Open AccessFree‐floating planets in stellar clusters?
Author(s) -
Smith Kester W.,
Bonnell Ian A.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04321.x
Subject(s) - physics , globular cluster , planet , astrophysics , cluster (spacecraft) , stars , eccentricity (behavior) , open cluster , planetary system , astronomy , population , star cluster , demography , sociology , computer science , political science , law , programming language
We have simulated encounters between planetary systems and single stars in various clustered environments. This allows us to estimate the fraction of systems liberated, the velocity distribution of the liberated planets, and the separation and eccentricity distributions of the surviving bound systems. Our results indicate that, for an initial distribution of orbits that is flat in log space and extends out to 50 au, 50 per cent of the available planets can be liberated in a globular cluster, 25 per cent in an open cluster, and less than 10 per cent in a young cluster. These fractions are reduced to 25, 12 and 2 per cent if the initial population extends only to 20 au. Furthermore, these free‐floating planets can be retained for longer than a crossing time only in a massive globular cluster. It is therefore difficult to see how planets, which by definition form in a disc around a young star, could be subsequently liberated to form a significant population of free‐floating substellar objects in a cluster.