Formation of low mass protostars and their circumstellar disks

Abstract

The birth process of circumstellar disks remains poorly constrained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often wrapped into a sub-grid model, play a crucial role in disk formation and evolution. This calls for a combined approach in which both the protostar and circumstellar disk are studied in concert. We aim to elucidate the small scale physics and constrain sub-grid parameters commonly chosen in the literature by resolving the star-disk interaction. We carry out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe the collapse of a turbulent dense molecular cloud core to stellar densities. We study the birth of the protostar, the circumstellar disk, and its early evolution (< 6 yr after protostellar formation). Following the second gravitational collapse, the nascent protostar quickly reaches breakup velocity and sheds its surface material, thus forming a hot ($\sim 10^3$ K), dense, and highly flared circumstellar disk. The protostar is embedded within the disk, such that material can flow without crossing any shock fronts. The circumstellar disk mass quickly exceeds that of the protostar, and its kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, and accretion onto the protostar mainly occurs through material that slides on the disk surface. The polar mass flux is negligible in comparison. The radiative behavior also displays a strong anisotropy, as the polar accretion shock is shown to be supercritical whereas its equatorial counterpart is subcritical. We also find a remarkable convergence of our results with respect to initial conditions. These results reveal the structure and kinematics in the smallest spatial scales relevant to protostellar and circumstellar disk evolution.

Accepted for publication in A&A, 17 pages, 15 figures

References in corpus (28)

• On the diversity and statistical properties of protostellar discs
• The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. A Statistical Characterization of Class 0 and I Protostellar Disks
• Circumventing the radiation pressure barrier in the formation of massive stars via disk accretion
• Radiation Magnetohydrodynamic Simulations of Protostellar Collapse: Non-Ideal Magnetohydrodynamic Effects and Early Formation of Circumstellar Disks
• 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
• The First Two Thousand Years of Star Formation
• Protostellar collapse simulations in spherical geometry with dust coagulation and fragmentation
• Protoplanetary disk birth in massive star forming clumps: the essential role of the magnetic field
• Collapse of turbulent massive cores with ambipolar diffusion and hybrid radiative transfer I. Accretion and multiplicity
• Formation and Early Evolution of Circumstellar Disks in Turbulent Molecular Cloud Cores
• Multigroup radiation hydrodynamics with flux-limited diffusion and adaptive mesh refinement
• The impact of non-ideal magnetohydrodynamic processes on discs, outflows, counter-rotation and magnetic walls during the early stages of star formation
• Birth of convective low-mass to high-mass second Larson cores
• Collapse of turbulent massive cores with ambipolar diffusion and hybrid radiative transfer II. Outflows
• Non-ideal magnetohydrodynamics vs turbulence II: Which is the dominant process in stellar core formation?
• Modeling disks and magnetic outflows around a forming massive star: I. Investigating the two layer-structure of the accretion disk
• The birth and early evolution of a low mass protostar
• Co-evolution of dust grains and protoplanetary disks
• A two-step gravitational cascade for the fragmentation of self-gravitating discs
• On the origin of magnetic fields in stars II: The effect of numerical resolution
• The role of magnetic fields in the formation of multiple massive stars
• The Near Stellar Environment of Class 0 Protostars: A First Look with Near-Infrared Spectroscopy
• Accuracy of ALMA estimates of young disk radii and masses. Predicted observations from numerical simulations
• Impact of turbulence intensity and fragmentation velocity on dust particle size evolution and non-ideal magnetohydrodynamics effects

Cited by in corpus (7)

• Formation and evolution of a protoplanetary disk: combining observations, simulations and cosmochemical constraints
• Birth of magnetized low-mass protostars and circumstellar disks
• The High-resolution Accretion Disks of Embedded protoStars (HADES) simulations. I. Impact of Protostellar Magnetic Fields on the Accretion Modes
• Turn up the light: Radiative efficiency of protostars at birth
• Non-equilibrium condensation of the first Solar System solids
• Numerical Insights into Disk Accretion, Eccentricity, and Kinematics in the Class 0 phase
• DAWN. I. Simulating the formation and early evolution of stellar clusters with Phantom N-Body