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Anders Johansen. Profile picture.

Anders Johansen

Professor

Anders Johansen. Profile picture.

The Formation of Giant Planets

Author

  • Michiel Lambrechts

Summary, in English

Giant planets form embedded in a protoplanetary disc around a young star. Close to the midplane a large fraction of the available mass in solids is found in particles of cm to dm in size, which drift towards the star due to friction with the surrounding gas.

In paper I, II, III we describe a novel theory that explains how embryos, planetesimals larger than ~1000 km, grow efficiently by sweeping up the surrounding pebbles. The accretion radius of the embryo is large because gas drag aids the settling of passing pebbles to the core. In this way, the formation of large cores of 10 Earth masses is possible even in wide orbits (beyond the current Jupiter orbit), which previously could not be achieved when only considering the accretion of building blocks with sizes larger than km in size. Such high core masses are necessary for the attraction of massive gaseous envelopes, like the ones around the giant planets Jupiter and Saturn.



The above model relies on large planetesimal seeds to form and particles to settle to the midplane.

In paper IV, we study the previously unexplored sedimentation of particles in fluids with high dust-to-gas ratio and detect spontaneous clumping which could aid the sedimentation and formation of a midplane of pebbles in the outer disc.

Department/s

  • Lund Observatory - Undergoing reorganization

Publishing year

2015

Language

English

Document type

Dissertation

Publisher

Department of Astronomy and Theoretical Physics, Lund University

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Planet formation
  • Solar System
  • Exoplanets
  • Giant planets
  • Hydrodynamics

Status

Published

Supervisor

  • Anders Johansen

ISBN/ISSN/Other

  • ISBN: 978-91-7623-269-9

Defence date

9 March 2015

Defence time

09:00

Defence place

Lundmarksalen (Department of Astronomy and Theoretical Physics)

Opponent

  • Roman Rafikov (Dr.)