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Anders Johansen. Profile picture.

Anders Johansen

Professor

Anders Johansen. Profile picture.

Debris disc constraints on planetesimal formation

Author

  • Alexander V. Krivov
  • Aljoscha Ide
  • Torsten Löhne
  • Anders Johansen
  • Jürgen Blum

Summary, in English

Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical 'slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentrationmodels - provided the objects are loosely bound 'pebble piles' as thesemodels also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a 'disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ~1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.

Department/s

  • Lund Observatory

Publishing year

2018

Language

English

Pages

2564-2575

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

474

Issue

2

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Circumstellar matter
  • Comets: general
  • Infrared: planetary systems
  • Planets and satellites: formation
  • Protoplanetary discs

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711