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Rapid formation of exoplanetesimals revealed by white dwarfs

Nature Astronomy volume 7, pages 39–48 (2023)Cite this article

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Abstract

The timing of formation of the first planetesimals determines the mode of planetary accretion and their geophysical and compositional evolution. Astronomical observations of circumstellar disks and Solar System geochronology provide evidence for planetesimal formation during molecular cloud collapse, much earlier than previously estimated. Here we present distinct observational evidence from white dwarf planetary systems for planetesimal formation occurring during the first few hundred thousand years after cloud collapse in exoplanetary systems. A substantial fraction of white dwarfs have accreted planetary material rich in iron core or mantle material. For the exo-asteroids accreted by white dwarfs to form iron cores, substantial heating is required. By simulating planetesimal evolution and collisional evolution, we show that the most likely heat source is short-lived radioactive nuclides such as 26Al (which has a half-life of ~0.7 Myr). Core-rich materials in the atmospheres of white dwarfs, therefore, provide independent evidence for rapid planetesimal formation, concurrent with star formation.

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Fig. 1: Enrichment in Fe, Ni and Cr relative to Ca, Mg and Si of planetary materials accreted by white dwarfs suggests the accretion of core- or mantle-rich material.
Fig. 2: Almost all planetesimals that undergo core–mantle differentiation form within the Class 0/I collapse phase in exoplanetary systems with plausible levels of 26Al enrichment.
Fig. 3: The core- or mantle-rich materials in the atmospheres of white dwarfs are the collision fragments of planetesimals that formed earlier than ~1 Myr, when large-scale melting was fuelled by the decay of 26Al.
Fig. 4: Plutos can be the source of core-rich planetesimal debris only in rare (<1%) white dwarf systems with massive, close-in planetesimal belts.

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Data availability

The data used to create Figs. 1–4 are available in the Supplementary Information; the white dwarf data (Sample Two) are provided in Supplementary Tables 1–3, while data for Sample One can be found in ref. 26. Source data are provided with this paper.

Code availability

The code used to create Figs. 1–4 and the collisional evolution code is available at https://github.com/abonsor/collcascade and models for Fig. 2 are available at https://github.com/timlichtenberg/2stage_scripts_data.

References

  1. Scherstén, A., Elliott, T., Hawkesworth, C., Russell, S. & Masarik, J. Hf–W evidence for rapid differentiation of iron meteorite parent bodies. Earth Planet. Sci. Lett. 241, 530–542 (2006).

    Article  ADS  Google Scholar 

  2. Kruijer, T. S. et al. Protracted core formation and rapid accretion of protoplanets. Science 344, 1150–1154 (2014).

    Article  ADS  Google Scholar 

  3. Kleine, T. et al. The non-carbonaceous-carbonaceous meteorite dichotomy. Space Sci. Rev. 216, 55 (2020).

    Article  ADS  Google Scholar 

  4. Fedele, D., van den Ancker, M. E., Henning, T., Jayawardhana, R. & Oliveira, J. M. Timescale of mass accretion in pre-main-sequence stars. Astron. Astrophys. 510, A72 (2010).

    Article  Google Scholar 

  5. Najita, J. R. & Kenyon, S. J. The mass budget of planet-forming discs: isolating the epoch of planetesimal formation. Mon. Not. R. Astron. Soc. 445, 3315–3329 (2014).

    Article  ADS  Google Scholar 

  6. Tychoniec, Ł. et al. Dust masses of young disks: constraining the initial solid reservoir for planet formation. Astron. Astrophys. 640, A19 (2020).

    Article  Google Scholar 

  7. Sheehan, P. D. & Eisner, J. A. Multiple gaps in the disk of the class I protostar GY 91. Astrophys. J. 857, 18 (2018).

    Article  ADS  Google Scholar 

  8. Segura-Cox, D. M. et al. Four annular structures in a protostellar disk less than 500,000 years old. Nature 586, 228–231 (2020).

    Article  ADS  Google Scholar 

  9. Stammler, S. M. et al. The DSHARP rings: evidence of ongoing planetesimal formation? Astrophys. J. Lett. 884, L5 (2019).

    Article  ADS  Google Scholar 

  10. Carrera, D., Simon, J. B., Li, R., Kretke, K. A. & Klahr, H. Protoplanetary disk rings as sites for planetesimal formation. Astron. J. 161, 96 (2021).

    Article  ADS  Google Scholar 

  11. Flock, M. et al. Gaps, rings, and non-axisymmetric structures in protoplanetary disks. From simulations to ALMA observations. Astron. Astrophys. 574, A68 (2015).

    Article  Google Scholar 

  12. Zhang, K., Blake, G. A. & Bergin, E. A. Evidence of fast pebble growth near condensation fronts in the HL Tau protoplanetary disk. Astrophys. J. Lett. 806, L7 (2015).

    Article  ADS  Google Scholar 

  13. van der Marel, N. & Mulders, G. D. A stellar mass dependence of structured disks: a possible link with exoplanet demographics. Astron. J. 162, 28 (2021).

    Article  ADS  Google Scholar 

  14. Mulders, G. D., Pascucci, I., Ciesla, F. J. & Fernandes, R. B. The mass budgets and spatial scales of exoplanet systems and protoplanetary disks. Astrophys. J. 920, 66 (2021).

    Article  ADS  Google Scholar 

  15. Jura, M. & Young, E. D. Extrasolar cosmochemistry. Annu. Rev. Earth. Planet. Sci. 42, 45–67 (2014).

    Article  ADS  Google Scholar 

  16. Farihi, J. Circumstellar debris and pollution at white dwarf stars. N. Astron. Rev. 71, 9–34 (2016).

    Article  ADS  Google Scholar 

  17. Fontaine, G. & Michaud, G. Diffusion time scales in white dwarfs. Astrophys. J. 231, 826–840 (1979).

    Article  ADS  Google Scholar 

  18. Koester, D. Accretion and diffusion in white dwarfs. New diffusion timescales and applications to GD 362 and G 29-38. Astron. Astrophys. 498, 517–525 (2009).

    Article  ADS  Google Scholar 

  19. Zuckerman, B., Melis, C., Klein, B., Koester, D. & Jura, M. Ancient planetary systems are orbiting a large fraction of white dwarf stars. Astrophys. J. 722, 725–736 (2010).

    Article  ADS  Google Scholar 

  20. Koester, D., Gänsicke, B. T. & Farihi, J. The frequency of planetary debris around young white dwarfs. Astron. Astrophys. 566, A34 (2014).

    Article  ADS  Google Scholar 

  21. Melis, C. et al. Accretion of a terrestrial-like minor planet by a white dwarf. Astrophys. J. 732, 90 (2011).

    Article  ADS  Google Scholar 

  22. Gänsicke, B. T. et al. The chemical diversity of exo-terrestrial planetary debris around white dwarfs. Mon. Not. R. Astron. Soc. 424, 333–347 (2012).

    Article  ADS  Google Scholar 

  23. Wilson, D. J. et al. The composition of a disrupted extrasolar planetesimal at SDSS J0845+2257 (Ton 345). Mon. Not. R. Astron. Soc. 451, 3237–3248 (2015).

    Article  ADS  Google Scholar 

  24. Buchan, A. M. et al. Planets or asteroids? A geochemical method to constrain the masses of white dwarf pollutants. Mon. Not. R. Astron. Soc. 510, 3512–3530 (2022).

    Article  ADS  Google Scholar 

  25. Harrison, J. H. D., Bonsor, A. & Madhusudhan, N. Polluted white dwarfs: constraints on the origin and geology of exoplanetary material. Mon. Not. R. Astron. Soc. 479, 3814–3841 (2018).

    Article  ADS  Google Scholar 

  26. Harrison, J. H. D. et al. Bayesian constraints on the origin and geology of exoplanetary material using a population of externally polluted white dwarfs. Mon. Not. R. Astron. Soc. 504, 2853–2867 (2021).

    Article  ADS  Google Scholar 

  27. Krot, A. N., Amelin, Y., Cassen, P. & Meibom, A. Young chondrules in CB chondrites from a giant impact in the early Solar System. Nature 436, 989–992 (2005).

    Article  ADS  Google Scholar 

  28. Jura, M., Xu, S. & Young, E. D. 26Al in the early Solar System: not so unusual after all. Astrophys. J. Lett. 775, L41 (2013).

    Article  ADS  Google Scholar 

  29. Wasserburg, G. J., Lee, T. & Papanastassiou, D. A. correlated O And Mg isotopic anomalies in Allende inclusions: II. Magnesium. Geophys. Res. Lett. 4, 299–302 (1977).

    Article  ADS  Google Scholar 

  30. Tang, H. & Dauphas, N. Abundance, distribution, and origin of 60Fe in the solar protoplanetary disk. Earth Planet. Sci. Lett. 359, 248–263 (2012).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  32. Gounelle, M. The abundance of 26Al-rich planetary systems in the galaxy. Astron. Astrophys. 582, A26 (2015).

    Article  ADS  Google Scholar 

  33. Young, E. D. Inheritance of solar short- and long-lived radionuclides from molecular clouds and the unexceptional nature of the solar system. Earth Planet. Sci. Lett. 392, 16–27 (2014).

    Article  ADS  Google Scholar 

  34. Lichtenberg, T., Parker, R. J. & Meyer, M. R. Isotopic enrichment of forming planetary systems from supernova pollution. Mon. Not. R. Astron. Soc. 462, 3979–3992 (2016).

    Article  ADS  Google Scholar 

  35. Kuffmeier, M., Frostholm Mogensen, T., Haugbølle, T., Bizzarro, M. & Nordlund, Å. Tracking the distribution of 26Al and 60Fe during the early phases of star and disk evolution. Astrophys. J. 826, 22 (2016).

  36. Côté, B. et al. Galactic chemical evolution of radioactive isotopes. Astrophys. J. 878, 156 (2019).

    Article  ADS  Google Scholar 

  37. Fatuzzo, M. & Adams, F. C. Theoretical distributions of short-lived radionuclides for star formation in molecular clouds. Astrophys. J. 925, 56 (2022).

    Article  ADS  Google Scholar 

  38. Forbes, J. C., Alves, J. & Lin, D. N. C. A Solar System formation analogue in the Ophiuchus star-forming complex. Nat. Astron. 5, 1009–1016 (2021).

    Article  ADS  Google Scholar 

  39. Reiter, M. Observational constraints on the likelihood of 26Al in planet-forming environments. Astron. Astrophys. 644, L1 (2020).

    Article  ADS  Google Scholar 

  40. Lichtenberg, T., Dra̧żkowska, J., Schönbächler, M., Golabek, G. J. & Hands, T. O. Bifurcation of planetary building blocks during Solar System formation. Science 371, 365–370 (2021).

    Article  ADS  Google Scholar 

  41. Hughes, A. M., Duchêne, G. & Matthews, B. C. Debris disks: structure, composition, and variability. Annu. Rev. Astron. Astrophys. 56, 541–591 (2018).

    Article  ADS  Google Scholar 

  42. Marcus, R. A., Sasselov, D., Hernquist, L. & Stewart, S. T. Minimum radii of super-earths: constraints from giant impacts. Astrophys. J. Lett. 712, L73–L76 (2010).

    Article  ADS  Google Scholar 

  43. Carter, P. J., Leinhardt, Z. M., Elliott, T., Walter, M. J. & Stewart, S. T. Compositional evolution during rocky protoplanet accretion. Astrophys. J. 813, 72 (2015).

    Article  ADS  Google Scholar 

  44. Debes, J. H. & Sigurdsson, S. Are there unstable planetary systems around white dwarfs? Astrophys. J. 572, 556–565 (2002).

    Article  ADS  Google Scholar 

  45. Elkins-Tanton, L. T., Weiss, B. P. & Zuber, M. T. Chondrites as samples of differentiated planetesimals. Earth Planet. Sci. Lett. 305, 1–10 (2011).

    Article  ADS  Google Scholar 

  46. Payne, M. J., Veras, D., Holman, M. J. & Gänsicke, B. T. Liberating exomoons in white dwarf planetary systems. Mon. Not. R. Astron. Soc. 457, 217–231 (2016).

    Article  ADS  Google Scholar 

  47. Veras, D., Mustill, A. J., Bonsor, A. & Wyatt, M. C. Simulations of two-planet systems through all phases of stellar evolution: implications for the instability boundary and white dwarf pollution. Mon. Not. R. Astron. Soc. 431, 1686–1708 (2013).

    Article  ADS  Google Scholar 

  48. Veras, D. Post-main-sequence planetary system evolution. R. Soc. Open Sci. 3, 150571 (2016).

    Article  ADS  Google Scholar 

  49. Farihi, J. et al. Scars of intense accretion episodes at metal-rich white dwarfs. Mon. Not. R. Astron. Soc. 424, 464–471 (2012).

    Article  ADS  Google Scholar 

  50. Krivov, A. V. & Wyatt, M. C. Solution to the debris disc mass problem: planetesimals are born small? Mon. Not. R. Astron. Soc. 500, 718–735 (2021).

    Article  ADS  Google Scholar 

  51. Wyatt, M. C. Evolution of debris disks. Annu. Rev. Astron. Astrophys. 46, 339–383 (2008).

    Article  ADS  Google Scholar 

  52. Wyatt, M. C. et al. Steady state evolution of debris disks around a stars. Astrophys. J. 663, 365–382 (2007).

    Article  ADS  Google Scholar 

  53. Lichtenberg, T. & Krijt, S. System-level fractionation of carbon from disk and planetesimal processing. Astrophys. J. Lett. 913, L20 (2021).

    Article  ADS  Google Scholar 

  54. Wordsworth, R. & Kreidberg, L. Atmospheres of rocky exoplanets. Preprint at https://arxiv.org/abs/2112.04663 (2021).

  55. Dra̧żkowska, J., Stammler, S. M. & Birnstiel, T. How dust fragmentation may be beneficial to planetary growth by pebble accretion. Astron. Astrophys. 647, A15 (2021).

    Article  ADS  Google Scholar 

  56. Brewer, J. M., Fischer, D. A., Valenti, J. A. & Piskunov, N. Spectral properties of cool stars: extended abundance analysis of 1,617 planet-search stars. Astrophys. J. Suppl. Ser. 225, 32 (2016).

    Article  ADS  Google Scholar 

  57. Fischer, R. A. et al. High pressure metal-silicate partitioning of Ni, Co, V, Cr, Si, and O. Geochim. Cosmochim. Acta 167, 177–194 (2015).

    Article  ADS  Google Scholar 

  58. Corgne, A. & Wood, B. J. Element partitioning during core formation. Geochim. Cosmochim. Acta 72(Suppl), A178 (2008).

    Google Scholar 

  59. Wade, J. & Wood, B. J. Core formation and the oxidation state of the Earth. Earth Planet. Sci. Lett. 236, 78–95 (2005).

    Article  ADS  Google Scholar 

  60. Wood, B. J., Wade, J. & Kilburn, M. R. Core formation and the oxidation state of the Earth: additional constraints from Nb, V and Cr partitioning. Geochim. Cosmochim. Acta 72, 1415–1426 (2008).

    Article  ADS  Google Scholar 

  61. Cottrell, E., Walter, M. J. & Walker, D. Metal-silicate partitioning of tungsten at high pressure and temperature: Implications for equilibrium core formation in Earth. Earth Planet. Sci. Lett. 281, 275–287 (2009).

    Article  ADS  Google Scholar 

  62. Siebert, J., Badro, J., Antonangeli, D. & Ryerson, F. J. Metal-silicate partitioning of Ni and Co in a deep magma ocean. Earth Planet. Sci. Lett. 321, 189–197 (2012).

    Article  ADS  Google Scholar 

  63. Hollands, M. A., Koester, D., Alekseev, V., Herbert, E. L. & Gänsicke, B. T. Cool DZ white dwarfs - I. Identification and spectral analysis. Mon. Not. R. Astron. Soc. 467, 4970–5000 (2017).

    ADS  Google Scholar 

  64. Hollands, M. A., Gänsicke, B. T. & Koester, D. Cool DZ white dwarfs II:compositions and evolution of old remnant planetary systems. Mon. Not. R. Astron. Soc. 477, 93 (2018).

    Article  ADS  Google Scholar 

  65. Blouin, S. Magnesium abundances in cool metal-polluted white dwarfs. Mon. Not. R. Astron. Soc. 496, 1881–1890 (2020).

    Article  ADS  Google Scholar 

  66. Bonsor, A. et al. Are exoplanetesimals differentiated? Mon. Not. R. Astron. Soc. 492, 2683–2697 (2020).

    Article  ADS  Google Scholar 

  67. Hollands, M. A., Tremblay, P.-E., Gänsicke, B. T., Koester, D. & Gentile-Fusillo, N. P. Alkali metals in white dwarf atmospheres as tracers of ancient planetary crusts. Nat. Astron. 5, 451–459 (2021).

    Article  ADS  Google Scholar 

  68. Zuckerman, B. et al. An aluminum/calcium-rich, iron-poor, white dwarf star: evidence for an extrasolar planetary lithosphere? Astrophys. J. 739, 101 (2011).

    Article  ADS  Google Scholar 

  69. Sellke, T., Bayarri, M. J. & Berger, J. O. Calibration of rho values for testing precise null hypotheses. Am. Stat. 55, 62–71 (2001).

    Article  MATH  Google Scholar 

  70. Xu, S. et al. Compositions of planetary debris around dusty white dwarfs. Astron. J. 158, 242 (2019).

    Article  ADS  Google Scholar 

  71. Wyatt, M. C., Clarke, C. J. & Booth, M. Debris disk size distributions: steady state collisional evolution with Poynting-Robertson drag and other loss processes. Celest. Mech. Dynam. Astron. 111, 1–28 (2011).

    Article  ADS  MATH  Google Scholar 

  72. Dohnanyi, J. S. Collisional model of asteroids and their debris. J. Geophys. Res. 74, 2531–+ (1969).

    Article  ADS  Google Scholar 

  73. Benz, W. & Asphaug, E. Catastrophic disruptions revisited. Icarus 142, 5–20 (1999).

    Article  ADS  Google Scholar 

  74. Durda, D. D., Greenberg, R. & Jedicke, R. Collisional models and scaling laws: a new interpretation of the shape of the main-belt asteroid size distribution. Icarus 135, 431–440 (1998).

    Article  ADS  Google Scholar 

  75. Löhne, T., Krivov, A. V. & Rodmann, J. Long-term collisional evolution of debris disks. Astrophys. J. 673, 1123–1137 (2008).

    Article  ADS  Google Scholar 

  76. Wyatt, M. C. et al. Transience of hot dust around Sun-like stars. Astrophys. J. 658, 569–583 (2007).

    Article  ADS  Google Scholar 

  77. Bonsor, A. & Wyatt, M. Post-main-sequence evolution of a star debris discs. Mon. Not. R. Astron. Soc. 409, 1631–1646 (2010).

    Article  ADS  Google Scholar 

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Acknowledgements

A.B. acknowledges support from a Royal Society Dorothy Hodgkin Research Fellowship (grant number DH150130) and a Royal Society University Research Fellowship (grant number URF\R1\211421). T.L. was supported by a grant from the Simons Foundation (SCOL award number 611576). J.D. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement number 714769. A.M.B. acknowledges support from a Royal Society funded PhD studentship (grant number RGFEA180174). We acknowledge fruitful discussions with M. Brouwers, L. Rogers, E. Lynch, A. Curry, T. Birnstiel, M. Wyatt and R. J. Parker.

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Author notes

  1. These authors contributed equally: Tim Lichtenberg, Joanna Dra̧żkowska, Andrew M. Buchan.

Authors and Affiliations

  1. Institute of Astronomy, University of Cambridge, Cambridge, UK

    Amy Bonsor & Andrew M. Buchan

  2. Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, UK

    Tim Lichtenberg

  3. Kapteyn Astronomical Institute, University of Groningen, Groningen, the Netherlands

    Tim Lichtenberg

  4. University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität München, Munich, Germany

    Joanna Dra̧żkowska

  5. Max Planck Institute for Solar System Research, Göttingen, Germany

    Joanna Dra̧żkowska

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Contributions

The idea for the study came from discussions between A.B., J.D. and T.L. The analysis of the white dwarf data was performed by A.M.B. and T.L. supplied the thermal evolution models used for Fig. 2. All authors contributed to writing the manuscript.

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Correspondence to Amy Bonsor.

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Bonsor, A., Lichtenberg, T., Dra̧żkowska, J. et al. Rapid formation of exoplanetesimals revealed by white dwarfs. Nat Astron 7, 39–48 (2023). https://doi.org/10.1038/s41550-022-01815-8

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