The Effects of Radiative Transfer on Low-Mass Star Formation

TL;DR

This study uses advanced simulations to show that radiative feedback from forming stars significantly influences star formation processes, reducing star numbers, affecting accretion, and preventing disk fragmentation, thus altering the initial mass function.

Contribution

It provides the first detailed three-dimensional radiation hydrodynamics simulation demonstrating the profound impact of protostellar radiation on low-mass star formation.

Findings

Radiative feedback reduces the number of stars formed.

Protostellar radiation dominates energy output in steady state.

Heating suppresses disk fragmentation, affecting low-mass companion formation.

Abstract

Forming stars emit a substantial amount of radiation into their natal environment. We use ORION, an adaptive mesh refinement (AMR) three-dimensional gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent molecular cloud. We compare the distribution of stellar masses, accretion rates, and temperatures in the cases with and without radiative transfer, and we demonstrate that radiative feedback has a profound effect on accretion, multiplicity, and mass by reducing the number of stars formed and the total rate at which gas turns into stars. We also show, that once star formation reaches a steady state, protostellar radiation is by far the dominant source of energy in the simulation, exceeding viscous dissipation and compressional heating by at least an order of magnitude. Calculations that omit radiative feedback from protstars significantly underestimate the gas temperature and the strength of this effect. Although heating from protostars is mainly confined to the protostellar cores, we find that it is sufficient to suppress disk fragmentation that would otherwise result in very low-mass companions or brown dwarfs. We demonstrate that the mean protostellar accretion rate increases with the final stellar mass so that the star formation time is only a weak function of mass.