The Juno mission1 has provided an accurate determination of Jupiter’s gravitational field2, which has been used to obtain information about the planet’s composition and internal structure. Several models of Jupiter’s structure that fit the probe’s data suggest that the planet has a diluted core, with a total heavy-element mass ranging from ten to a few tens of Earth masses (about 5 to 15 per cent of the Jovian mass), and that heavy elements (elements other than hydrogen and helium) are distributed within a region extending to nearly half of Jupiter’s radius3,4. Planet-formation models indicate that most heavy elements are accreted during the early stages of a planet's formation to create a relatively compact core5,6,7 and that almost no solids are accreted during subsequent runaway gas accretion8,9,10. Jupiter’s diluted core, combined with its possible high heavy-element enrichment, thus challenges standard planet-formation theory. A possible explanation is erosion of the initially compact heavy-element core, but the efficiency of such erosion is uncertain and depends on both the immiscibility of heavy materials in metallic hydrogen and on convective mixing as the planet evolves11,12. Another mechanism that can explain this structure is planetesimal enrichment and vaporization13,14,15 during the formation process, although relevant models typically cannot produce an extended diluted core. Here we show that a sufficiently energetic head-on collision (giant impact) between a large planetary embryo and the proto-Jupiter could have shattered its primordial compact core and mixed the heavy elements with the inner envelope. Models of such a scenario lead to an internal structure that is consistent with a diluted core, persisting over billions of years. We suggest that collisions were common in the young Solar system and that a similar event may have also occurred for Saturn, contributing to the structural differences between Jupiter and Saturn16,17,18.
This is a preview of subscription content, access via your institution
Open Access articles citing this article.
Computational Astrophysics and Cosmology Open Access 02 December 2020
Nature Communications Open Access 25 March 2020
Subscribe to Nature+
Get immediate online access to Nature and 55 other Nature journal
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The datasets generated and analysed during the current study are available from the corresponding authors upon reasonable request.
The FLASH code is publicly available for download at http://flash.uchicago.edu/site/flashcode. The implementation of giant impact simulations in the framework of FLASH is available upon request. The REBOUND code is publicly available for download at https://github.com/hannorein/rebound. The MESA code is an open source stellar evolution code and is publicly available at http://mesa.sourceforge.net. The modified version of the MESA code is not yet ready for public release—it will be presented in future work (S.M., A. Cumming & R.H.; manuscript in preparation). Gnuplot, Jupyter Notebook, Mathematica, VisIt and yt python packages were used for data reduction and presentation in this study.
Bolton, S. J. et al. The Juno mission. Space Sci. Rev. 213, 5–37 (2017).
Folkner, W. M. et al. Jupiter gravity field estimated from the first two Juno orbits. Geophys. Res. Lett. 44, 4694–4700 (2017).
Wahl, S. M. et al. Comparing Jupiter interior structure models to Juno gravity measurements and the role of a dilute core. Geophys. Res. Lett. 44, 4649–4659 (2017).
Debras, F. & Chabrier, G. New models of Jupiter in the context of Juno and Galileo. Astrophys. J. 872, 100 (2019).
Pollack, J. B. et al. Formation of the giant planets by concurrent accretion of solids and gas. Icarus 124, 62–85 (1996).
Ikoma, M., Nakazawa, K. & Emori, H. Formation of giant planets: dependences on core accretion rate and grain opacity. Astrophys. J. 537, 1013–1025 (2000).
Helled, R. et al. Giant planet formation, evolution, and internal structure. Protostars Planets VI, 643 (2014).
Paardekooper, S.-J. & Mellema, G. Planets opening dust gaps in gas disks. Astron. Astrophys. 425, L9–L12 (2004).
Levison, H. F., Thommes, E. & Duncan, M. J. Modeling the formation of giant planet cores. i. evaluating key processes. Astron. J. 139, 1297–1314 (2010).
Bitsch, B. et al. Pebble-isolation mass: scaling law and implications for the formation of super-Earths and gas giants. Astron. Astrophys. 612, A30 (2018).
Guillot, T., Stevenson, D. J., Hubbard, W. B. & Saumon, D. The interior of Jupiter. In Jupiter: The Planet, Satellites and Magnetosphere 35–57 (Cambridge Univ. Press, 2004).
Wilson, H. F. & Militzer, B. Solubility of water ice in metallic hydrogen: consequences for core erosion in gas giant planets. Astrophys. J. 745, 54 (2012).
Stevenson, D. J. Structure of the giant planets: evidence for nucleated instabilities and post-formational accretion. Lunar Planet. Sci. Conf. 13, 770–771 (1982).
Hori, Y. & Ikoma, M. Gas giant formation with small cores triggered by envelope pollution by icy planetesimals. Mon. Not. R. Astron. Soc. 416, 1419–1429 (2011).
Lozovsky, M., Helled, R., Rosenberg, E. D. & Bodenheimer, P. Jupiter’s formation and its primordial internal structure. Astrophys. J. 836, 227 (2017).
Guillot, T. The interiors of giant planets: models and outstanding questions. Annu. Rev. Earth Planet. Sci. 33, 493–530 (2005).
Nettelmann, N., Becker, A., Holst, B. & Redmer, R. Jupiter models with improved ab initio hydrogen equation of state (H-REOS.2). Astrophys. J. 750, 52 (2012).
Helled, R. & Guillot, T. Interior models of Saturn: including the uncertainties in shape and rotation. Astrophys. J. 767, 113 (2013).
Li, S.-L., Agnor, C. & Lin, D. N. C. Embryo impacts and gas giant mergers. I. Dichotomy of Jupiter and Saturn’s core mass. Astrophys. J. 720, 1161–1173 (2010).
Liu, S.-F., Agnor, C. B., Lin, D. N. C. & Li, S.-L. Embryo impacts and gas giant mergers—II. Diversity of hot Jupiters’ internal structure. Mon. Not. R. Astron. Soc. 446, 1685–1702 (2015).
Kokubo, E. & Ida, S. Oligarchic growth of protoplanets. Icarus 131, 171–178 (1998).
Ida, S. & Lin, D. N. C. Toward a deterministic model of planetary formation. I. A desert in the mass and semimajor axis distributions of extrasolar planets. Astrophys. J. 604, 388–413 (2004).
Zhou, J.-L. & Lin, D. N. C. Planetesimal accretion onto growing proto-gas giant planets. Astrophys. J. 666, 447–465 (2007).
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).
Fryxell, B. et al. FLASH: an adaptive mesh hydrodynamics code for modeling astrophysical thermonuclear flashes. Astrophys. J. Suppl. 131, 273–334 (2000).
Berardo, D. & Cumming, A. Hot-start giant planets form with radiative interiors. Astrophys. J. 846, L17 (2017).
Cumming, A., Helled, R. & Venturini, J. The primordial entropy of Jupiter. Mon. Not. R. Astron. Soc. 477, 4817–4823 (2018).
Helled, R. & Stevenson, D. The fuzziness of giant planets’ cores. Astrophys. J. 840, L4 (2017).
Thorngren, D. P. & Fortney, J. J. Bayesian analysis of hot-Jupiter radius anomalies: evidence for ohmic dissipation? Astron. J. 155, 214 (2018).
Rein, H. & Liu, S.-F. REBOUND: an open-source multi-purpose N-body code for collisional dynamics. Astron. Astrophys. 537, A128 (2012).
Rein, H. & Tamayo, D. WHFAST: a fast and unbiased implementation of a symplectic Wisdom–Holman integrator for long-term gravitational simulations. Mon. Not. R. Astron. Soc. 452, 376–388 (2015).
Rein, H. & Spiegel, D. S. IAS15: a fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits. Mon. Not. R. Astron. Soc. 446, 1424–1437 (2015).
Asphaug, E., Agnor, C. B. & Williams, Q. Hit-and-run planetary collisions. Nature 439, 155–160 (2006).
Lin, D. N. C. & Ida, S. On the origin of massive eccentric planets. Astrophys. J. 477, 781–791 (1997).
Izidoro, A., Raymond, S. N., Morbidelli, A., Hersant, F. & Pierens, A. Gas giant planets as dynamical barriers to inward-migrating super-Earths. Astrophys. J. 800, L22 (2015).
Izidoro, A., Morbidelli, A., Raymond, S. N., Hersant, F. & Pierens, A. Accretion of Uranus and Neptune from inward-migrating planetary embryos blocked by Jupiter and Saturn. Astron. Astrophys. 582, A99 (2015).
Liu, S.-F., Hori, Y., Lin, D. N. C. & Asphaug, E. Giant impact: an efficient mechanism for the devolatilization of super-Earths. Astrophys. J. 812, 164 (2015).
Melosh, H. J. Impact Cratering: A Geologic Process (Oxford Univ. Press, 1989).
Liu, S.-F., Guillochon, J., Lin, D. N. C. & Ramirez-Ruiz, E. On the survivability and metamorphism of tidally disrupted giant planets: the role of dense cores. Astrophys. J. 762, 37 (2013).
Paxton, B. et al. Modules for Experiments in Stellar Astrophysics (MESA). Astrophys. J. Suppl. 192, 1–110 (2011).
Paxton, B. et al. Modules for experiments in stellar astrophysics (MESA): planets, oscillations, rotation, and massive stars. Astrophys. J. Suppl. 208, 4 (2013).
Paxton, B. et al. Modules for Experiments in Stellar Astrophysics (MESA): binaries, pulsations, and explosions. Astrophys. J. Suppl. 220, 1–43 (2015).
Paxton, B. et al. Modules for Experiments in Stellar Astrophysics (MESA): convective boundaries, element diffusion, and massive star explosions. Astrophys. J. Suppl. 234, 34 (2018).
Saumon, D., Chabrier, G. & van Horn, H. M. An equation of state for low-mass stars and giant planets. Astrophys. J. Suppl. 99, 713 (1995).
More, R. M., Warren, K. H., Young, D. A. & Zimmerman, G. B. A new quotidian equation of state (QEOS) for hot dense matter. Phys. Fluids 31, 3059–3078 (1988).
Vazan, A., Kovetz, A., Podolak, M. & Helled, R. The effect of composition on the evolution of giant and intermediate-mass planets. Mon. Not. R. Astron. Soc. 434, 3283–3292 (2013).
Cassisi, S., Potekhin, A. Y., Pietrinferni, A., Catelan, M. & Salaris, M. Updated electron-conduction opacities: the impact on low-mass stellar models. Astrophys. J. 661, 1094–1104 (2007).
Freedman, R. S., Marley, M. S. & Lodders, K. Line and mean opacities for ultracool dwarfs and extrasolar planets. Astrophys. J. Suppl. 174, 504–513 (2008).
Ledoux, W. P. Stellar models with convection and with discontinuity of the mean molecular weight. Astrophys. J. 105, 305 (1947).
Rosenblum, E., Garaud, P., Traxler, A. & Stellmach, S. Turbulent mixing and layer formation in double-diffusive convection: three-dimensional numerical simulations and theory. Astrophys. J. 731, 66 (2011).
Vazan, A., Helled, R. & Guillot, T. Jupiter’s evolution with primordial composition gradients. Astron. Astrophys. 610, L14 (2018).
Langer, N., Sugimoto, D. & Fricke, K. J. Semiconvective diffusion and energy transport. Astron. Astrophys. 126, 207–208 (1983).
Wood, T. S., Garaud, P. & Stellmach, S. A new model for mixing by double-diffusive convection (semi-convection). II. The transport of heat and composition through layers. Astrophys. J. 768, 157 (2013).
Radko, T. et al. Double-diffusive recipes. Part I: Large-scale dynamics of thermohaline staircases. J. Phys. Oceanogr. 44, 1269–1284 (2014).
Leconte, J. & Chabrier, G. A new vision of giant planet interiors: impact of double diffusive convection. Astron. Astrophys. 540, A20 (2012).
Baraffe, I., Chabrier, G., Fortney, J. J. & Sotin, C. Planetary internal structures. Protostars Planets VI, 763–786 (2014).
We thank S. M. Wahl and Y. Miguel for sharing their results with us. We thank A. Cumming for technical support and discussions. We thank J. J. Fortney, P. Garaud and H. Rein for conversations. S.-F.L. acknowledges the support and hospitality provided by the Aspen Center for Physics during the early stage of this work. D.L. thanks the Institute for Advanced Study, Princeton, the Institute of Astronomy and Department of Applied Mathematics and Theoretical Physics, Cambridge University, for support and hospitality while this work was being completed. R.H. acknowledges support from SNSF grant number 200021_169054. A.I. acknowledges support from the National Aeronautics and Space Administration under award number 80NSSC18K0828 and from the National Science Foundation under grant number AST-1715719.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
Extended Data Fig. 1 Statistics of outcomes of four planetary embryos under the influence of an emerging Jupiter.
a, The initial configurations of four planetary embryos divided into four groups based on the fixed parameters shown under the group numbers. In groups 1–3, half of the embryos are placed inside Jupiter’s orbit (labelled ‘Inward’); the other half are outside Jupiter’s orbit (labelled ‘Outward’). In group 4, all embryos are outside Jupiter’s orbit. The exact location of every embryo is shown in Extended Data Table 1. b, The statistical outcomes of the dynamic evolution after 10tgrow. Jupiter’s growth can substantially modify the orbits of those embryos. Some embryos collided with Jupiter (labelled ‘Merge’), and some have been ejected from the Solar System (labelled ‘Escape’). Colours indicate different choices of the free parameters (inflation factor f and orbital separation factor k; see methods section ‘A statistical N-body study of embryo collisions’) as shown for each group. The height of each bar (‘Frac’) indicates the percentage of each state.
Extended Data Fig. 2 Histograms of collision angles of each dataset presented in Extended Data Fig. 1.
a, Group 1; b, group 2; c, group 3; d, group 4. The bin size is 5°, and there are 18 bins in each plot. The collision angle is measured in degrees. The red dashed line indicates the median value in each case. The results suggest that head-on collisions are more common (greater percentage probability) than grazing collisions. Each case has a different N, but they all fall in the range between 1,000 to 1,500.
Extended Data Fig. 3 Two-dimensional snapshots of a merger between the proto-Jupiter with a 10M⊕ rock/ice core and a 10M⊕ impactor.
a, Density contours in the orbital plane before the impact; b, before the impactor arriving at the core; c, after the destruction of the core; d, at about 10 h after the impact. Time in each panel is measured since the start of the simulation.
Extended Data Fig. 4 The change of internal energy caused by the merger between the proto-Jupiter with a 10M⊕ rock/ice core and a 10M⊕ impactor.
a, The enclosed internal energy Einternal of Jupiter before and after the impact as a function of radius. b, The net change of enclosed internal energy ΔEinternal of Jupiter as a function of radius.
Extended Data Fig. 5 Two-dimensional snapshots of a merger between the proto-Jupiter with a 17M⊕ core and a 1M⊕ impactor.
a, Density contours in the orbital plane before the impact; b, before the impactor arriving at the core; c, after the merger with the core; d, at about 10 h after the impact. Time in each panel is measured since the start of the simulation.
a, The initial post-impact heavy-element profile; b, temperature profiles of the models used for the thermal evolution. The heavy-element distribution is taken from the hydro-simulation 10 h after the giant impact. Solid lines correspond to a head-on collision, while dashed-dotted lines show the result of an oblique collision at a 45° angle. The colours depict models with different initial thermal states. See text and Extended Data Table 2 for further details. The radius is normalized by the present-day radius of Jupiter RJ.
Extended Data Fig. 7 Density versus normalized radius for the head-on collision after 4.56 Gyr of evolution.
The colours correspond to distinct model assumptions: models H-4.3, H-4.5 and H-4.7 correspond to initial thermal profiles with different central temperatures at the time of the impact, whereas model H-radenv assumes a proto-Jupiter with a radiative envelope. Model H-4.5-lowα uses a shorter mixing length, model H-4.5-semiconv allows for semi-convective mixing, and in model H-4.5-rock the heavy elements are represented by rock instead of water for EOS purposes. The inset zooms in on the region with a normalized radius between 0.15 and 0.5. See text and Extended Data Table 2 for further details.
Extended Data Fig. 8 Density versus normalized radius for the oblique collision after 4.56 Gyr of evolution.
The colours correspond to distinct model assumptions: models O-4.3, O-4.5 and O-4.7 correspond to initial thermal profiles with different central temperatures at the time of the impact. Model O-4.5-lowα uses a shorter mixing length, model O-4.5-semiconv allows for semi-convective mixing, and in model O-4.5-rock the heavy elements are represented by rock instead of water for EOS purposes. The inset zooms in on the region with a normalized radius between 0.15 and 0.4. See text and Extended Data Table 2 for further details.
3D cutaway animation of consequence of a head-on collision between a proto-Jupiter and a massive planetary embryo. Snapshots of the animation are presented in Figure 1 in the main text.
2D animation of the density contours of a head-on collision between a proto-Jupiter and a massive planetary embryo. Snapshots of the animation are presented in Extended Data Figure 3.
2D animation of the density contours of an oblique collision between a proto-Jupiter and a massive planetary embryo. Snapshots of the animation are presented in Figure 3.
2D animation of the density contours of a head-on collision between a proto-Jupiter with a massive core and a small planetary embryo. Snapshots of the animation are presented in Extended Data Figure 5.
Animation of the evolution of temperature, density, specific entropy and heavy-element mass fraction of model H-4.5 over 4.5 Gyr. At the end of the simulation, a diluted core is formed. See Methods for details.
Animation of the evolution of temperature, density, specific entropy and heavy-element mass fraction of model H-4.5-semiconv over 4.5 Gyr. At the end of the simulation, a diluted core is formed. See Methods for details.
Animation of the evolution of temperature, density, specific entropy and heavy-element mass fraction of model H-4.7 over 4.5 Gyr. At the end of the simulation, the compositional gradient established after the impact disappears due to a very hot interior. See Methods for details.
About this article
Cite this article
Liu, SF., Hori, Y., Müller, S. et al. The formation of Jupiter’s diluted core by a giant impact. Nature 572, 355–357 (2019). https://doi.org/10.1038/s41586-019-1470-2
This article is cited by
Nature Astronomy (2021)
Computational Astrophysics and Cosmology (2020)
Nature Communications (2020)
Space Science Reviews (2020)