  The standard picture of accretion is a steady flow of matter from the disc
onto the young star - a concept which assumes the star-disc system to be
completely isolated. However, in a dense cluster environment star-disc systems
do interact gravitationally. The aim here is to estimate the encounter-induced
accretion rate in an ONC-like environment. Combining simulations of the cluster
dynamics with simulations of the effect of encounters on star-disc systems we
determine the likelihood and degree of encounter-triggered accretion processes.
We show that accretion bursts triggered by encounters of star-disc systems are
common in young dense clusters like the ONC leading in the outburst phase to
typical accretion rates of 10^(-7)-10^(-4) M(sun)/yr. Up to a third of stars
presently in the Trapezium region accreted at least 1% of their disc mass via
this mechanism in the last 1Myr. Accretion of over 6-7% of the disc material
can occur in a single encounter. Despite losing their discs quickly, the total
percentage of disc matter accreted per star is largest for the massive stars.
Supplementing the steady accretion flow there exist episodic periods of high
accretion in dense cluster environments. Due to their high accretion rate these
processes should be observable even now in some of the low-mass stars in the
ONC.
