Edinburgh Research Explorer

Substellar companions and isolated planetary-mass objects from protostellar disc fragmentation

Research output: Contribution to journalArticle

  • W. K. M. Rice
  • P. J. Armitage
  • I. A. Bonnell
  • M. R. Bate
  • S. V. Jeffers
  • S. G. Vine

Related Edinburgh Organisations

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Publication statusPublished - 1 Dec 2003


Self-gravitating protostellar discs are unstable to fragmentation if the gas can cool on a time-scale that is short compared with the orbital period. We use a combination of hydrodynamic simulations and N-body orbit integrations to study the long-term evolution of a fragmenting disc with an initial mass ratio to the star of Mdisc/M*= 0.1. For a disc that is initially unstable across a range of radii, a combination of collapse and subsequent accretion yields substellar objects with a spectrum of masses extending (for a Solar-mass star) up to ~0.01 Msolar. Subsequent gravitational evolution ejects most of the lower mass objects within a few million years, leaving a small number of very massive planets or brown dwarfs in eccentric orbits at moderately small radii. Based on these results, systems such as HD 168443 - in which the companions are close to or beyond the deuterium burning limit - appear to be the best candidates to have formed via gravitational instability. If massive substellar companions originate from disc fragmentation, while lower-mass planetary companions originate from core accretion, the metallicity distribution of stars which host massive substellar companions at radii of ~1 au should differ from that of stars with lower mass planetary companions.

    Research areas

  • accretion, accretion discs, planets and satellites: formation, stars: low-mass, brown dwarfs, planetary systems: protoplanetary discs, stars: pre-main sequence

ID: 19683776