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Hit-and-run planetary collisions

Nature volume 439, pages 155–160 (2006)Cite this article

Abstract

Terrestrial planet formation is believed to have concluded in our Solar System with about 10 million to 100 million years of giant impacts, where hundreds of Moon- to Mars-sized planetary embryos acquired random velocities through gravitational encounters and resonances with one another and with Jupiter. This led to planet-crossing orbits and collisions that produced the four terrestrial planets, the Moon and asteroids. But here we show that colliding planets do not simply merge, as is commonly assumed. In many cases, the smaller planet escapes from the collision highly deformed, spun up, depressurized from equilibrium, stripped of its outer layers, and sometimes pulled apart into a chain of diverse objects. Remnants of these ‘hit-and-run’ collisions are predicted to be common among remnant planet-forming populations, and thus to be relevant to asteroid formation and meteorite petrogenesis.

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Figure 1: Planetary embryos of comparable diameter are believed to have collided in giant impacts in the late stage of Solar System formation.
Figure 2: A Moon-sized differentiated planet ( M = 0.01 M ⊕ ) grazing a Mars-sized (0.1 M ⊕ ) planet, resulting in mass loss, spin-up and global pressure unloading.
Figure 3: Two typical collisions involving differentiated planetary embryos.
Figure 4: The pressures at which degassing initiates.

References

  1. Agnor, C. & Asphaug, E. Accretion efficiency during planetary collisions. Astrophys. J. 613, L157–L160 (2004)

    Article  ADS  Google Scholar 

  2. Wetherill, G. W. Occurrence of giant impacts during the growth of the terrestrial planets. Science 228, 877–879 (1985)

    Article  CAS  ADS  Google Scholar 

  3. Agnor, C. B., Canup, R. M. & Levison, H. F. On the character and consequences of large impacts in the late stage of terrestrial planet formation. Icarus 142, 219–237 (1999)

    Article  ADS  Google Scholar 

  4. Greenberg, R., Hartmann, W. K., Chapman, C. R. & Wacker, J. F. Planetesimals to planets—Numerical simulations of collisional evolution. Icarus 35, 1–26 (1978)

    Article  ADS  Google Scholar 

  5. Weidenschilling, S. J., Spaute, D., Davis, D. R., Marzari, F. & Ohtsuki, K. Accretion evolution of a planetesimals swarm. Icarus 128, 429–455 (1997)

    Article  ADS  Google Scholar 

  6. Kokubo, E. & Ida, S. Formation of protoplanetary systems and diversity of planetary systems. Astrophys. J. 581, 666–680 (2002)

    Article  ADS  Google Scholar 

  7. Pierazzo, E. & Melosh, H. J. Hydrocode modelling of oblique impacts: The fate of the projectile. Meteorit. Planet. Sci. 35, 117–130 (2000)

    Article  CAS  ADS  Google Scholar 

  8. Stevenson, D. J. Origin of the moon—The collision hypothesis. Annu. Rev. Earth Planet. Sci. 15, 271–315 (1987)

    Article  ADS  Google Scholar 

  9. Canup, R. M. Dynamics of lunar formation. Annu. Rev. Astron. Astrophys. 42, 441–475 (2004)

    Article  ADS  Google Scholar 

  10. Canup, R. & Asphaug, E. Origin of the Moon in a giant impact near the end of the Earth's formation. Nature 412, 708–712 (2001)

    Article  CAS  ADS  Google Scholar 

  11. Asphaug, E. & Benz, W. Size, density, and structure of comet Shoemaker-Levy 9 inferred from the physics of tidal breakup. Icarus 121, 225–248 (1996)

    Article  ADS  Google Scholar 

  12. Jeffreys, H. The relation of cohesion to Roche's limit. Mon. Not. R. Astron. Soc. 107, 260–262 (1947)

    Article  ADS  Google Scholar 

  13. McKinnon, W. B. & Schenk, P. M. Estimates of comet fragment masses from impact crater chains on Callisto and Ganymede. Geophys. Res. Lett. 22, 1829–1832 (1995)

    Article  ADS  Google Scholar 

  14. Boss, A. P., Cameron, A. G. W. & Benz, W. Tidal disruption of inviscid planetesimals. Icarus 92, 165–178 (1991)

    Article  ADS  Google Scholar 

  15. Rettig, T. W., Mumma, M. J., Sobczak, G. J., Hahn, J. M. & DiSanti, M. The nature of Comet Shoemaker-Levy/9 subnuclei from analysis of preimpact Hubble Space Telescope images. J. Geophys. Res. 101, 9271–9281 (1996)

    Article  CAS  ADS  Google Scholar 

  16. Abe, Y., Ohtani, E., Okuchi, T., Righter, K. & Drake, M. in Origin of the Earth and Moon (eds Canup, R. & Righter, K.) 413–433 (Univ. Arizona Press, Tucson, 2000)

    Google Scholar 

  17. Wilson, L. Relationships between pressure, volatile content and ejecta velocity in three types of volcanic explosion. J. Volcanol. Geotherm. Res. 8, 297–313 (1980)

    Article  ADS  Google Scholar 

  18. Jeans, J. H. Problems of Cosmogony and Stellar Dynamics (Cambridge Univ. Press, Cambridge, 1919)

    MATH  Google Scholar 

  19. Benz, W. in The Numerical Modeling of Nonlinear Stellar Pulsations: Problems and Prospects (ed. Buchler, J. R.) 269–288 (Kluwer Academic, Boston, 1990)

    Book  Google Scholar 

  20. Asphaug, E., Agnor, C. & Williams, Q. Tidal forces as drivers of collisional evolution. Lunar Planet. Sci. Conf. XXXVI abstr. 2393 (2005); http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2393.pdf (2005)

  21. Mizuno, H. & Boss, A. P. Tidal disruption of dissipative planetesimals. Icarus 63, 109–133 (1985)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  23. Grady, D. E. & Kipp, M. E. Continuum modeling of explosive fracture in oil shale. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 17, 147–157 (1980)

    Article  Google Scholar 

  24. Asphaug, E., Ryan, E. & Zuber, M. in Asteroids III Table I (eds Bottke, W. F. Jr, Cellino, A., Paolicchi, P. & Binzel, R. P.) 463–484 (Univ. Arizona Press, Tucson, 2002)

    Google Scholar 

  25. Burbine, T. H., Meibom, A. & Binzel, R. P. Mantle material in the main belt: Battered to bits? Meteoritics 31, 607–620 (1996)

    Article  CAS  Google Scholar 

  26. Mei, S., Bai, W., Hiraga, T. & Kohlstedt, D. L. Influence of melt on the creep behaviour of olivine-basalt aggregates under hydrous conditions. Earth Planet. Sci. Lett. 201, 491–507 (2002)

    Article  CAS  ADS  Google Scholar 

  27. Walzer, U., Hendel, R. & Baumgardner, J. The effects of a variation of the radial viscosity profile on mantle evolution. Tectonophysics 384, 55–90 (2004)

    Article  ADS  Google Scholar 

  28. Tackley, P. J. Convection in Io's asthenosphere: Redistribution of nonuniform tidal heating by mean flows. J. Geophys. Res. 106, 32971–32982 (2001)

    Article  ADS  Google Scholar 

  29. Wetherill, G. W. An alternative model for the formation of the asteroids. Icarus 100, 307–325 (1992)

    Article  ADS  Google Scholar 

  30. Bottke, W. F. et al. The fossilized size distribution of the main asteroid belt. Icarus 175, 111–140 (2005)

    Article  ADS  Google Scholar 

  31. McCoy, T. J. et al. A petrologic and isotopic study of lodranites: Evidence for early formation as partial melt residues from heterogeneous precursors. Geochim. Cosmochim. Acta 61, 623–637 (1997)

    Article  CAS  ADS  Google Scholar 

  32. Haack, H., Scott, E. R. D. & Rasmussen, K. L. Thermal and shock history of mesosiderites and their large parent asteroid. Geochim. Cosmochim. Acta 60, 2609–2619 (1996)

    Article  CAS  ADS  Google Scholar 

  33. Wilson, L., Keil, K., Browning, L. B., Krot, A. N. & Bourcier, W. Early aqueous alteration, explosive disruption, and re-processing of asteroids. Meteorit. Planet. Sci. 34, 541–557 (1999)

    Article  CAS  ADS  Google Scholar 

  34. Keil, K., Stöffler, D., Love, S. G. & Scott, E. R. D. Constraints on the role of impact heating and melting in asteroids. Meteoritics 32, 349–363 (1997)

    Article  CAS  Google Scholar 

  35. Ostro, S. J. et al. Radar observations of asteroid 216 Kleopatra. Science 288, 836–839 (2000)

    Article  CAS  ADS  Google Scholar 

  36. Rivkin, A. S., Howell, E. S., Lebofsky, L. A., Clark, B. E. & Britt, D. T. The nature of M-class asteroids from 3-µm observations. Icarus 145, 351–368 (2000)

    Article  CAS  ADS  Google Scholar 

  37. Davis, D. R., Chapman, C. R., Greenberg, R. & Weidenschilling, S. J. Collisional history of asteroids: Evidence from Vesta and the Hirayama families. Icarus 62, 30–53 (1985)

    Article  ADS  Google Scholar 

  38. Dohnanyi, J. W. Collisional models of asteroids and their debris. J. Geophys. Res. 74, 2531–2554 (1969)

    Article  ADS  Google Scholar 

  39. Binzel, R. P. et al. Geologic mapping of Vesta from 1994 Hubble Space Telescope images. Icarus 128, 95–103 (1997)

    Article  ADS  Google Scholar 

  40. Greenwood, R. C., Franchi, I. A., Jambon, A. & Buchanan, P. C. Widespread magma oceans on asteroidal bodies in the early Solar System. Nature 435, 916–919 (2005)

    Article  CAS  ADS  Google Scholar 

  41. Rivers, M. L. & Carmichael, I. S. E. Ultrasonic studies of silicate melts. J. Geophys. Res. 92, 9247–9270 (1987)

    Article  CAS  ADS  Google Scholar 

  42. Ochs, F. A. III & Lange, R. A. The density of hydrous magmatic liquids. Science 283, 1314–1317 (1999)

    Article  CAS  ADS  Google Scholar 

  43. Dixon, J. E., Stolper, E. M. & Holloway, J. R. An experimental study of water and carbon dioxide solubilities in mid-ocean ridge basaltic liquids. Part I. Calibration and solubility models. J. Petrol. 36, 1607–1631 (1995)

    CAS  Google Scholar 

  44. Benz, W. & Asphaug, E. Catastrophic disruptions revisited. Icarus 142, 5–20 (1999)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This research was sponsored by NASA's Planetary Geology and Geophysics Program, “Small Bodies and Planetary Collisions”. We benefited from discussions with a number of colleagues, including W. F. Bottke and R. Canup. We particularly thank D. Stevenson and K. Zahnle for comments on the manuscript.

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  1. Earth Sciences Department, Institute for Geophysics and Planetary Physics, University of California, 1156 High St, California, 95064, Santa Cruz, USA

    Erik Asphaug, Craig B. Agnor & Quentin Williams

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  1. Erik Asphaug
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Correspondence to Erik Asphaug.

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Asphaug, E., Agnor, C. & Williams, Q. Hit-and-run planetary collisions. Nature 439, 155–160 (2006). https://doi.org/10.1038/nature04311

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