The importance of episodic accretion for low-mass star formation

TL;DR

This paper introduces a new simulation method that models episodic accretion in star formation, showing how bursts of luminosity influence disc stability and the formation of low-mass stars and objects.

Contribution

It presents a novel approach to include episodic accretion effects in star formation simulations, highlighting its role in low-mass star and brown dwarf formation.

Findings

Episodic accretion causes short, intense luminosity bursts.

Luminosity lulls allow disc cooling and fragmentation.

Episodic accretion impacts the low-mass stellar initial mass function.

Abstract

A star acquires much of its mass by accreting material from a disc. Accretion is probably not continuous but episodic. We have developed a method to include the effects of episodic accretion in simulations of star formation. Episodic accretion results in bursts of radiative feedback, during which a protostar is very luminous, and its surrounding disc is heated and stabilised. These bursts typically last only a few hundred years. In contrast, the lulls between bursts may last a few thousand years; during these lulls the luminosity of the protostar is very low, and its disc cools and fragments. Thus, episodic accretion enables the formation of low-mass stars, brown dwarfs and planetary-mass objects by disc fragmentation. If episodic accretion is a common phenomenon among young protostars, then the frequency and duration of accretion bursts may be critical in determining the low-mass end of the stellar initial mass function.