The collapse of a molecular cloud core to stellar densities using radiation non-ideal magnetohydrodynamics

Wurster, James; Bate, Matthew R.; Price, Daniel J.

doi:10.1093/mnras/stx3339

Cited by 62 publications

(86 citation statements)

References 82 publications

(156 reference statements)

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“…In agreement with our previous studies (e.g. Wurster et al 2016Wurster et al , 2018a, this indicates that non-ideal MHD processes only affect high-density (ρ 10 −12 g cm −3 ) gas.…”

Section: B Vs ρsupporting

confidence: 93%

There is no magnetic braking catastrophe: low-mass star cluster and protostellar disc formation with non-ideal magnetohydrodynamics

Wurster

Bate

Price

2019

Monthly Notices of the Royal Astronomical Society

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We present results from the first radiation non-ideal magnetohydrodynamics (MHD) simulations of low-mass star cluster formation that resolve the fragmentation process down to the opacity limit. We model 50 M turbulent clouds initially threaded by a uniform magnetic field with strengths of 3, 5 10 and 20 times the critical mass-to-magnetic flux ratio, and at each strength, we model both an ideal and non-ideal (including Ohmic resistivity, ambipolar diffusion and the Hall effect) MHD cloud. Turbulence and magnetic fields shape the large-scale structure of the cloud, and similar structures form regardless of whether ideal or non-ideal MHD is employed. At high densities (10 6 n H 10 11 cm −3 ), all models have a similar magnetic field strength versus density relation, suggesting that the field strength in dense cores is independent of the large-scale environment. Albeit with limited statistics, we find no evidence for the dependence of the initial mass function on the initial magnetic field strength, however, the star formation rate decreases for models with increasing initial field strengths; the exception is the strongest field case where collapse occurs primarily along field lines. Protostellar discs with radii 20 au form in all models, suggesting that disc formation is dependent on the gas turbulence rather than on magnetic field strength. We find no evidence for the magnetic braking catastrophe, and find that magnetic fields do not hinder the formation of protostellar discs.

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“…In agreement with our previous studies (e.g. Wurster et al 2016Wurster et al , 2018a, this indicates that non-ideal MHD processes only affect high-density (ρ 10 −12 g cm −3 ) gas.…”

Section: B Vs ρsupporting

confidence: 93%

There is no magnetic braking catastrophe: low-mass star cluster and protostellar disc formation with non-ideal magnetohydrodynamics

Wurster

Bate

Price

2019

Monthly Notices of the Royal Astronomical Society

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“…Thus we conclude that the turbulence in the molecular cloud core may not create a counter-rotating envelope. Rather, the magnetic field in the molecular cloud core may create it (e.g., Krasnopolsky et al 2011;Li et al 2011;Tsukamoto et al 2015c;Wurster et al 2016;Tsukamoto et al 2017;Wurster et al 2017Wurster et al , 2018Wurster & Bate 2019).…”

Section: Envelope Rotation Structurementioning

confidence: 99%

Star–disc alignment in the protoplanetary discs: SPH simulation of the collapse of turbulent molecular cloud cores

Takaishi

Tsukamoto

Suto

2020

Monthly Notices of the Royal Astronomical Society

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We perform a series of three-dimensional smoothed particle hydrodynamics (SPH) simulations to study the evolution of the angle between the protostellar spin and the protoplanetary disk rotation axes (the star-disk angle ψ sd ) in turbulent molecular cloud cores. While ψ sd at the protostar formation epoch exhibits broad distribution up to ∼ 130 • , ψ sd decreases ( 20 • ) in a timescale of ∼ 10 4 yr. This timescale of the star-disk alignment, t alignment , corresponds basically to the mass doubling time of the central protostar, in which the protostar forgets its initial spin direction due to the mass accretion from the disk. Values of ψ sd both at t = 10 2 yr and t = 10 5 yr after the protostar formation are independent of the ratios of thermal and turbulent energies to gravitational energy of the initial cloud cores: α = E thermal /|E gravity | and γ turb = E turbulence /|E gravity |. We also find that a warped disk is possibly formed by the turbulent accretion flow from the circumstellar envelope.

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“…In the studies where the coefficients are calculated at runtime (e.g. Wurster et al 2016Wurster et al , 2017Wurster et al , 2018a, only a few elements and reactions are calculated -too few to allow a meaningful comparison to observations.…”

Section: Introductionmentioning

confidence: 99%

Ambipolar diffusion and the molecular abundances in pre-stellar cores

Priestley

Wurster

Viti

2019

Monthly Notices of the Royal Astronomical Society

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We investigate differences in the molecular abundances between magnetically superand sub-critical prestellar cores, performing three-dimensional non-ideal magnetohydrodynamical (MHD) simulations with varying densities and magnetic field strengths, and post-processing the results with a time-dependent gas-grain chemical code. Most molecular species show significantly more central depletion in subcritical models, due to the longer duration of collapse. However, the directly observable quantities -the molecule to hydrogen column density ratios -are generally too similar for observational data to discriminate between models. The profiles of N 2 H + and HCO + show qualitative differences between supercritical and subcritical models on scales of 0.01 pc, which may allow the two cases to be distinguished. However, this requires knowledge of the hydrogen column density, which is not directly measureable, and predicted line intensity profiles from radiative transfer modelling are similar for these molecules. Other commonly observed species, such as HCN and CH 3 OH, have line intensity profiles which differ more strongly between models, and so are more promising as tracers of the mechanism of cloud collapse.

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The collapse of a molecular cloud core to stellar densities using radiation non-ideal magnetohydrodynamics

Cited by 62 publications

References 82 publications

There is no magnetic braking catastrophe: low-mass star cluster and protostellar disc formation with non-ideal magnetohydrodynamics

There is no magnetic braking catastrophe: low-mass star cluster and protostellar disc formation with non-ideal magnetohydrodynamics

Star–disc alignment in the protoplanetary discs: SPH simulation of the collapse of turbulent molecular cloud cores

Ambipolar diffusion and the molecular abundances in pre-stellar cores

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