Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Planetary system disruption by Galactic perturbations to wide binary stars


Nearly half the exoplanets found within binary star systems reside1 in very wide binaries with average stellar separations greater than 1,000 astronomical units (one astronomical unit (au) being the Earth–Sun distance), yet the influence of such distant binary companions on planetary evolution remains largely unstudied. Unlike their tighter counterparts, the stellar orbits of wide binaries continually change under the influence of the Milky Way’s tidal field and impulses from other passing stars. Here we report numerical simulations demonstrating that the variable nature of wide binary star orbits dramatically reshapes the planetary systems they host, typically billions of years after formation. Contrary to previous understanding2, wide binary companions may often strongly perturb planetary systems, triggering planetary ejections and increasing the orbital eccentricities of surviving planets. Although hitherto not recognized, orbits of giant exoplanets within wide binaries are statistically more eccentric than those around isolated stars. Both eccentricity distributions are well reproduced when we assume that isolated stars and wide binaries host similar planetary systems whose outermost giant planets are scattered beyond about 10 au from their parent stars by early internal instabilities. Consequently, our results suggest that although wide binaries eventually remove the most distant planets from many planetary systems, most isolated giant exoplanet systems harbour additional distant, still undetected planets.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Typical binary-triggered disruption.
Figure 2: Disruption as a function of binary mass and separation.
Figure 3: Eccentricity excitation of planets of wide binaries.

Similar content being viewed by others


  1. Roell, T., Neuhäuser, R., Seifahrt, A. & Mugrauer, M. Extrasolar planets in stellar multiple systems. Astron. Astrophys. 542, A92 (2012)

    Article  ADS  Google Scholar 

  2. Desidera, S. & Barbieri, M. Properties of planets in binary systems. The role of binary separation. Astron. Astrophys. 462, 345–353 (2007)

    Article  ADS  Google Scholar 

  3. Heggie, D. C. & Rasio, F. A. The effect of encounters on the eccentricity of binaries in clusters. Mon. Not. R. Astron. Soc. 282, 1064–1084 (1996)

    Article  ADS  Google Scholar 

  4. Jiang, Y.-F. & Tremaine, S. The evolution of wide binary stars. Mon. Not. R. Astron. Soc. 401, 977–994 (2010)

    Article  ADS  Google Scholar 

  5. Oort, J. H. The structure of the cloud of comets surrounding the Solar System and a hypothesis concerning its origin. Bull. Astron. Inst. Neth. 11, 91–110 (1950)

    ADS  Google Scholar 

  6. Heisler, J. & Tremaine, S. The influence of the galactic tidal field on the Oort comet cloud. Icarus 65, 13–26 (1986)

    Article  ADS  Google Scholar 

  7. Kaib, N. A. & Quinn, T. Reassessing the source of long-period comets. Science 325, 1234–1236 (2009)

    Article  ADS  CAS  Google Scholar 

  8. Adams, F. C. & Laughlin, G. Constraints on the birth aggregate of the Solar System. Icarus 150, 151–162 (2001)

    Article  ADS  Google Scholar 

  9. Zakamska, N. L. & Tremaine, S. Excitation and propagation of eccentricity disturbances in planetary systems. Astron. J. 128, 869–877 (2004)

    Article  ADS  Google Scholar 

  10. Chambers, J. E., Quintana, E. V., Duncan, M. J. & Lissauer, J. J. Symplectic integrator algorithms for modeling planetary accretion in binary star systems. Astron. J. 123, 2884–2894 (2002)

    Article  ADS  Google Scholar 

  11. Lissauer, J. J. Planet formation. Annu. Rev. Astron. Astrophys. 31, 129–172 (1993)

    Article  ADS  CAS  Google Scholar 

  12. Wright, J. T. et al. Ten new and updated multiplanet systems and a survey of exoplanetary systems. Astrophys. J. 693, 1084–1099 (2009)

    Article  ADS  CAS  Google Scholar 

  13. Jurić, M. & Tremaine, S. Dynamical origin of extrasolar planet eccentricity distribution. Astrophys. J. 686, 603–620 (2008)

    Article  ADS  Google Scholar 

  14. Ford, E. B. & Rasio, F. A. Origins of eccentric extrasolar planets: testing the planet-planet scattering model. Astrophys. J. 686, 621–636 (2008)

    Article  ADS  Google Scholar 

  15. Malmberg, D. & Davies, M. B. On the origin of eccentricities among extrasolar planets. Mon. Not. R. Astron. Soc. 394, L26–L30 (2009)

    Article  ADS  Google Scholar 

  16. Raymond, S. N., Armitage, P. J. & Gorelick, N. Planet-planet scattering in planetesimal disks. II. Predictions for outer extrasolar planetary systems. Astrophys. J. 711, 772–795 (2010)

    Article  ADS  Google Scholar 

  17. Kozai, Y. Secular perturbations of asteroids with high inclination and eccentricity. Astron. J. 67, 591–598 (1962)

    Article  ADS  MathSciNet  Google Scholar 

  18. Holman, M., Touma, J. & Tremaine, S. Chaotic variations in the eccentricity of the planet orbiting 16 Cygni B. Nature 386, 254–256 (1997)

    Article  ADS  CAS  Google Scholar 

  19. Wu, Y. & Murray, N. Planet migration and binary companions: the case of HD 80606b. Astrophys. J. 589, 605–614 (2003)

    Article  ADS  Google Scholar 

  20. Fabrycky, D. & Tremaine, S. Shrinking binary and planetary orbits by Kozai cycles with tidal friction. Astrophys. J. 669, 1298–1315 (2007)

    Article  ADS  CAS  Google Scholar 

  21. Marois, C., Zuckerman, B., Konopacky, Q. M., Macintosh, B. & Barman, T. Images of a fourth planet orbiting HR 8799. Nature 468, 1080–1083 (2010)

    Article  ADS  CAS  Google Scholar 

  22. The Microlensing Observations in Astrophysics (MOA) Collaboration & The Optical Gravitational Lensing Experiment (OGLE) Collaboration. Unbound or distant planetary mass population detected by gravitational microlensing. Nature 473, 349–352 (2011)

  23. Eggenberger, A. et al. The impact of stellar duplicity on planet occurrence and properties. I. Observational results of a VLT/NACO search for stellar companions to 130 nearby stars with and without planets. Astron. Astrophys. 474, 273–291 (2007)

    Article  ADS  CAS  Google Scholar 

  24. Raghavan, D. et al. Two suns in the sky: stellar multiplicity in exoplanet systems. Astrophys. J. 646, 523–542 (2006)

    Article  ADS  CAS  Google Scholar 

  25. Mugrauer, M. et al. A search for wide visual companions of exoplanet host stars: the Calar Alto survey. Astron. Nachr. 327, 321–327 (2006)

    Article  ADS  Google Scholar 

  26. Jones, H. R. A. et al. High-eccentricity planets from the Anglo-Australian Planet Search. Mon. Not. R. Astron. Soc. 369, 249–256 (2006)

    Article  ADS  Google Scholar 

  27. Naef, D. et al. HD 80606 b, a planet on an extremely elongated orbit. Astron. Astrophys. 375, L27–L30 (2001)

    Article  ADS  Google Scholar 

  28. Innanen, K. A., Zheng, J. Q., Mikkola, S. & Valtonen, M. J. The Kozai mechanism and the stability of planetary orbits in binary star systems. Astron. J. 113, 1915–1919 (1997)

    Article  ADS  Google Scholar 

  29. Batygin, K., Morbidelli, A. & Tsiganis, K. Formation and evolution of planetary systems in presence of highly inclined stellar perturbers. Astron. Astrophys. 533, A7 (2011)

    Article  ADS  Google Scholar 

  30. Kaib, N. A., Raymond, S. N. & Duncan, M. J. 55 Cancri: a coplanar planetary system that is likely misaligned with its star. Astrophys. J. 742, L24 (2011)

    Article  ADS  Google Scholar 

Download references


We thank J. Chambers and R. Roškar for discussions. This work was funded by a CITA National Fellowship and Canada’s NSERC. S.N.R. thanks the PNP programme of CNRS and the NASA Astrobiology Institute’s Virtual Planetary Laboratory team. Our computing was performed on the SciNet General Purpose Cluster at the University of Toronto.

Author information

Authors and Affiliations



N.A.K. performed the simulations and analysis and was the primary writer of this paper. S.N.R. and M.D. helped initiate the project and advised on simulations and analysis.

Corresponding author

Correspondence to Nathan A. Kaib.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Methods, a Supplementary Discussion, Supplementary Table 1 and Supplementary Figures 1-11. (PDF 430 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kaib, N., Raymond, S. & Duncan, M. Planetary system disruption by Galactic perturbations to wide binary stars. Nature 493, 381–384 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing