We investigate the physics of gas accretion in young stellar clusters.
Accretion in clusters is a dynamic phenomenon as both the stars and the gas
respond to the same gravitational potential. Accretion rates are highly
non-uniform with stars nearer the centre of the cluster, where gas densities
are higher, accreting more than others. This competitive accretion naturally
results in both initial mass segregation and a spectrum of stellar masses.
Accretion in gas-dominated clusters is well modelled using a tidal-lobe radius
instead of the commonly used Bondi-Hoyle accretion radius. This works as both
the stellar and gas velocities are under the influence of the same
gravitational potential and are thus comparable. The low relative velocity that
results means that the tidal radius is smaller than the Bondi-Hoyle radius in
these systems. In contrast, when the stars dominate the potential and are
virialised, the Bondi-Hoyle radius is smaller than the tidal radius and thus
Bondi-Hoyle accretion is a better fit to the accretion rates.Comment: 11 pages, 11 figures, MNRAS in pres
