The birth and early evolution of a low mass protostar

Abstract

Understanding the collapse of dense molecular cloud cores to stellar densities and the subsequent evolution of the protostar is of importance to model the feedback effects such an object has on its surrounding environment, as well as describing the conditions with which it enters the stellar evolutionary track. This process is fundamentally multi-scale and necessitates the use of robust numerical simulations. We aim to model the birth and early evolution of a low-mass protostar. We also seek to describe the interior structure of the protostar and the radiative behavior of its accretion shock front. We carry out a high resolution numerical simulation of the collapse of a gravitationally unstable $1$ ${\mathrm{M}}_{\odot }$ dense molecular cloud core to stellar densities using three-dimensional radiation hydrodynamics under the gray flux-limited diffusion approximation. We follow the initial isothermal phase, the first adiabatic contraction, the second gravitational collapse triggered by the dissociation of ${\mathrm{H}}_2$ molecules, and $\approx 247$ days of the subsequent main accretion phase. We find that the sub-critical radiative behavior of the protostar's shock front causes it to swell as it accretes matter. We also find that the protostar is turbulent from the moment of its inception despite its radiative stability. This turbulence causes significant entropy mixing inside the protostar, which regulates the swelling. Furthermore, we find that the protostar is not fully ionized at birth, but the relative amount of ionized material within it increases as it accretes matter from its surroundings. Finally, we report in the appendix the results of the first 3D calculations involving a frequency-dependent treatment of radiative transfer, which has not produced any major differences with its gray counterpart.

Accepted for publication in A&A, 23 pages, 27 figures

References in corpus (17)

• Theory of Star Formation
• Instability of a stalled accretion shock: evidence for the advective-acoustic cycle
• Variable protostellar accretion with episodic bursts
• Magnetic Fields and Rotations of Protostars
• The dynamics and outcome of star formation with jets, radiation, winds, and supernovae in concert
• Towards a more realistic sink particle algorithm for the RAMSES code
• Effects of Ohmic and ambipolar diffusion on the formation and evolution of the first cores, protostars and circumstellar discs
• Second Core Formation and High Speed Jets: Resistive MHD Nested Grid Simulations
• Grand Design Spiral Arms in A Young Forming Circumstellar Disk
• Exposed Long-lifetime First-core: A New Model of First Cores Based on Radiation Hydrodynamics
• Protoplanetary disk birth in massive star forming clumps: the essential role of the magnetic field
• First Magnetic Field Detection on a Class I Protostar
• Non-ideal magnetohydrodynamics vs turbulence I: Which is the dominant process in protostellar disc formation?
• Multigroup radiation hydrodynamics with flux-limited diffusion and adaptive mesh refinement
• Birth of convective low-mass to high-mass second Larson cores
• Non-ideal magnetohydrodynamics vs turbulence II: Which is the dominant process in stellar core formation?
• On the origin of magnetic fields in stars II: The effect of numerical resolution

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