Magnetic fields during the early stages of massive star formation - II. A generalised outflow criterion

Abstract

Numerical simulations of outflows formed during the collapse of 100 M_sun cloud cores are presented. We derive a generalised criterion from MHD wind theory to analyse the launching mechanism of these outflows. The criterion is successfully applied to the whole outflow structure and cases with sub-Keplerian disc rotation. It allows us to decide whether an outflow is driven centrifugally or by the toroidal magnetic pressure. We show that quantities such as the magnetic field line inclination or the ratio of the toroidal to poloidal magnetic field alone are insufficient to determine the driving mechanism of outflows. By performing 12 runs we are able to study the influence of the initial conditions on the properties of outflows around massive protostars in detail. Our simulations reveal a strong effect of the magnetic field strength on the outflow morphology. In runs with weak fields or high rotational energies, well collimated, fast jets are observed whereas for strong fields poorly collimated, low-velocity outflows are found. We show that the occurrence of a fast jet is coupled to the existence of a Keplerian protostellar disc. Despite the very different morphologies all outflows are launched from the discs by centrifugal acceleration with the toroidal magnetic field increasingly contributing to the gas acceleration further away from the discs. The poor collimation of the outflows in runs with strong fields is a consequence of the weak hoop stresses. This in turn is caused by the slow build-up of a toroidal field due to sub-Keplerian disc rotation. The mass ejection/accretion ratios scatter around a mean of 0.3 in accordance with observational and analytical results. We suggest an evolutionary scenario for the earliest stage of massive star formation in which initially poorly collimated outflows develop which progressively get better collimated due to the generation of fast jets.

22 pages, 15 figures, accepted by MNRAS, updated to final version

References in corpus (15)

• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Magnetic processes in a collapsing dense core. I Accretion and Ejection
• Magnetic Braking and Protostellar Disk Formation: The Ideal MHD Limit
• Collapse, outflows and fragmentation of massive, turbulent and magnetized prestellar barotropic cores
• Nonideal MHD Effects and Magnetic Braking Catastrophe in Protostellar Disk Formation
• A robust numerical scheme for highly compressible magnetohydrodynamics: Nonlinear stability, implementation and tests
• Magnetic fields during the early stages of massive star formation - I. Accretion and disk evolution
• Radiation-Hydrodynamic Simulations of Massive Star Formation with Protostellar Outflows
• Radiation Magnetohydrodynamics Simulation of Proto-Stellar Collapse: Two-Component Molecular Outflow
• Supersonic turbulence, filamentary accretion,and the rapid assembly of massive stars and disks
• Jet formation from massive young stars: Magnetohydrodynamics versus radiation pressure
• Molecular outflows and hot molecular core in G24.78+0.08 at sub-arcsecond angular resolution
• A bipolar outflow from the massive protostellar core W51e2-E
• Outflow activities in the young high-mass stellar object G23.44-0.18
• High Resolution CO Observations of Massive Star Forming Regions

Cited by in corpus (74)

• The Star Formation Rate of Turbulent Magnetized Clouds: Comparing Theory, Simulations, and Observations
• Super-Massive Stars as a Source of Abundance Anomalies of Proton-Capture Elements in Globular Clusters
• The SILCC (SImulating the LifeCycle of molecular Clouds) project - II. Dynamical evolution of the supernova-driven ISM and the launching of outflows
• Modeling jet and outflow feedback during star cluster formation
• Evolution of Protostellar Outflow around Low-mass Protostar
• Conditions for Circumstellar Disk Formation: Effects of Initial Conditions and Sink Treatment
• CO outflows from high-mass Class 0 protostars in Cygnus-X
• First hydrodynamics simulations of radiation forces and photoionization feedback in massive star formation
• Zoom-Simulations of Protoplanetary Disks starting from GMC scales
• Magnetic Fields in Astrophysical Jets: From Launch to Termination
• A search for ionized jets towards massive young stellar objects
• Forming spectroscopic massive proto-binaries by disk fragmentation
• Simulating the Formation of Massive Protostars: I. Radiative Feedback and Accretion Disks
• Impact of Protostellar Outflows on Turbulence and Star Formation Efficiency in Magnetized Dense Cores
• STARFORGE: The effects of protostellar outflows on the IMF
• Physical Processes in Star Formation
• Collimated jets from the first core
• Protostellar Outflows and Radiative Feedback from Massive Stars
• The SILCC project - V. The impact of magnetic fields on the chemistry and the formation of molecular clouds
• Massive Outflows Driven by Magnetic Effects in Star Forming Clouds with High Mass Accretion Rates
• Protostellar Jets Enclosed by Low-velocity Outflows
• Jets and outflows of massive protostars - From cloud collapse to jet launching and cloud dispersal
• Observing the onset of outflow collimation in a massive protostar
• From Poloidal to Toroidal: Detection of Well-ordered Magnetic Field in High-mass Proto-cluster G35.2-0.74N
• The IMF and multiplicity of stars from gravity, turbulence, magnetic fields, radiation and outflow feedback
• Dynamical Evidence for a Magnetocentrifugal Wind from a 20 Msun Binary Young Stellar Object
• Synthetic Observations of Magnetic Fields in Protostellar Cores
• A Very Compact Extremely High Velocity Flow toward MMS 5 / OMC-3 Revealed with ALMA
• Misalignment of Magnetic Fields, Outflows and Discs in Star-forming Clouds
• Radiation Transfer of Models of Massive Star Formation. II. Effects of the Outflow
• Velocity and magnetic fields within 1000 AU from a massive YSO
• Protostellar Outflows at the EarliesT Stages (POETS). II. A possible radio synchrotron jet associated with the EGO G035.02+0.35
• Massive Outflows Driven by Magnetic Effects II: Comparison with Observations
• The Interplay between Ambipolar Diffusion and Hall Effect on Magnetic Field Decoupling and Protostellar Disc Formation
• The origin of dust polarization in molecular outflows
• The contribution of binary star formation via core-fragmentation on protostellar multiplicity
• The relation between accretion rates and the initial mass function in hydrodynamical simulations of star formation
• Collapse of turbulent massive cores with ambipolar diffusion and hybrid radiative transfer II. Outflows
• Failed and delayed protostellar outflows with high mass accretion rates
• Measuring the ionisation fraction in a jet from a massive protostar
• A Protostellar Jet Emanating from a Hypercompact HII Region
• EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions III. The flux-limited sample
• Are molecular outflows around high-mass stars driven by ionization feedback?
• Deuterium fractionation and H2D+ evolution in turbulent and magnetized cloud cores
• The role of the turbulence driving mode for the Initial Mass Function
• Protostellar Outflows at the EarliesT Stages (POETS). III. H2O masers tracing disk-winds and jets near luminous YSOs
• Rapidly increasing collimation and magnetic field changes of a H2O maser outflow
• Modeling disks and magnetic outflows around a forming massive star: II. Dynamics of jets from massive protostars
• EVN observations of 6.7-GHz methanol maser polarization in massive star-forming regions II. First statistical results
• Non-ideal magnetohydrodynamics on a moving mesh
• Evolution of the Water Maser Expanding Shell in W75N VLA 2
• Accelerating a water maser face-on jet from a high mass young stellar object
• CO multi-line observations of HH 80-81: a two-component molecular outflow associated with the largest protostellar jet in our Galaxy
• Disk wind feedback from high-mass protostars
• EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions IV. Magnetic field strength limits and structure for 7 additional sources
• MHD simulations of the formation and propagation of protostellar jets to observational length scales
• The impact of episodic outflow feedback on stellar multiplicity and the star formation efficiency
• Growth of Magnetorotational Instability in Circumstellar Disks around Class 0 Protostars
• The magnetic field at milliarcsecond resolution around IRAS20126+4104
• A turbulent origin for the complex envelope kinematics in the young low-mass core Per-Bolo 58
• Structure, Dynamics and Deuterium Fractionation of Massive Pre-Stellar Cores
• Isolated Massive Star Formation in G28.20-0.05
• [Fe II] 1.64 um Features of Jets and Outflows from Young Stellar Objects in the Carina Nebula
• EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions. V. Completion of the flux-limited sample
• Predictions for Observing Protostellar Outflows with ALMA
• Morphologies of protostellar outflows: An ALMA view
• Candidate Young Stellar Objects in the S-cluster: The Kinematic Analysis of a Sub-population of the Low-mass G-objects close to Sgr A*
• Protostellar disk accretion in turbulent filaments
• Turbulence and its connection to episodic accretion in binary YSOs
• The magnetic field of a magnetohydrodynamic disk wind: Water maser observations and simulations
• Magnetic Fields and Star Formation
• Can High-velocity Protostellar Jets Help to Drive Low-velocity Outflow?
• Characterising the high-mass star forming region IRAS 18144-1723 through methanol maser observations
• Discs and outflows in the early phases of massive star formation: influence of magnetic fields and ambipolar diffusion