Competitive accretion in embedded stellar clusters

Abstract

We investigate the physics of gas accretion in young stellar clusters.\nAccretion in clusters is a dynamic phenomenon as both the stars and the gas\nrespond to the same gravitational potential. Accretion rates are highly\nnon-uniform with stars nearer the centre of the cluster, where gas densities\nare higher, accreting more than others. This competitive accretion naturally\nresults in both initial mass segregation and a spectrum of stellar masses.\nAccretion in gas-dominated clusters is well modelled using a tidal-lobe radius\ninstead of the commonly used Bondi-Hoyle accretion radius. This works as both\nthe stellar and gas velocities are under the influence of the same\ngravitational potential and are thus comparable. The low relative velocity that\nresults means that the tidal radius is smaller than the Bondi-Hoyle radius in\nthese systems. In contrast, when the stars dominate the potential and are\nvirialised, the Bondi-Hoyle radius is smaller than the tidal radius and thus\nBondi-Hoyle accretion is a better fit to the accretion rates.\n

Keywords

Affiliated Institutions

• Institute of Astronomy RU
• University of St Andrews GB

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