Abstract
We investigate the role of mass infall in the formation and evolution of
protostars. To avoid ad hoc initial and boundary conditions, we
consider the infall resulting self-consistently from modeling the
formation of stellar clusters in turbulent molecular clouds. We show
that infall rates in turbulent clouds are comparable to accretion rates
inferred from protostellar luminosities or measured in pre-main-sequence
stars. They should not be neglected in modeling the luminosity of
protostars and the evolution of disks, even after the embedded
protostellar phase. We find large variations of infall rates from
protostar to protostar, and large fluctuations during the evolution of
individual protostars. In most cases, the infall rate is initially of
order 10–5 M ☉ yr–1, and may
either decay rapidly in the formation of low-mass stars, or remain
relatively large when more massive stars are formed. The simulation
reproduces well the observed characteristic values and scatter of
protostellar luminosities and matches the observed protostellar
luminosity function. The luminosity problem is therefore solved once
realistic protostellar infall histories are accounted for, with no need
for extreme accretion episodes. These results are based on a simulation
of randomly driven magnetohydrodynamic turbulence on a scale of 4 pc,
including self-gravity, adaptive-mesh refinement to a resolution of 50
AU, and accreting sink particles. The simulation yields a low star
formation rate, consistent with the observations, and a mass
distribution of sink particles consistent with the observed stellar
initial mass function during the whole duration of the simulation,
forming nearly 1300 sink particles over 3.2 Myr.
| Original language | English |
|---|---|
| Article number | 32 |
| Journal | The Astrophysical Journal |
| Volume | 797 |
| Issue number | 1 |
| Number of pages | 20 |
| ISSN | 0004-637X |
| DOIs | |
| Publication status | Published - 10 Dec 2014 |