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A nearby neutron-star merger explains the actinide abundances in the early Solar System


A growing body of evidence indicates that binary neutron-star mergers are the primary origin of heavy elements produced exclusively through rapid neutron capture1,2,3,4 (the ‘r-process’). As neutron-star mergers occur infrequently, their deposition of radioactive isotopes into the pre-solar nebula could have been dominated by a few nearby events. Although short-lived r-process isotopes—with half-lives shorter than 100 million years—are no longer present in the Solar System, their abundances in the early Solar System are known because their daughter products were preserved in high-temperature condensates found in meteorites5. Here we report that abundances of short-lived r-process isotopes in the early Solar System point to their origin in neutron-star mergers, and indicate substantial deposition by a single nearby merger event. By comparing numerical simulations with the early Solar System abundance ratios of actinides produced exclusively through the r-process, we constrain the rate of occurrence of their Galactic production sites to within about 1−100 per million years. This is consistent with observational estimates of neutron-star merger rates6,7,8, but rules out supernovae and stellar sources. We further find that there was probably a single nearby merger that produced much of the curium and a substantial fraction of the plutonium present in the early Solar System. Such an event may have occurred about 300 parsecs away from the pre-solar nebula, approximately 80 million years before the formation of the Solar System.

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Data availability

The datasets generated during and/or analysed during the current study are available in the Zenodo repository, https://doi.org/10.5281/zenodo.2556447. Source Data for Figs. 2 and 3 are provided with the paper.

Code availability

The computer code that was used for the calculations is available from the corresponding author upon reasonable request.

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  1. 1.

    Goriely, S., Bauswein, A. & Janka, H.-T. r-process nucleosynthesis in dynamically ejected matter of neutron star mergers. Astrophys. J. 738, L32 (2011).

  2. 2.

    Abbott, B. P. et al. Multi-messenger observations of a binary neutron star merger. Astrophys. J. 848, L12 (2017).

  3. 3.

    Hotokezaka, K., Piran, T. & Paul, M. Short-lived 244Pu points to compact binary mergers as sites for heavy r-process nucleosynthesis. Nat. Phys. 11, 1042 (2015).

  4. 4.

    Côté, B. et al. The origin of r-process elements in the Milky Way. Astrophys. J. 855, 99 (2018).

  5. 5.

    Tissot, F. L. H., Dauphas, N. & Grossman, L. Origin of uranium isotope variations in early solar nebula condensates. Sci. Adv. 2, e1501400 (2016).

  6. 6.

    Wanderman, D. & Piran, T. The rate, luminosity function and time delay of non-collapsar short GRBs. Mon. Not. R. Astron. Soc. 448, 3026–3037 (2015).

  7. 7.

    Abbott, B. P. et al. GWTC-1: a gravitational-wave transient catalog of compact binary mergers observed by LIGO and Virgo during the first and second observing runs. Preprint at http://arxiv.org/abs/1811.12907 (2018).

  8. 8.

    Gupte, N. & Bartos, I. Observational consequences of structured jets from neutron star mergers in the local Universe. Preprint at http://arxiv.org/abs/1808.06238 (2018).

  9. 9.

    Abadie, J. et al. Topical review: predictions for the rates of compact binary coalescences observable by ground-based gravitational-wave detectors. Class. Quantum Gravity 27, 173001 (2010).

  10. 10.

    Wasserburg, G. J., Busso, M., Gallino, R. & Nollett, K. M. Short-lived nuclei in the early Solar System: possible AGB sources. Nucl. Phys. A 777, 5–69 (2006).

  11. 11.

    McMillan, P. J. Mass models of the Milky Way. Mon. Not. R. Astron. Soc. 414, 2446–2457 (2011).

  12. 12.

    Montmerle, T. et al. 3. Solar System formation and early evolution: the first 100 million years. Earth Moon Planets 98, 39–95 (2006).

  13. 13.

    Tang, H., Liu, M.-C., McKeegan, K. D., Tissot, F. L. H. & Dauphas, N. In situ isotopic studies of the U-depleted Allende CAI Curious Marie: pre-accretionary alteration and the co-existence of 26Al and 36Cl in the early solar nebula. Geochim. Cosmochim. Acta 207, 1–18 (2017).

  14. 14.

    Dauphas, N. & Chaussidon, M. A perspective from extinct radionuclides on a young stellar object: the Sun and its accretion disk. Annu. Rev. Earth Planet. Sci. 39, 351–386 (2011).

  15. 15.

    Cappellaro, E., Evans, R. & Turatto, M. A new determination of supernova rates and a comparison with indicators for galactic star formation. Astron. Astrophys. 351, 459–466 (1999).

  16. 16.

    Lugaro, M., Ott, U. & Kereszturi, A. Radioactive nuclei from cosmochronology to habitability. Prog. Part. Nucl. Phys. 102, 1–47 (2018).

  17. 17.

    Kopparapu, R. K. et al. Host galaxies catalog used in LIGO searches for compact binary coalescence events. Astrophys. J. 675, 1459–1467 (2008).

  18. 18.

    Fong, W., Berger, E., Margutti, R. & Zauderer, B. A. A decade of short-duration gamma-ray burst broadband afterglows: energetics, circumburst densities, and jet opening angles. Astrophys. J. 815, 102 (2015).

  19. 19.

    Berger, E. Short-duration gamma-ray bursts. Annu. Rev. Astron. Astrophys. 52, 43–105 (2014).

  20. 20.

    Siegel, D. M., Barnes, J. & Metzger, B. D. The neutron star merger GW170817 points to collapsars as the main r-process source. Preprint at http://arxiv.org/abs/1810.00098 (2018).

  21. 21.

    Tauris, T. M. & van den Heuvel, E. P. J. in Compact Stellar X-ray Sources (eds Lewin, W. & van der Klis, M.) 623–665 (Cambridge Univ. Press, Cambridge, 2006).

  22. 22.

    Metzger, B. D. Kilonovae. Living Rev. Relativ. 20, 3 (2017).

  23. 23.

    Cowperthwaite, P. S. et al. The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. II. UV, optical, and near-infrared light curves and comparison to kilonova models. Astrophys. J. 848, L17 (2017).

  24. 24.

    Truran, J. W. The age of the universe from nuclear chronometers. Proc. Natl Acad. Sci. USA 95, 18–21 (1998).

  25. 25.

    Yang, C.-C. & Krumholz, M. Thermal-instability-driven turbulent mixing in galactic disks. I. Effective mixing of metals. Astrophys. J. 758, 48 (2012).

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We are grateful to S. Goldstein, D. Helfand, T. Huard, Z. Marka, P. Mueller, C. Scharf and W. Zajc for their valuable comments and suggestions. We also thank the University of Florida and Columbia University in the City of New York for their generous support.

Author information

I.B. and S.M. contributed to the origination of the idea for the project and worked out the general details collaboratively. I.B. carried out the calculations.

Competing interests

The authors declare no competing interests.

Correspondence to Imre Bartos.

Extended data tables

  1. Extended Data Table 1 Abundance ratios of r-process isotopes

Source data

  1. Source Data Fig. 2

  2. Source Data Fig. 3

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Fig. 1: The path of r-process elements.
Fig. 2: Simulated r-process abundance ratio near the pre-solar nebula.
Fig. 3: Simulated abundance ratios for multiple r-process isotopes.


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