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.

The population of rotational fission clusters inside asteroid collisional families


Asteroid families are groups of objects sharing similar orbits. They are mostly the results of past collisions between two asteroids. Recent studies have shown that some asteroid families can also be the outcome of the spin-up-induced fission of a critically rotating parent body (fission clusters). In at least four young fission clusters, more than 5% of their members belong to subfamilies, secondary clusters of objects mostly formed after the main fission event. However, asteroidal subfamilies are still not well characterized. In this work, using family recognition methods based on time-reversal dynamical simulations, machine-learning clustering algorithms and the exceptional orbit accuracy obtained from Gaia observations of Solar System objects, we identify several subclusters within four extremely young collisional families. We find that collisional asteroid families younger than 100 Myr have a higher fraction of young detectable fission subclusters with respect to older groups. The collisional events that form asteroid families may trigger a subsequent cascade of spin-induced formations of fission clusters by producing fragments in highly rotating states.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Orbital locations of the secondary and tertiary clusters identified inside the (3152) Jones, (7353) Kazuya, (108138) 2001 GB11 and (5438) Lorre asteroid families.
Fig. 2: Locations of primary, secondary and tertiary groups in the plane of a dispersion versus cluster age.
Fig. 3: Fraction of members in secondary and tertiary groups as a function of the family age.

Data availability

The data that support the plots within this paper and other findings of this study either are available in the paper and in its supplementary tables, or are available from the corresponding author on reasonable request.

Code availability

The machine-learning codes used in this work are available in the GitHub repository under an MIT public license ( The source code for the symplectic integrator used for the numerical simulation of the asteroid orbits is part of the SWIFT package, which can be obtained at Any other codes or data presented in this paper can be obtained from the corresponding author on reasonable request.


  1. 1.

    Knežević, Z. & Milani, A. Proper element catalogs and asteroid families. Astron. Astrophys. 403, 1165–1173 (2003).

    ADS  Article  Google Scholar 

  2. 2.

    Bottke, W. F. Jr, Vokrouhlický, D., Rubincam, D. P. & Broz, M. in Asteroid III (eds Bottke, W. F. Jr, Cellino, A., Paolicchi, P. & Binzel, R. P.) 395–408 (Univ. of Arizona Press, 2003).

  3. 3.

    Walsh, K. J., Richardson, D. C. & Michel, P. Rotational breakup as the origin of small binary asteroids. Nature 454, 188–191 (2008).

    ADS  Article  Google Scholar 

  4. 4.

    Jacobson, S. A. & Scheeres, D. J. Dynamics of rotationally fissioned asteroids: source of observed small asteroid systems. Icarus 214, 161–178 (2011).

    ADS  Article  Google Scholar 

  5. 5.

    Vokrouhlický, D. et al. The young Datura asteroid family. Spins, shapes, and population estimate. Astron. Astrophys. 598, A91 (2017).

    Article  Google Scholar 

  6. 6.

    Pravec, P. et al. Formation of asteroid pairs by rotational fission. Nature 466, 1085–1088 (2010).

    ADS  Article  Google Scholar 

  7. 7.

    Nesvorný, D. & Vokrouhlický, D. New candidates for recent asteroid breakups. Astron. J. 132, 1950–1958 (2006).

    ADS  Article  Google Scholar 

  8. 8.

    Nesvorný, D., Vokrouhlicky, D. & Bottke, W. F. Jr. The breakup of a main-belt asteroid 450 thousand years ago. Science 312, 1490 (2006).

    ADS  Article  Google Scholar 

  9. 9.

    Vokrouhlický, D. & Nesvorný, D. Half-brothers in the Schulhof family? Astron. J. 142, A26 (2011).

    ADS  Article  Google Scholar 

  10. 10.

    Pravec, P. et al. Asteroid clusters similar to asteroid pairs. Icarus 304, 110–126 (2018).

    ADS  Article  Google Scholar 

  11. 11.

    Carruba, V., De Oliveira, E. R., Rodrigues, B. & Requena, I. The quest for young asteroid families: new families, new results. Mon. Not. R. Astron. Soc. 479, 4815–4823 (2018).

    ADS  Article  Google Scholar 

  12. 12.

    Novaković, B., Hsieh, H. H. & Cellino, A. P/2006 VW139: a main-belt comet born in an asteroid collision? Mon. Not. R. Astron. Soc. 424, 1432–1441 (2012).

    ADS  Article  Google Scholar 

  13. 13.

    Gaia Collaboration et al. Gaia data release 2. Observations of solar system objects. Astron. Astrophys. 616, A13 (2018).

    Article  Google Scholar 

  14. 14.

    Pedregosa, F. et al. Scikit-learn: machine learning in Python. J. Mach. Learn. Res. 12, 2825–2830 (2011).

    MathSciNet  MATH  Google Scholar 

  15. 15.

    Gaia Collaboration et al. Gaia data release 2: summary of the contents and survey properties. Astron. Astrophys. 616, A1 (2018).

    Article  Google Scholar 

  16. 16.

    Milani, A. et al. Asteroid families classification: exploiting very large datasets. Icarus 239, 46–73 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Milani, A., Spoto, F., Knežević, Z., Novaković, B. & Tsirvoulis, G. Families classification including multiopposition asteroids. IAU Symp. 318, 28–45 (2016).

    ADS  Google Scholar 

  18. 18.

    Nesvorný, D., Brož, M. & Carruba, V. in Asteroid IV (eds Michel, P., DeMeo, F. E. & Bottke, W.) 297–321 (Univ. of Arizona Press, 2015).

  19. 19.

    Bolin, B. T., Morbidelli, A. & Walsh, K. J. Size-dependent modification of asteroid family Yarkovsky V-shapes. Astron. Astrophys. 611, A82 (2018).

    ADS  Article  Google Scholar 

  20. 20.

    Milani, A., Knežević, Z., Spoto, F. & Paolicchi, P. Asteroid cratering families: recognition and collisional interpretation. Astron. Astrophys. 622, A47 (2018).

    Article  Google Scholar 

  21. 21.

    Milani, A. & Gronchi, G. F. Theory of Orbit Determination (Cambridge University Press, 2010).

  22. 22.

    Spoto, F., Milani, A. & Knežević, Z. Asteroid family ages. Icarus 257, 275–289 (2015).

    ADS  Article  Google Scholar 

  23. 23.

    Levison, H. F. & Duncan, M. J. The long-term dynamical behavior of short-period comets. Icarus 108, 18–36 (1994).

    ADS  Article  Google Scholar 

  24. 24.

    Nesvorný, D., Bottke, W. F. Jr, Dones, L. & Levison, H. F. The recent breakup of an asteroid in the main-belt region. Nature 417, 720–771 (2002).

    ADS  Article  Google Scholar 

  25. 25.

    Nesvorný, D. & Bottke, W. F. Jr. Detection of the Yarkovsky effect for main-belt asteroids. Icarus 170, 324–342 (2004).

    ADS  Article  Google Scholar 

  26. 26.

    Hareyama, M. et al. Global classification of lunar reflectance spectra obtained by Kaguya (SELENE): implication for hidden basaltic materials. Icarus 321, 407–425 (2019).

    ADS  Article  Google Scholar 

  27. 27.

    Zappalá, V., Cellino, A., Farinella, P. & Knezevic, Z. Asteroid families. I—identification by hierarchical clustering and reliability assessment. Astron. J. 100, 2030–2046 (1990).

    ADS  Article  Google Scholar 

Download references


We would like to thank the São Paulo State Science Foundation (FAPESP), which supported this work via grant 18/20999-6, and the Brazilian National Research Council (CNPq, grants 301577/2017-0, 153683/2018-0). The work of F.S. is supported by the CNES fellowship research programme. We are grateful for useful discussion with E. R. De Oliveira on the use of machine-learning algorithms in dynamical astronomy, to D. Nesvorný and O. Winter for comments on a revised version of this manuscript and to D. Vokrouhlický for many helpful discussions on young asteroid families. We also thank AstDyS (, ref. 1) for the use of data. This publication also makes use of data products from the Wide-field Infrared Survey Explorer (WISE) and Near-Earth Objects (NEOWISE), which are a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This work used data from the European Space Agency mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Finally, this research has also made use of data and/or services provided by the International Astronomical Union’s Minor Planet Center.

Author information




V.C. initiated and directed the research and wrote the paper. F.S., W.B., S.A., Á.L.F. and B.M. all contributed to the data analysis and to the revision of the paper. F.S. processed the astrometric data from Gaia observations. S.A. was responsible for the format of the LaTeX files of the article.

Corresponding author

Correspondence to V. Carruba.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Astronomy thanks Apostolos Christou and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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

Supplementary information

Supplementary information

Supplementary Tables 1–9, Figs. 1–14, text and references.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Carruba, V., Spoto, F., Barletta, W. et al. The population of rotational fission clusters inside asteroid collisional families. Nat Astron 4, 83–88 (2020).

Download citation


Quick links