Collisions of free-floating planets with evolved stars in globular clusters

Noam Soker*, Saul Rappaport, John Fregeau

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We estimate the rate of collisions between stars and free-floating planets (FFPs) in globular clusters, in particular, the collision of FFPs with red giant branch (RGB) stars. Recent dynamical simulations imply that the density of such objects could exceed ∼106 pc -3 near the cores of rich globular clusters. We show that in these clusters ∼5%-10% of all RGB stars near the core would suffer a collision with an FFP and that such a collision can spin up the RGB star's envelope by an order of magnitude. In turn, the higher rotation rates may lead to enhanced mass-loss rates on the RGB, which could result in bluer horizontal branch (HB) stars. Hence, it is plausible that the presence of a large population of FFPs in a globular cluster can influence the distribution of stars on the HB of that cluster to a detectable degree.

Original languageEnglish
Pages (from-to)L87-L90
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - 10 Dec 2001
Externally publishedYes


  • Globular clusters: General
  • Planetary systems
  • Stars: General
  • Stars: Horizontal-branch
  • Stars: Mass loss
  • Stars: Rotation

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