Collapse and Fragmentation of Magnetic Molecular Cloud Cores with the Enzo AMR MHD Code. II. Prolate and Oblate Cores

Abstract

We present the results of a large suite of three-dimensional (3D) models of the collapse of magnetic molecular cloud cores using the adaptive mesh refinement (AMR) code Enzo2.2 in the ideal magnetohydrodynamics (MHD) approximation. The cloud cores are initially either prolate or oblate, centrally condensed clouds with masses of 1.73 or 2.73 $M_{\odot }$, respectively. The radial density profiles are Gaussian, with central densities 20 times higher than boundary densities. A barotropic equation of state is used to represent the transition from low density, isothermal phases, to high density, optically thick phases. The initial magnetic field strength ranges from 6.3 to 100 $\mu$G, corresponding to clouds that are strongly to marginally supercritical, respectively, in terms of the mass to magnetic flux ratio. The magnetic field is initially uniform and aligned with the clouds' rotation axes, with initial ratios of rotational to gravitational energy ranging from $10^{-4}$ to 0.1. Two significantly different outcomes for collapse result: (1) formation of single protostars with spiral arms, and (2) fragmentation into multiple protostar systems. The transition between these two outcomes depends primarily on the initial magnetic field strength, with fragmentation occurring for mass to flux ratios greater than about 14 times the critical ratio for prolate clouds. Oblate clouds typically fragment into several times more clumps than prolate clouds. Multiple, rather than binary, system formation is the general rule in either case, suggesting that binary stars are primarily the result of the orbital dissolution of multiple protostar systems.

arXiv comment36 pages, 5 tables, 10 figures, ApJ, in press

References in corpus (54)

• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• A Multi-Code Analysis Toolkit for Astrophysical Simulation Data
• Modelling Accretion in Protobinary Systems
• Enzo: An Adaptive Mesh Refinement Code for Astrophysics
• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps
• The Effects of Radiative Transfer on Low-Mass Star Formation
• The Importance of Radiative Feedback for the Stellar Initial Mass Function
• The impact of magnetic fields on single and binary star formation
• Collapse of Rotating Magnetized Molecular Cloud Cores and Mass Outflows
• The thermodynamics of collapsing molecular cloud cores using smoothed particle hydrodynamics with radiative transfer
• Collapse, outflows and fragmentation of massive, turbulent and magnetized prestellar barotropic cores
• Mid-Infrared Extinction Mapping of Infrared Dark Clouds II. The Structure of Massive Starless Cores and Clumps
• SMA Observations of Class 0 Protostars: A High-Angular Resolution Survey of Protostellar Binary Systems
• Protostellar collapse: radiative and magnetic feedbacks on small scale fragmentation
• Collapse of a molecular cloud core to stellar densities: stellar core and outflow formation in radiation magnetohydrodynamics simulations
• Conditions for Circumstellar Disk Formation: Effects of Initial Conditions and Sink Treatment
• Does Magnetic Field-Rotation Misalignment Solve the Magnetic Braking Catastrophe in Protostellar Disk Formation?
• Rotationally-supported disks around Class I sources in Taurus: disk formation constraints
• Inefficient star formation: The combined effects of magnetic fields and radiative feedback
• The influence of turbulence during magnetized core collapse and its consequences on low-mass star formation
• Second Core Formation and High Speed Jets: Resistive MHD Nested Grid Simulations
• Alignment Between Flattened Protostellar Infall Envelopes and Ambient Magnetic Fields
• DR 21(OH): a highly fragmented, magnetized, turbulent dense core
• Cosmological AMR MHD with Enzo
• Collapse of a molecular cloud core to stellar densities: the formation and evolution of pre-stellar discs
• Magnetization of cloud cores and envelopes and other observational consequences of reconnection diffusion
• Relativistic Hydrodynamic Flows Using Spatial and Temporal Adaptive Structured Mesh Refinement
• Intrinsic Shapes of Molecular Cloud Cores
• Protostellar Disk Formation Enabled by Weak, Misaligned Magnetic Fields
• Implementation of Sink Particles in the Athena Code
• Protostellar Accretion Flows Destabilized by Magnetic Flux Redistribution
• An improved sink particle algorithm for SPH simulations
• Mass and Magnetic distributions in Self Gravitating Super Alfvenic Turbulence with AMR
• VLA and CARMA Observations of Protostars in the Cepheus Clouds: Sub-arcsecond Proto-Binaries Formed via Disk Fragmentation
• An Observed Lack of Substructure in Starless Cores
• Disc formation in turbulent cloud cores: is magnetic flux loss necessary to stop the magnetic braking catastrophe or not?
• Microlensing Discovery of a Population of Very Tight, Very Low-mass Binary Brown Dwarfs
• Simulating hydromagnetic processes in star formation: introducing ambipolar diffusion into an adaptive mesh refinement code
• An Explicit Scheme for Incorporating Ambipolar Diffusion in a Magnetohydrodynamics Code
• Magnetic Flux Expulsion in Star Formation
• Protostellar collapse and fragmentation using an MHD GADGET
• Formation and Early Evolution of Circumstellar Disks in Turbulent Molecular Cloud Cores
• Orbital and Mass Ratio Evolution of Protobinaries Driven by Magnetic Braking
• The Structure and Evolution of Magnetized Cloud Cores in a Zero--Density Background
• Collapse and Fragmentation of Magnetic Molecular Cloud Cores with the Enzo AMR MHD Code. I. Uniform Density Sphere
• Mapping the prestellar core Ophiuchus D (L1696A) in ammonia
• The intrinsic shapes of starless cores in Ophiuchus
• Collapse and Fragmentation of Molecular Cloud Cores. X. Magnetic Braking of Prolate and Oblate Cores
• Young starless cores embedded in the magnetically dominated Pipe Nebula. II. Extended dataset
• Collapse and Fragmentation of Molecular Cloud Cores. IX. Magnetic Braking of Initially Filamentary Clouds
• The Equilibrium Structure of Prolate Magnetized Molecular Cores

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