A millisecond pulsar in a stellar triple system


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.

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Figure 1: Timing residuals and delays from the PSR J0337+1715 system.
Figure 2: Geometry of the PSR J0337+1715 system at the reference epoch.
Figure 3: Optical, infrared and ultraviolet data on PSR J0337+1715.


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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.

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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.

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Correspondence to S. M. Ransom.

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Ransom, S., Stairs, I., Archibald, A. et al. A millisecond pulsar in a stellar triple system. Nature 505, 520–524 (2014). https://doi.org/10.1038/nature12917

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