Letter | Published:

The common origin of family and non-family asteroids

Nature Astronomyvolume 2pages549554 (2018) | Download Citation


All asteroids are currently classified as either family, originating from the disruption of known bodies1, or non-family. An outstanding question is the origin of these non-family asteroids. Were they formed individually, or as members of known families but with chaotically evolving orbits, or are they members of old ghost families, that is, asteroids with a common parent body but with orbits that no longer cluster in orbital element space? Here, we show that the sizes of the non-family asteroids in the inner belt are correlated with their orbital eccentricities and anticorrelated with their inclinations, suggesting that both non-family and family asteroids originate from a small number of large primordial planetesimals. We estimate that ~85% of the asteroids in the inner main belt originate from the Flora, Vesta, Nysa, Polana and Eulalia families, with the remaining ~15% originating from either the same families or, more likely, a few ghost families. These new results imply that we must seek explanations for the differing characteristics of the various meteorite groups in the evolutionary histories of a few, large, precursor bodies2. Our findings also support the model that asteroids formed big through the gravitational collapse of material in a protoplanetary disk3.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from $8.99

All prices are NET prices.

Additional information

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


  1. 1.

    Hirayama, K. Groups of asteroids probably of common origin. Astron. J. 31, 185–188 (1918).

  2. 2.

    Burbine, T. H., McCoy, T. J., Meibom, A., Gladman, B. & Keil, K. in Asteroids III (eds Bottke, W. F. Jr et al.) 653–667 (Univ. Arizona Press, Tucson, 2002).

  3. 3.

    Johansen, A. et al. Rapid planetesimal formation in turbulent circumstellar disks. Nature 448, 1022–1025 (2007).

  4. 4.

    Knežević, Z. & Milani, A. Synthetic proper elements for outer main belt asteroids. Celest. Mech. Dyn. Astr. 78, 17–46 (2000).

  5. 5.

    Nesvorný, D. Nesvorný HCM Asteroid Families V3.0. EAR-A-VARGBDET-5-NESVORNYFAM-V3.0 (NASA Planetary Data System, 2015).

  6. 6.

    Nesvorný, D., Broz, M. & Carrruba, V. in Asteroids IV (eds Michel, P. et al.) 297–321 (Univ. Arizona Press, Tucson, 2015).

  7. 7.

    Zappala, V., Cellino, A., Farinella, P. & Knežević, Z. Asteroid families. I. Identification by hierarchical clustering and reliability assessment. Astron. J. 100, 2030–2046 (1990).

  8. 8.

    Parker, A. et al. The size distributions of asteroid families in the SDSS Moving Object Catalog 4. Icarus 198, 138–155 (2008).

  9. 9.

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

  10. 10.

    Bottke, W. F., Vokrouhlický, D., Rubincam, D. P. & Broz, M. in Asteroids III (eds Bottke, W. F. Jr et al.) 395–408 (Univ. Arizona Press, Tucson, 2002).

  11. 11.

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

  12. 12.

    Dohnanyi, J. S. Collisional model of asteroids and their debris. J. Geophys. R. 74, 2531–2554 (1969).

  13. 13.

    Durda, D. D. & Dermott, S. F. The collisional evolution of the asteroid belt and its contribution to the zodiacal cloud. Icarus 130, 140–164 (1997).

  14. 14.

    Vokrouhlický, D. & Farinella, P. Efficient delivery of meteorites to the Earth from a wide range of asteroid parent bodies. Nature 407, 606–608 (2000).

  15. 15.

    Bottke, W. F., Rubincam, D. P. & Burns, J. A. Dynamical evolution of main belt meteoroids: numerical simulations incorporating planetary perturbations and Yarkovsky thermal forces. Icarus 145, 301–331 (2000).

  16. 16.

    Jacobson, S. A., Marzari, F., Rossi, A., Scheeres, D. J. & Davis, D. R. Effect of rotational disruption on the size-frequency distribution of the main belt asteroid population. Mon. Not. R. Astron. Soc. 439, L95–L99 (2014).

  17. 17.

    Morbidelli, A. & Nesvorný, D. Numerous weak resonances drive asteroids toward terrestrial planet’s orbits. Icarus 139, 295–308 (1999).

  18. 18.

    Minton, D. A. & Malhotra, R. Dynamical erosion of the asteroid belt and implications for large impacts in the inner Solar System. Icarus 207, 744–757 (2010).

  19. 19.

    Delbo', M., Walsh, K., Avdellidou, C., Morbidelli, M. Identification of a primordial asteroid family constrains the original planetesimal population. Science 357, 1026–1029 (2017).

  20. 20.

    Milani, A. & Nobili, A. Integration error over a very long time span. Celest. Mech. Dyn. Astr. 43, 1–34 (1988).

  21. 21.

    The OrbFit Software Package (The OrbFit Consortium); http://adams.dm.unipi.it/orbfit/

  22. 22.

    Carruba, V.,Burns, J. A., Bottke, W. & Nesvorný, D. Orbital evolution of the Gefion and Adeona asteroid families: Close encounters with massive asteroids and the Yarkovsky effect. Icarus 162, 308–327 (2003).

  23. 23.

    Murray, C. D. & Dermott, S. F. Solar System Dynamics (Cambridge Univ. Press, Cambridge, 1999).

  24. 24.

    Fisher, R. A. Statistical Methods for Research Workers 14th edn (Hafner, Darien, 1970).

  25. 25.

    Masiero, J. R. et al. Asteroid family identification using the Hierarchical Clustering Method and WISE/NEOWISE physical properties. Astrophys. J. 770, 7–29 (2013).

Download references


A.A.C. thanks Z. Knežević for his advice on using ORBIT9 and on generating proper elements, and acknowledges the SFI/HEA Irish Centre for High-End Computing (ICHEC) for the provision of computational facilities and support. Astronomical research at the Armagh Observatory and Planetarium is funded by the Northern Ireland Department of Communities (DfC).

Author information

Author notes

    • Dan Li

    Present address: National Optical Astronomy Observatory, Tucson, AZ, USA


  1. Department of Astronomy, University of Florida, Gainesville, FL, USA

    • Stanley F. Dermott
    •  & J. Malcolm Robinson
  2. Armagh Observatory and Planetarium, Armagh, UK

    • Apostolos A. Christou
  3. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA

    • Dan Li
  4. Florida Space Institute, Orlando, FL, USA

    • Thomas. J. J. Kehoe


  1. Search for Stanley F. Dermott in:

  2. Search for Apostolos A. Christou in:

  3. Search for Dan Li in:

  4. Search for Thomas. J. J. Kehoe in:

  5. Search for J. Malcolm Robinson in:


S.F.D. initiated and directed the research and wrote the paper. A.A.C. performed the numerical investigations of chaotic orbital evolution and wrote the corresponding part of the Methods. D.L., T.J.J.K. and J.M.R. contributed to the data analysis.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Stanley F. Dermott.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–5, Supplementary Tables 1–2

About this article

Publication history