Disc fragmentation rarely forms planetary-mass objects

Ken Rice, Eric Lopez, Duncan Forgan, Beth Biller

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


It is now reasonably clear that disc fragmentation can only operate in the outer parts of protostellar discs (r > 50 au). It is also expected that any object that forms via disc fragmentation will have an initial mass greater than that of Jupiter. However, whether or not such a process actually operates, or can play a significant role in the formation of planetary-mass objects, is still unclear. We do have a few examples of directly imaged objects that may have formed in this way, but we have yet to constrain how often disc fragmentation may actually form such objects. What we want to consider here is whether or not we can constrain the likely population of planetary-mass objects formed via disc fragmentation by considering how a population of objects at large radii (a > 50) au - if they do exist - would evolve under perturbations from more distant stellar companions. We find that there is a specific region of parameter space to which such objects would bes cattered and show that the known exoplanets in that region have properties more consistent with that of the bulk exoplanet population, than with having been formed via disc fragmentation at large radii. Along with the scarcity of directly imaged objects at large radii, our results provide a similar, but independent, constraint on the frequency of objects formed via disc fragmentation.
Original languageEnglish
Pages (from-to)1940-1947
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date9 Oct 2015
Publication statusPublished - 1 Dec 2015


  • Planets and satellites: formation
  • Planets and satellites: general
  • Brown dwarfs
  • Stars: formation


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