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Two families of exocomets in the β Pictoris system

Nature volume 514, pages 462464 (23 October 2014) | Download Citation

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Abstract

The young planetary system surrounding the star β Pictoris harbours active minor bodies1,2,3,4,5,6. These asteroids and comets produce a large amount of dust and gas through collisions and evaporation, as happened early in the history of our Solar System7. Spectroscopic observations of β Pictoris reveal a high rate of transits of small evaporating bodies8,9,10,11, that is, exocomets. Here we report an analysis of more than 1,000 archival spectra gathered between 2003 and 2011, which provides a sample of about 6,000 variable absorption signatures arising from exocomets transiting the disk of the parent star. Statistical analysis of the observed properties of these exocomets allows us to identify two populations with different physical properties. One family consists of exocomets producing shallow absorption lines, which can be attributed to old exhausted (that is, strongly depleted in volatiles) comets trapped in a mean motion resonance with a massive planet. Another family consists of exocomets producing deep absorption lines, which may be related to the recent fragmentation of one or a few parent bodies. Our results show that the evaporating bodies observed for decades in the β Pictoris system are analogous to the comets in our own Solar System.

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Acknowledgements

This work was based on observations made with ESO telescopes at the La Silla Observatory and data obtained from the ESO Science Archive Facility. This work has been supported by an award from the Fondation Simone et Cino Del Duca. We also acknowledge support from the French Agence Nationale de la Recherche (ANR), under programmes ANR-12-BS05-0012 Exo-Atmos and ANR-2010 BLAN-0505-01 (EXOZODI). We thank P. A. Wilson for his comments on the manuscript.

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Affiliations

  1. Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 7095, Institut d’Astrophysique de Paris, 98 bis boulevard Arago, F-75014 Paris, France

    • F. Kiefer
    • , A. Lecavelier des Etangs
    • , A. Vidal-Madjar
    • , G. Hébrard
    •  & R. Ferlet
  2. Université Pierre et Marie Curie, UMR 7095, Institut d’Astrophysique de Paris, 98 bis boulevard Arago, F-75014 Paris, France

    • F. Kiefer
    • , A. Lecavelier des Etangs
    • , A. Vidal-Madjar
    • , G. Hébrard
    •  & R. Ferlet
  3. School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel

    • F. Kiefer
  4. Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 Saint Martin d’Hères, France

    • J. Boissier
  5. Université Joseph Fourier-Grenoble 1/CNRS– Institut National des Sciences de l’Univers, Institut de Planétologie et d’Astrophysique de Grenoble, UMR 5274, 414 Rue de la Piscine, 38400 St-Martin d’Hères, France

    • H. Beust
    •  & A.-M. Lagrange

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Contributions

F.K. led the data analysis, with contributions from A.L.d.E., J.B., A.V.-M., R.F. and G.H.; F.K. and A.L.d.E. wrote the paper; H.B. computed mean-motion resonance curves and developed theoretical modelling; A.L.d.E., A.V.-M., A.-M.L. and H.B. contributed to the conception of the project. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to F. Kiefer or A. Lecavelier des Etangs.

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https://doi.org/10.1038/nature13849

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