Protostellar disc structure and dynamics during star formation from cloud-scale initial conditions

Abstract

The early evolution of protostellar, star-forming discs, including their density structure, turbulence, magnetic dynamics, and accretion variability, remains poorly understood. We present high-resolution magnetohydrodynamic simulations, using adaptive mesh refinement to capture detailed disc dynamics down to sub-AU scales. Starting from initial conditions derived from a molecular cloud simulation, we model the collapse of a dense core into a protostellar disc over 10,000 yr following sink particle (star) formation, achieving a maximum effective resolution of 0.63 AU. This simulation traces the evolution of the disc density, accretion rates, turbulence, and magnetic field structures. We find that the protostellar disc grows to a diameter of approximately 100 AU, with mass accretion occurring in episodic bursts influenced by the turbulence of the core from which the disc builds up. The disc is highly turbulent with a sonic Mach number of $\sim 2$. Episodic accretion events within the disc cause intermittent increases in mass and magnetic energy density, resulting in an equipartition of the thermal and magnetic pressure, i.e., leading to an Alfvén Mach number of $\sim 2$. Some regions above and below the disc mid-plane show sub-Alfvénic conditions with intermittent outflow activity. The disc density profiles steepen over time, following a power law consistent with observed young stellar discs and the minimum mass solar nebula. These results underscore the role of turbulence in early accretion variability and offer new insights into the physical and magnetic structure of young protostellar discs, especially with respect to their turbulent components.

19 pages, 18 figures, 3 tables. Submitted to MNRAS. See https://treyyang.com/projects/disc2024/ for animations prior to publication. Alfvén surface analysis added; velocity study corrected; references added

References in corpus (89)

• Theory of Star Formation
• Control of star formation by supersonic turbulence
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• Interstellar Turbulence I: Observations and Processes
• Modelling Accretion in Protobinary Systems
• Comparing the statistics of interstellar turbulence in simulations and observations: Solenoidal versus compressive turbulence forcing
• The Star Formation Rate of Turbulent Magnetized Clouds: Comparing Theory, Simulations, and Observations
• Protoplanetary Disk Structures in Ophiuchus
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• The Statistics of Supersonic Isothermal Turbulence
• Thermal and Fragmentation Properties of Star-forming Clouds in Low-metallicity Environments
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Turbulent molecular clouds
• On the diversity and statistical properties of protostellar discs
• The Effects of Radiative Transfer on Low-Mass Star Formation
• Simulating the formation of molecular clouds. I. Slow formation by gravitational collapse from static initial conditions
• A new Jeans resolution criterion for (M)HD simulations of self-gravitating gas: Application to magnetic field amplification by gravity-driven turbulence
• On the universality of supersonic turbulence
• The structure of protoplanetary discs around evolving young stars
• On the Diversity of the Taurus Transitional Disks: UX Tau A & Lk Ca 15
• Simulating the formation of molecular clouds. II. Rapid formation from turbulent initial conditions
• The Importance of Radiative Feedback for the Stellar Initial Mass Function
• Embedding Lagrangian Sink Particles in Eulerian Grids
• Inefficient star formation through turbulence, magnetic fields and feedback
• The impact of magnetic fields on single and binary star formation
• Filaments and ridges in Vela C revealed by Herschel: from low-mass to high-mass star-forming sites
• The spine of the swan: A Herschel study of the DR21 ridge and filaments in Cygnus X
• Characterising the Gravitational Instability in Cooling Accretion Discs
• Ambipolar diffusion in low-mass star formation. I. General comparison with the ideal MHD case
• The generation of strong magnetic fields during the formation of the first stars
• Importance of the Initial Conditions for Star Formation - I. Cloud Evolution and Morphology
• Modeling jet and outflow feedback during star cluster formation
• A robust numerical scheme for highly compressible magnetohydrodynamics: Nonlinear stability, implementation and tests
• Modelling CO formation in the turbulent interstellar medium
• The COMPLETE Survey of Outflows in Perseus
• Magnetic Braking and Protostellar Disk Formation: Ambipolar Diffusion
• Collapse of a molecular cloud core to stellar densities: stellar core and outflow formation in radiation magnetohydrodynamics simulations
• A Direct Multigrid Poisson Solver for Oct-Tree Adaptive Meshes
• The Small-Scale Dynamo and Non-Ideal MHD in Primordial Star Formation
• Star formation in metal-poor gas clouds
• Turbulence-induced disc formation in strongly magnetised cloud cores
• Zoom-Simulations of Protoplanetary Disks starting from GMC scales
• Radiation Feedback and Fragmentation in Massive Protostellar Cores
• Disc formation in turbulent massive cores: Circumventing the magnetic braking catastrophe
• Protostellar birth with ambipolar and ohmic diffusion
• Episodic accretion: the interplay of infall and disc instabilities
• Algorithmic comparisons of decaying, isothermal, supersonic turbulence
• The Episodic, Precessing Giant Molecular Outflow from IRAS 04239+2436 (HH 300)
• The role of magnetic fields in the formation of protostellar discs
• The stellar IMF from Isothermal MHD Turbulence
• The Jeans Mass as a Fundamental Measure of Self-Gravitating Disc Fragmentation and Initial Fragment Mass
• Formation and Evolution of Disks around Young Stellar Objects
• Rapid Evolution of Volatile CO from the Protostellar Disk Stage to the Protoplanetary Disk Stage
• Protoplanetary Disk Sizes and Angular Momentum Transport
• The Bridge: a transient phenomenon of forming stellar multiples
• Magneto-Hydrodynamics of Population III Star Formation
• Implementation of Sink Particles in the Athena Code
• The Star Formation Rate of Molecular Clouds
• The Self-gravitating Gas Fraction and The Critical Density for Star Formation
• Magnetic Fields in the Formation of the First Stars. I. Theory vs. Simulation
• Magnetic field amplification in accretion discs around the first stars: implications for the primordial IMF
• Protoplanetary disk birth in massive star forming clumps: the essential role of the magnetic field
• Resolving high Reynolds numbers in SPH simulations of subsonic turbulence
• Protostellar collapse: A comparison between SPH and AMR calculations
• JWST/MIRI Spectroscopy of the Disk of the Young Eruptive Star EX Lup in Quiescence
• Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer II. The formation of a 25 solar-mass star
• Molecular Outflows Identified in the FCRAO CO Survey of the Taurus Molecular Cloud
• Entrainment Mechanisms for Outflows in the L1551 Star-Forming Region
• The IMF and multiplicity of stars from gravity, turbulence, magnetic fields, radiation and outflow feedback
• Is the spiral morphology of the Elias 2-27 circumstellar disc due to gravitational instability?
• Magnetic field fluctuations in anisotropic, supersonic turbulence
• Binary Star Formation and the Outflows from their Discs
• A bright inner disk and structures in the transition disk around the very low-mass star CIDA 1
• Spiral structures in gravito-turbulent gaseous disks
• The role of initial magnetic field structure in the launching of protostellar jets
• The role of the turbulence driving mode for the Initial Mass Function
• Hydrodynamical simulations of the decay of high-speed molecular turbulence. II. Divergence from isothermality
• VETTAM: A scheme for radiation hydrodynamics with adaptive mesh refinement using the variable Eddington tensor method
• Testing the Turbulent Origin of the Stellar Initial Mass Function
• Implementation of stellar heating feedback in simulations of star cluster formation: effects on the initial mass function
• The role of turbulence during the formation of circumbinary discs
• Centrifugally driven winds from protostellar accretion discs. I - Formulation and initial results
• Non-ideal MHD simulations of subcritical prestellar cores with non-equilibrium chemistry
• Ionization degree and magnetic diffusivity in the primordial star-forming clouds
• Non-ideal magnetohydrodynamic simulations of the first star formation: the effect of ambipolar diffusion
• Numerical viscosity and resistivity in MHD turbulence simulations
• Massive Prestellar Cores in Radiation-magneto-turbulent Simulations of Molecular Clouds
• Protostellar spin-up and fast rotator formation through binary star formation
• Protostellar disks in their natural habitat -- the formation of protostars and their accretion disks in the turbulent and magnetized interstellar medium

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