The ice-giant planet Uranus probably underwent a giant impact, given that its spin axis is tilted by 98 degrees1,2,3. That its satellite system is equally inclined and prograde suggests that it was formed as a consequence of the impact. However, the disks predicted by the impact simulations1,3,4 generally have sizes one order smaller and masses two orders larger than those of the observed system at present. Here we show, by means of a theoretical model, that the Uranian satellite formation is regulated by the evolution of the impact-generated disk. Because the vaporization temperature of water ice is low and both Uranus and the impactor are assumed to be ice-dominated, we can conclude that the impact-generated disk has mostly vaporized. We predict that the disk lost a substantial amount of water vapour mass and spread to the levels of the current system until the disk cooled down enough for ice condensation and accretion of icy particles to begin. From the predicted distribution of condensed ices, our N-body simulation is able to reproduce the observed mass–orbit configuration of Uranian satellites. This scenario contrasts with the giant-impact model for the Earth’s Moon5, in which about half of the compact, impact-generated, solid or liquid disk is immediately incorporated into the Moon on impact6.
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
The codes used in this study are available from the corresponding author upon reasonable request.
Slattery, W. L., Benz, W. & Cameron, A. G. W. Giant impacts on a primitive Uranus. Icarus 99, 167–174 (1992).
Kurosaki, K. & Inutsuka, S.-i The exchange of mass and angular momentum in the impact event of ice giant planets: implications for the origin of Uranus. Astron. J. 157, 13 (2019).
Reinhardt, C., Chau, A., Stadel, J. & Helled, R. Bifurcation in the history of Uranus and Neptune: the role of giant impacts. Mon. Not. R. Astron. Soc. 492, 5336–5353 (2020).
Kegerreis, J. A. et al. Consequences of giant impacts on early Uranus for rotation, internal structure, debris, and atmospheric erosion. Astrophys. J. 861, 52 (2018).
Canup, R. M. & Asphaug, E. Origin of the Moon in a giant impact near the end of the Earth’s formation. Nature 412, 708–712 (2001).
Ida, S., Canup, R. M. & Stewart, G. R. Lunar accretion from an impact-generated disk. Nature 389, 353–357 (1997).
Dermott, S. F., Malhotra, R. & Murray, C. D. Dynamics of the Uranian and Saturnian satellite systems: a chaotic route to melting Miranda? Icarus 76, 295–334 (1988).
Hussmann, H., Sohl, F. & Spohn, T. Subsurface oceans and deep interiors of medium-sized outer planet satellites and large trans-Neptunian objects. Icarus 185, 258–273 (2006).
Podolak, M., Weizman, A. & Marley, M. Comparative models of Uranus and Neptune. Planet. Space Sci. 43, 1517–1522 (1995).
Szulágyi, J., Cilibrasi, M. & Mayer, L. In situ formation of icy moons of Uranus and Neptune. Astrophys. J. 868, L13 (2018).
Morbidelli, A., Tsiganis, K., Batygin, K., Crida, A. & Gomes, R. Explaining why the Uranian satellites have equatorial prograde orbits despite the large planetary obliquity. Icarus 219, 737–740 (2012).
Hartmann, L., Calvet, N., Gullbring, E. & D’Alessio, P. Accretion and the evolution of T Tauri disks. Astrophys. J. 495, 385–400 (1998).
Shakura, N. I. & Sunyaev, R. A. Black holes in binary systems. Observational appearance. Astron. Astrophys. 500, 33–51 (1973).
Lynden-Bell, D. & Pringle, J. E. The evolution of viscous discs and the origin of the nebular variables. Mon. Not. R. Astron. Soc. 168, 603–637 (1974).
Nakagawa, Y., Sekiya, M. & Hayashi, C. Settling and growth of dust particles in a laminar phase of a low-mass solar nebula. Icarus 67, 375–390 (1986).
Melosh, H. J. A hydrocode equation of state for SiO2. Meteorit. Planet. Sci. 42, 2079–2098 (2007).
Blum, J. & Wurm, G. Experiments on sticking, restructuring, and fragmentation of preplanetary dust aggregates. Icarus 143, 138–146 (2000).
Kokubo, E. & Ida, S. Formation of protoplanets from planetesimals in the solar nebula. Icarus 143, 15–27 (2000).
Ishizawa, Y., Sasaki, T. & Hosono, N. Can the Uranian satellites form from a debris disk generated by a giant impact? Astrophys. J. 885, 132 (2019).
Agnor, C. B. & Hamilton, D. P. Neptune’s capture of its moon Triton in a binary-planet gravitational encounter. Nature 441, 192–194 (2006).
Rogers, L. A. Most 1.6 Earth-radius planets are not rocky. Astrophys. J. 801, 41 (2015).
Ormel, C. W. & Cuzzi, J. N. Closed-form expressions for particle relative velocities induced by turbulence. Astron. Astrophys. 466, 413–420 (2007).
Dubrulle, B., Morfill, G. & Sterzik, M. The dust subdisk in the protoplanetary nebula. Icarus 114, 237–246 (1995).
Lichtenegger, H. I. M. & Komle, N. I. Heating and evaporation of icy particles in the vicinity of comets. Icarus 90, 319–325 (1991).
Tanaka, H., Takeuchi, T. & Ward, W. R. Three-dimensional interaction between a planet and an isothermal gaseous disk. I. Corotation and Lindblad torques and planet migration. Astrophys. J. 565, 1257–1274 (2002).
This study was supported by MEXT ‘Exploratory Challenge on Post-K computer’ (hp180183 and hp190143), by ‘Priority Issue on post-K computer’ (hp190156), by JSPS KAKENHI 15H02065 and 19K03950, and by MEXT KAKENHI 18H05438. The N-body simulation in this work was carried out at the Yukawa Institute Computer Facility.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Ida, S., Ueta, S., Sasaki, T. et al. Uranian satellite formation by evolution of a water vapour disk generated by a giant impact. Nat Astron 4, 880–885 (2020). https://doi.org/10.1038/s41550-020-1049-8
The Planetary Science Journal (2021)
Monthly Notices of the Royal Astronomical Society (2021)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences (2020)