Tidal fragmentation as the origin of 1I/2017 U1 (‘Oumuamua)

Abstract

The first discovered interstellar object (ISO), ‘Oumuamua (1I/2017 U1) shows a dry and rocky surface, an unusually elongated shape, with short-to-long axis ratio ca 1∕6, a low velocity relative to the local standard of rest (~10 km s−1), non-gravitational accelerations and tumbles on a timescale of a few hours1,2,3,4,5,6,7,8,9. The inferred number density (~3.5 × 1013−2 × 1015 pc−3) for a population of asteroidal ISOs10,11 outnumbers cometary ISOs12 by ≥103, in contrast to the much lower ratio (10−2) of rocky/icy Kuiper belt objects13. Although some scenarios can cause the ejection of asteroidal ISOs14,15, a unified formation theory has yet to comprehensively link all ‘Oumuamua’s puzzling characteristics and to account for the population. Here we show by numerical simulations that ‘Oumuamua-like ISOs can be prolifically produced through extensive tidal fragmentation and ejected during close encounters of their volatile-rich parent bodies with their host stars. Material strength enhanced by the intensive heating during periastron passages enables the emergence of extremely elongated triaxial ISOs with shape ca 1∕10, sizes a ≈ 100 m and rocky surfaces. Although volatiles with low sublimation temperature (such as CO) are concurrently depleted, H2O buried under surfaces is preserved in these ISOs, providing an outgassing source without measurable cometary activities for ‘Oumuamua’s non-gravitational accelerations during its passage through the inner Solar System. We infer that the progenitors of ‘Oumuamua-like ISOs may be kilometre-sized long-period comets from Oort clouds, kilometre-sized residual planetesimals from debris disks or planet-sized bodies at a few astronomical units, orbiting around low-mass main-sequence stars or white dwarfs. These provide abundant reservoirs to account for ‘Oumuamua’s occurrence rate.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Tidal disruption processes and fragmentation outcomes at different periastron distances for the first set of models.
Fig. 2: Fragmentation outcomes of a range of material strengths at dp = 3.5 × 108 m for the first set of models.
Fig. 3: Thermal modelling of a close stellar flyby.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The code used for the thermal analyses is available from the corresponding author upon reasonable request. The PKDGRAV code with granular physics is not yet ready for public release—its details and validation have been presented in many previous studies and are available from the corresponding author upon reasonable request.

References

  1. 1.

    Bannister, M. T. et al. The natural history of ‘Oumuamua. Nat. Astron. 3, 594–602 (2019).

    ADS  Article  Google Scholar 

  2. 2.

    Meech, K. J. et al. A brief visit from a red and extremely elongated interstellar asteroid. Nature 552, 378–381 (2017).

    ADS  Article  Google Scholar 

  3. 3.

    Knight, M. M. et al. On the rotation period and shape of the hyperbolic asteroid 1I/‘Oumuamua (2017 U1) from its lightcurve. Astrophys. J. 851, L31 (2017).

    ADS  Article  Google Scholar 

  4. 4.

    Bolin, B. T. et al. APO time-resolved color photometry of highly elongated interstellar object 1I/‘Oumuamua. Astrophys. J. 852, L2 (2017).

    ADS  Article  Google Scholar 

  5. 5.

    Fraser, W. C. et al. The tumbling rotational state of 1I/‘Oumuamua. Nat. Astron. 2, 383–386 (2018).

    ADS  Article  Google Scholar 

  6. 6.

    Drahus, M. et al. Tumbling motion of 1I/‘Oumuamua and its implications for the body’s distant past. Nat. Astron. 2, 407–412 (2018).

    ADS  Article  Google Scholar 

  7. 7.

    Micheli, M. et al. Non-gravitational acceleration in the trajectory of 1I/2017 U1 (‘Oumuamua). Nature 559, 223–226 (2018).

    ADS  Article  Google Scholar 

  8. 8.

    Trilling, D. E. et al. Spitzer observations of interstellar object 1I/‘Oumuamua. Astron. J. 156, 261 (2018).

    ADS  Article  Google Scholar 

  9. 9.

    Jewitt, D. et al. Interstellar interloper 1I/2017 U1: observations from the NOT and WIYN telescopes. Astrophys. J. 850, L36 (2017).

    ADS  Article  Google Scholar 

  10. 10.

    Do, A., Tucker, M. A. & Tonry, J. Interstellar interlopers: number density and origin of ‘Oumuamua-like objects. Astrophys. J. 855, L10 (2018).

    ADS  Article  Google Scholar 

  11. 11.

    Portegies Zwart, S., Torres, S., Pelupessy, I., Bédorf, J. & Cai, M. X. The origin of interstellar asteroidal objects like 1I/2017 U1 ‘Oumuamua. Mon. Not. R. Astron. Soc. 479, L17–L22 (2018).

    ADS  Article  Google Scholar 

  12. 12.

    Engelhardt, T. et al. An observational upper limit on the interstellar number density of asteroids and comets. Astron. J. 153, 133 (2017).

    ADS  Article  Google Scholar 

  13. 13.

    Weissman, P. R. & Levison, H. F. Origin and evolution of the unusual object 1996 PW: asteroids from the Oort cloud? Astrophys. J. 488, L133–L136 (1997).

    ADS  Article  Google Scholar 

  14. 14.

    Ćuk, M. 1I/‘Oumuamua as a tidal disruption fragment from a binary star system. Astrophys. J. 852, L15 (2018).

    ADS  Article  Google Scholar 

  15. 15.

    Raymond, S. N., Armitage, P. J. & Veras, D. Interstellar object ‘Oumuamua as an extinct fragment of an ejected cometary planetesimal. Astrophys. J. 856, L7 (2018).

    ADS  Article  Google Scholar 

  16. 16.

    Richardson, D. C., Leinhardt, Z. M., Melosh, H. J., Bottke, W. F. & Asphaug, E. in Asteroids III (eds Bottke, W. F. et al.) 501–515 (Univ. Arizona Press, 2002).

  17. 17.

    McNeill, A., Trilling, D. E. & Mommert, M. Constraints on the density and internal strength of 1I/‘Oumuamua. Astrophys. J. 857, L1 (2018).

    ADS  Article  Google Scholar 

  18. 18.

    Sridhar, S. & Tremaine, S. Tidal disruption of viscous bodies. Icarus 95, 86–99 (1992).

    ADS  Article  Google Scholar 

  19. 19.

    Drell, S. D., Foley, H. M. & Ruderman, M. A. Drag and propulsion of large satellites in the ionosphere: an Alfvén propulsion engine in space. J. Geophys. Res. 70, 3131–3145 (1965).

    ADS  MathSciNet  Article  Google Scholar 

  20. 20.

    Fitzsimmons, A. et al. Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 ‘Oumuamua. Nat. Astron. 2, 133–137 (2018).

    ADS  Article  Google Scholar 

  21. 21.

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

    ADS  Article  Google Scholar 

  22. 22.

    Punzo, D., Capuzzo-Dolcetta, R. & Portegies Zwart, S. The secular evolution of the Kuiper belt after a close stellar encounter. Mon. Not. R. Astron. Soc. 444, 2808–2819 (2014).

    ADS  Article  Google Scholar 

  23. 23.

    Coughlin, J. L. et al. Planetary candidates observed by Kepler. VII. The first fully uniform catalog based on the entire 48-month data set (Q1-Q17 DR24). Astrophys. J. Suppl. Ser. 224, 12 (2016).

    ADS  Article  Google Scholar 

  24. 24.

    Cassan, A. et al. One or more bound planets per Milky Way star from microlensing observations. Nature 481, 167–169 (2012).

    ADS  Article  Google Scholar 

  25. 25.

    Nagasawa, M., Ida, S. & Bessho, T. Formation of hot planets by a combination of planet scattering, tidal circularization, and the Kozai mechanism. Astrophys. J. 678, 498–508 (2008).

    ADS  Article  Google Scholar 

  26. 26.

    Ida, S., Lin, D. N. C. & Nagasawa, M. Toward a deterministic model of planetary formation. VII. Eccentricity distribution of gas giants. Astrophys. J. 775, 42 (2013).

    ADS  Article  Google Scholar 

  27. 27.

    Charbonneau, D. et al. A super-Earth transiting a nearby low-mass star. Nature 462, 891–894 (2009).

    ADS  Article  Google Scholar 

  28. 28.

    Davies, M. B. et al. in Protostars and Planets VI (eds Beuther, H. et al.) 787–808 (Univ. Arizona Press, 2014).

  29. 29.

    Rafikov, R. R. 1I/2017 ‘Oumuamua-like interstellar asteroids as possible messengers from dead stars. Astrophys. J. 861, 35 (2018).

    ADS  Article  Google Scholar 

  30. 30.

    Veras, D., Wyatt, M. C., Mustill, A. J., Bonsor, A. & Eldridge, J. J. The great escape: how exoplanets and smaller bodies desert dying stars. Mon. Not. R. Astron. Soc. 417, 2104–2123 (2011).

    ADS  Article  Google Scholar 

  31. 31.

    Richardson, D. C., Quinn, T., Stadel, J. & Lake, G. Direct large-scale N-body simulations of planetesimal dynamics. Icarus 143, 45–59 (2000).

    ADS  Article  Google Scholar 

  32. 32.

    Stadel, J. G. Cosmological N-body Simulations and Their Analysis. PhD thesis, Univ. Washington (2001).

  33. 33.

    Schwartz, S. R., Richardson, D. C. & Michel, P. An implementation of the soft-sphere discrete element method in a high-performance parallel gravity tree-code. Granul. Matter 14, 363–380 (2012).

    Article  Google Scholar 

  34. 34.

    Zhang, Y. et al. Creep stability of the proposed AIDA mission target 65803 didymos: I. Discrete cohesionless granular physics model. Icarus 294, 98–123 (2017).

    ADS  Article  Google Scholar 

  35. 35.

    Zhang, Y. et al. Rotational failure of rubble-pile bodies: influences of shear and cohesive strengths. Astrophys. J. 857, 15 (2018).

    ADS  Article  Google Scholar 

  36. 36.

    Chau, K. T., Wong, R. H. C. & Wu, J. J. Coefficient of restitution and rotational motions of rockfall impacts. Int. J. Rock Mech. Min. Sci. 39, 69–77 (2002).

    Article  Google Scholar 

  37. 37.

    Jiang, M., Shen, Z. & Wang, J. A novel three-dimensional contact model for granulates incorporating rolling and twisting resistances. Comput. Geotech. 65, 147–163 (2015).

    Article  Google Scholar 

  38. 38.

    Schwartz, S. R., Michel, P. & Richardson, D. C. Numerically simulating impact disruptions of cohesive glass bead agglomerates using the soft-sphere discrete element method. Icarus 226, 67–76 (2013).

    ADS  Article  Google Scholar 

  39. 39.

    Poppe, T. Sintering of highly porous silica-particle samples: analogues of early Solar-System aggregates. Icarus 164, 139–148 (2003).

    ADS  Article  Google Scholar 

  40. 40.

    Holsapple, K. A. & Michel, P. Tidal disruptions II: a continuum theory for solid bodies with strength, with applications to the Solar System. Icarus 193, 283–301 (2008).

    ADS  Article  Google Scholar 

  41. 41.

    Ramírez, I. et al. The dissimilar chemical composition of the planet-hosting stars of the XO-2 binary system. Astrophys. J. 808, 13 (2015).

    ADS  Article  Google Scholar 

  42. 42.

    Kalirai, J. S. et al. The masses of population II white dwarfs. Astrophys. J. 705, 408–425 (2009).

    ADS  Article  Google Scholar 

  43. 43.

    Scheeres, D. J., Ostro, S. M., Werner, R. A., Asphaug, E. & Hudson, R. S. Effects of gravitational interactions on asteroid spin states. Icarus 147, 106–118 (2000).

    ADS  Article  Google Scholar 

  44. 44.

    Belton, M. J. et al. The excited spin state of 1I/2017 U1 ‘Oumuamua. Astrophys. J. 856, L21 (2018).

    ADS  Article  Google Scholar 

  45. 45.

    Mashchenko, S. Modelling the light curve of ‘Oumuamua: evidence for torque and disc-like shape. Mon. Not. R. Astron. Soc. 489, 3003–3021 (2019).

    ADS  Article  Google Scholar 

  46. 46.

    Ďurech, J., Sidorin, V. & Kaasalainen, M. DAMIT: a database of asteroid models. Astron. Astrophys. 513, A46 (2010).

    ADS  Article  Google Scholar 

  47. 47.

    Harris, A. W. Tumbling asteroids. Icarus 107, 209–211 (1994).

    ADS  Article  Google Scholar 

  48. 48.

    Veras, D. Post-main-sequence planetary system evolution. R. Soc. Open Sci. 3, 150571 (2016).

    ADS  MathSciNet  Article  Google Scholar 

  49. 49.

    Chen, D.-C. et al. A power-law decay evolution scenario for polluted single white dwarfs. Nat. Astron. 3, 69–75 (2019).

    ADS  Article  Google Scholar 

  50. 50.

    Weissman, P. R. Cometary impacts with the Sun: physical and dynamical considerations. Icarus 55, 448–454 (1983).

    ADS  Article  Google Scholar 

  51. 51.

    Hui, M.-T. & Knight, M. M. New insights into interstellar object 1I/2017 U1 (‘Oumuamua) from SOHO/STEREO nondetections. Astron. J. 158, 256 (2019).

    ADS  Article  Google Scholar 

  52. 52.

    Spitzer, L. & Schwarzschild, M. The possible influence of interstellar clouds on stellar velocities. II. Astrophys. J. 118, 106 (1953).

    ADS  Article  Google Scholar 

  53. 53.

    Holmberg, J., Nordström, B. & Andersen, J. The Geneva-Copenhagen survey of the solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age–metallicity diagram, and heating mechanisms of the disk. Astron. Astrophys. 475, 519–537 (2007).

    ADS  Article  Google Scholar 

  54. 54.

    Draine, B. T. Physics of the Interstellar and Intergalactic Medium (Princeton Univ. Press, 2011).

  55. 55.

    Bialy, S. & Loeb, A. Could solar radiation pressure explain ‘Oumuamua’s peculiar acceleration? Astrophys. J. 868, L1 (2018).

    ADS  Article  Google Scholar 

  56. 56.

    Eubanks, T. M. High-drag interstellar objects and galactic dynamical streams. Astrophys. J. 874, L11 (2019).

    ADS  Article  Google Scholar 

  57. 57.

    Heiles, C. & Crutcher, R. in Cosmic Magnetic Fields (eds Wielebinski R. & Beck R.) 137–182 (Springer, 2005).

  58. 58.

    Neubauer, F. M. Nonlinear standing Alfvén wave current system at Io: theory. J. Geophys. Res. 85, 1171–1178 (1980).

    ADS  Article  Google Scholar 

  59. 59.

    Wang, D. & Karato, S.-i Electrical conductivity of talc aggregates at 0.5 GPa: influence of dehydration. Phys. Chem. Miner. 40, 11–17 (2013).

    ADS  Article  Google Scholar 

  60. 60.

    Laine, R. O., Lin, D. N. C. & Dong, S. Interaction of close-in planets with the magnetosphere of their host stars. I. Diffusion, ohmic dissipation of time-dependent field, planetary inflation, and mass loss. Astrophys. J. 685, 521–542 (2008).

    ADS  Article  Google Scholar 

  61. 61.

    Rafikov, R. R., Gurevich, A. V. & Zybin, K. P. Inductive interaction of rapidly rotating conductive bodies with a magnetized plasma. J. Exp. Theor. Phys. 88, 297–308 (1999).

    ADS  Article  Google Scholar 

  62. 62.

    Ye, Q.-Z., Zhang, Q., Kelley, M. S. P. & Brown, P. G. 1I/2017 U1 (‘Oumuamua) is hot: imaging, spectroscopy, and search of meteor activity. Astrophys. J. 851, L5 (2017).

    ADS  Article  Google Scholar 

  63. 63.

    Park, R. S., Pisano, D. J., Lazio, T. J. W., Chodas, P. W. & Naidu, S. P. Search for OH 18 cm radio emission from 1I/2017 U1 with the Green Bank Telescope. Astron. J. 155, 185 (2018).

    ADS  Article  Google Scholar 

  64. 64.

    Seligman, D., Laughlin, G. & Batygin, K. On the anomalous acceleration of 1I/2017 U1 ‘Oumuamua. Astrophys. J. 876, L26 (2019).

    ADS  Article  Google Scholar 

  65. 65.

    Sekanina, Z. Outgassing as trigger of 1I/‘Oumuamua’s nongravitational acceleration: could this hypothesis work at all? Preprint at http://arxiv.org/abs/1905.00935 (2019).

  66. 66.

    Wilson, D. J., Gänsicke, B. T., Farihi, J. & Koester, D. Carbon to oxygen ratios in extrasolar planetesimals. Mon. Not. R. Astron. Soc. 459, 3282–3286 (2016).

    ADS  Article  Google Scholar 

  67. 67.

    Sandford, S. A., Allamandola, L. J. & Geballe, T. R. Spectroscopic detection of molecular hydrogen frozen in interstellar ices. Science 262, 400–402 (1993).

    ADS  Article  Google Scholar 

  68. 68.

    Chabrier, G. Galactic stellar and substellar initial mass function. Publ. Astron. Soc. Pac. 115, 763–795 (2003).

    ADS  Article  Google Scholar 

  69. 69.

    Hayashi, C., Nakazawa, K. & Nakagawa, Y. in Protostars and Planets II (eds Black, D. C. & Matthews, M. S.) 1100–1153 (Univ. Arizona Press, 1985).

  70. 70.

    Guzik, P. et al. Initial characterization of interstellar comet 2I/Borisov. Nat. Astron. 4, 53–57 (2019).

    ADS  Article  Google Scholar 

  71. 71.

    Zhou, J.-L. & Lin, D. N. C. Planetesimal accretion onto growing proto-gas giant planets. Astrophys. J. 666, 447–465 (2007).

    ADS  Article  Google Scholar 

  72. 72.

    Hanse, J., Jílková, L., Portegies Zwart, S. F. & Pelupessy, F. I. Capture of exocomets and the erosion of the Oort cloud due to stellar encounters in the Galaxy. Mon. Not. R. Astron. Soc. 473, 5432–5445 (2017).

    ADS  Article  Google Scholar 

  73. 73.

    Everhart, E. Intrinsic distributions of cometary perihelia and magnitudes. Astron. J. 72, 1002–1011 (1967).

    ADS  Article  Google Scholar 

  74. 74.

    Francis, P. J. The demographics of long-period comets. Astrophys. J. 635, 1348–1361 (2005).

    ADS  Article  Google Scholar 

  75. 75.

    Neslušan, L. The fading problem and the population of the Oort cloud. Astron. Astrophys. 461, 741–750 (2007).

    ADS  Article  Google Scholar 

  76. 76.

    Raymond, S. N., Armitage, P. J., Veras, D., Quintana, E. V. & Barclay, T. Implications of the interstellar object 1I/‘Oumuamua for planetary dynamics and planetesimal formation. Mon. Not. R. Astron. Soc. 476, 3031–3038 (2018).

    ADS  Article  Google Scholar 

  77. 77.

    Manser, C. J. et al. A planetesimal orbiting within the debris disc around a white dwarf star. Science 364, 66–69 (2019).

    ADS  Article  Google Scholar 

  78. 78.

    Mróz, P. et al. Two new free-floating or wide-orbit planets from microlensing. Astron. Astrophys. 622, A201 (2019).

    Article  Google Scholar 

  79. 79.

    Guimarães, A. H. F. et al. Aggregates in the strength and gravity regime: particles sizes in Saturn’s rings. Icarus 220, 660–678 (2012).

    ADS  Article  Google Scholar 

  80. 80.

    Wu, Y. & Lithwick, Y. Secular chaos and the production of hot Jupiters. Astrophys. J. 735, 109 (2011).

    ADS  Article  Google Scholar 

  81. 81.

    Gasc, S. et al. Change of outgassing pattern of 67P/Churyumov-Gerasimenko during the March 2016 equinox as seen by ROSINA. Mon. Not. R. Astron. Soc. 469, S108–S117 (2017).

    Article  Google Scholar 

  82. 82.

    Lesher, C. E. & Spera, F. J. in The Encyclopedia of Volcanoes (eds Sigurdsson, H. et al.) 113–141 (Academic Press, 2015).

Download references

Acknowledgements

Y.Z. acknowledges funding from the Université Côte d’Azur ‘Individual grants for young researchers’ programme of IDEX JEDI. D.N.C.L. thanks the Institute for Advanced Study, Princeton, for support while this work was initiated. We thank S. Tremaine for inspiration and suggestions, D.C. Richardson for assistance with the PKDGRAV code, G. Laughlin, P. Michel, S.-F. Liu, R. Rafikov and S. Portegies Zwart for constructive feedback on the results and implications of this work. Simulations were carried out at the University of Maryland on the yorp cluster administered by the Department of Astronomy and the Deepthought and Deepthought2 supercomputing clusters administered by the Division of Informational Technology. For data visualization, we made use of the freeware, multiplatform, ray-tracing package, Persistence of Vision Raytracer.

Author information

Affiliations

Authors

Contributions

Y.Z. performed the soft-sphere/N-body numerical simulations and the thermal modelling, and analysed the numerical results and implications for ‘Oumuamua. D.N.C.L. initiated the collaboration to study tidal disruption as a formation mechanism for ‘Oumuamua, and contributed to address questions on ISOs’ population and dynamical origins. Both authors contributed to interpretation of ‘Oumuamua’s properties and preparation of the manuscript.

Corresponding author

Correspondence to Yun Zhang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

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

Supplementary information

41550_2020_1065_MOESM2_ESM.mp4

Evolution of a non-cohesive rubble-pile parent body during a close stellar flyby.

41550_2020_1065_MOESM3_ESM.mp4

Tidal encounter evolution of a cohesive rubble-pile parent body.

41550_2020_1065_MOESM4_ESM.mp4

Tidal disruption of a rubble-pile parent body with evolving cohesive strength.

Supplementary Information

Supplementary discussion and Figs. 1–6, and the legends for Supplementary Videos 1–3.

Supplementary Video 1

Evolution of a non-cohesive rubble-pile parent body during a close stellar flyby.

Supplementary Video 2

Tidal encounter evolution of a cohesive rubble-pile parent body.

Supplementary Video 3

Tidal disruption of a rubble-pile parent body with evolving cohesive strength.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Zhang, Y., Lin, D.N.C. Tidal fragmentation as the origin of 1I/2017 U1 (‘Oumuamua). Nat Astron (2020). https://doi.org/10.1038/s41550-020-1065-8

Download citation

Further reading