacif. 123, 275–287 (2011)

  45. 45.

    et al. The NRAO VLA Sky Survey. Astron. J. 115, 1693–1716 (1998)

  46. 46.

    et al. Precision astrometry with the Very Long Baseline Array: parallaxes and proper motions for 14 pulsars. Astrophys. J. 698, 250–265 (2009)

Download references


We thank D. Levitan and R. Simcoe for providing optical and infrared observations; J. Deneva for early Arecibo telescope observations; P. Bergeron for use of his white dwarf photometry models; K. O’Neil and F. Camilo for approving discretionary time observations on the GBT and the Arecibo telescope, respectively; J. Heyl, E. Algol, and P. Freire for discussions; and G. Kuper, J. Sluman, Y. Tang, G. Jozsa, and R. Smits for their help supporting the WSRT observations. The GBT and VLBA are operated by the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The Arecibo Observatory is operated by SRI International in alliance with Ana G. Méndez-Universidad Metropolitana and the Universities Space Research Association, under a cooperative agreement with the National Science Foundation. The WSRT is operated by the Netherlands Institute for Radio Astronomy (ASTRON). This paper made use of data from the WIYN Observatory at Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy under cooperative agreement with the National Science Foundation. This work is also based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. I.H.S., V.M.K., M.H.v.K. and A.B. acknowledge support from NSERC. A.M.A. and J.W.T.H. acknowledge support from a Vrije Competitie grant from NWO. J.B., D.R.L, V.I.K. and M.A.M. were supported by a WV EPSCoR Research Challenge Grant. V.M.K. acknowledges support from CRAQ/FQRNT, CIFAR, the Canada Research Chairs Program and the Lorne Trottier Chair.

Author information


  1. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia 22903-2475, USA

    • S. M. Ransom
    •  & R. Rosen
  2. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1, Canada

    • I. H. Stairs
    •  & A. Berndsen
  3. Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, The Netherlands

    • A. M. Archibald
    • , J. W. T. Hessels
    • , A. T. Deller
    • , V. I. Kondratiev
    •  & J. van Leeuwen
  4. Department of Physics, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8, Canada

    • A. M. Archibald
    • , R. S. Lynch
    • , C. Karako-Argaman
    •  & V. M. Kaspi
  5. Astronomical Institute ‘Anton Pannekoek’, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands

    • J. W. T. Hessels
    •  & J. van Leeuwen
  6. Physics Department, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, Wisconsin 53201, USA

    • D. L. Kaplan
  7. Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, Wisconsin 53706-1582, USA

    • D. L. Kaplan
    •  & A. Schechtman-Rook
  8. Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, Ontario M5S 3H4, Canada

    • M. H. van Kerkwijk
  9. Department of Physics and Astronomy, West Virginia University, White Hall, Box 6315, Morgantown, West Virginia 26506-6315, USA

    • J. Boyles
    • , D. R. Lorimer
    • , M. A. McLaughlin
    •  & R. Rosen
  10. Physics and Astronomy Department, Western Kentucky University, 1906 College Heights Boulevard, Bowling Green, Kentucky 42101-1077, USA

    • J. Boyles
  11. Center for Radiophysics and Space Research, Cornell University, 524 Space Sciences Building, Ithaca, New York 14853, USA

    • S. Chatterjee
  12. Astro Space Center of the Lebedev Physical Institute, 53 Leninskij Prospekt, Moscow 119991, Russia

    • V. I. Kondratiev
  13. Eureka Scientific Inc., 2452 Delmer Street, Suite 100, Oakland, California 94602-3017, USA

    • M. S. E. Roberts
  14. Physics Department, New York University at Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates

    • M. S. E. Roberts
  15. Department of Physics and Astronomy, University of Texas at Brownsville, One West University Boulevard, Brownsville, Texas 78520, USA

    • K. Stovall
  16. Physics and Astronomy Department, University of New Mexico, 1919 Lomas Boulevard NE, Albuquerque, New Mexico 87131-0001, USA

    • K. Stovall


  1. Search for S. M. Ransom in:

  2. Search for I. H. Stairs in:

  3. Search for A. M. Archibald in:

  4. Search for J. W. T. Hessels in:

  5. Search for D. L. Kaplan in:

  6. Search for M. H. van Kerkwijk in:

  7. Search for J. Boyles in:

  8. Search for A. T. Deller in:

  9. Search for S. Chatterjee in:

  10. Search for A. Schechtman-Rook in:

  11. Search for A. Berndsen in:

  12. Search for R. S. Lynch in:

  13. Search for D. R. Lorimer in:

  14. Search for C. Karako-Argaman in:

  15. Search for V. M. Kaspi in:

  16. Search for V. I. Kondratiev in:

  17. Search for M. A. McLaughlin in:

  18. Search for J. van Leeuwen in:

  19. Search for R. Rosen in:

  20. Search for M. S. E. Roberts in:

  21. Search for K. Stovall in:


S.M.R., M.A.M. and D.R.L. were joint principal investigators of the GBT survey that found the pulsar, and all other authors except D.L.K., M.H.v.K., A.T.D., S.C. and A.S.-R. were members of the survey team who observed and processed data. J.B. found the pulsar in the search candidates. S.M.R. identified the source as a triple, wrote follow-up proposals, observed with the GBT, phase-connected the timing solution and wrote the manuscript. I.H.S. and J.W.T.H. performed timing observations, wrote follow-up proposals and substantially contributed to the initial timing solution. A.M.A. developed the successful timing model and performed the numerical integrations and MCMC analyses. D.L.K. identified the optical counterpart and then, with M.H.v.K. and A.S.-R., performed optical and infrared observations and the multiwavelength analysis. M.H.v.K. and D.L.K. both helped develop parts of the timing model. A.T.D. and S.C. performed the VLBA analysis. All authors contributed to interpretation of the data and the results and to the final version of the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to S. M. Ransom.

About this article

Publication history







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.