On the rise times in FU Orionis events

Abstract

ABSTRACT We examine whether stellar flyby simulations can initiate FU Orionis outbursts using 3D hydrodynamics simulations coupled to live Monte Carlo radiative transfer. We find that a flyby where the secondary penetrates the circumprimary disc triggers a 1–2 yr rise in the mass accretion rate to 10−4 M⊙ yr−1 that remains high (≳10−5 M⊙ yr−1) for more than a hundred years, similar to the outburst observed in FU Ori. Importantly, we find that the less massive star becomes the dominant accretor, as observed.