Magnetic Braking and Protostellar Disk Formation: The Ideal MHD Limit

Mellon, Richard R.; Li, Zhi-Yun

doi:10.1086/587542

Cited by 250 publications

(335 citation statements)

References 65 publications

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“…In previous works which argue that the disc formation is strongly suppressed by the magnetic braking (e.g., Mellon & Li 2008;Li, Krasnopolsky & Shang 2011), the inner boundary was set from the beginning of the simulations. With this treatment, the previous works cannot follow the first core phase properly that should be supported by gas pressure.…”

Section: Summary and Discussionmentioning

confidence: 99%

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Effects of Ohmic and ambipolar diffusion on formation and evolution of first cores, protostars, and circumstellar discs

Tsukamoto

Iwasaki

Okuzumi

et al. 2015

Mon. Not. R. Astron. Soc.

125

116

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We investigate the formation and evolution of a first core, protostar, and circumstellar disc with a three-dimensional non-ideal (including both Ohmic and ambipolar diffusion) radiation magnetohydrodynamics simulation. We found that the magnetic flux is largely removed by magnetic diffusion in the first core phase and that the plasma β of the centre of the first core becomes large, β > 10 4 . Thus, proper treatment of first core phase is crucial in investigating the formation of protostar and disc. On the other hand, in an ideal simulation, β ∼ 10 at the centre of the first core. The simulations with magnetic diffusion show that the circumstellar disc forms at almost the same time of protostar formation even with a relatively strong initial magnetic field (the value for the initial mass-to-flux ratio of the cloud core relative to the critical value is µ = 4). The disc has a radius of r ∼ 1 AU at the protostar formation epoch. We confirm that the disc is rotationally supported. We also show that the disc is massive (Q ∼ 1) and that gravitational instability may play an important role in the subsequent disc evolution.

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Section: Summary and Discussionmentioning

confidence: 99%

“…In the simulations of Mellon & Li (2008) and Li, Krasnopolsky & Shang (2011), the inner boundary or sink is set from the beginning of the simulations. In such a set-up, the simulations cannot follow the evolution of a first core which is mainly supported by gas pressure and not necessarily by rotation.…”

Section: Introductionmentioning

confidence: 99%

Effects of Ohmic and ambipolar diffusion on formation and evolution of first cores, protostars, and circumstellar discs

Tsukamoto

Iwasaki

Okuzumi

et al. 2015

Mon. Not. R. Astron. Soc.

125

116

View full text Add to dashboard Cite

show abstract

“…They are likely forming disks as material from the envelope is funneled onto the protostar (Ulrich 1976;Terebey et al 1984). It is not clear whether these sources have rotationally supported disks, or whether magnetic braking at these early ages inhibits disk formation (e.g., Allen et al 2003;Mellon & Li 2008;Li et al 2013). Rotationally supported disks have been observed around some Class 0 protostars (Tobin et al 2012(Tobin et al , 2013Murillo et al 2013;Codella et al 2014;Lindberg et al 2014;Aso et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Sheehan

Eisner

2017

ApJ

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Class I protostars are thought to represent an early stage in the lifetime of protoplanetary disks, when they are still embedded in their natal envelope. Here we measure the disk masses of 10 Class I protostars in the Taurus Molecular Cloud to constrain the initial mass budget for forming planets in disks. We use radiative transfer modeling to produce synthetic protostar observations and fit the models to a multi-wavelength data set using a Markov Chain Monte Carlo fitting procedure. We fit these models simultaneously to our new Combined Array for Research in Millimeter-wave Astronomy 1.3 mm observations that are sensitive to the wide range of spatial scales that are expected from protostellar disks and envelopes so as to be able to distinguish each component, as well as broadband spectral energy distributions compiled from the literature. We find a median disk mass of  M 0.018 on average, more massive than the Taurus Class II disks, which have median disk mass of~ M 0.0025 . This decrease in disk mass can be explained if dust grains have grown by a factor of 75 in grain size, indicating that by the Class II stage, at a few Myr, a significant amount of dust grain processing has occurred. However, there is evidence that significant dust processing has occurred even during the Class I stage, so it is likely that the initial mass budget is higher than the value quoted here.

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“…For example, while Mellon & Li (2008) estimate that the value of μ, below which disks do not form, is larger than 10, Price & Bate (2007) and HF08 find that this occurs when μ < 5−10. A broad distribution of μ has been inferred from observations, but most cores have magnetic fields corresponding to values of μ typically smaller than 5 (Crutcher 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Magnetohydrodynamic (MHD) simulations (e.g., Machida et al 2005;Banerjee & Pudritz 2006) find that even for modest values of the magnetic intensity, disk formation can be suppressed by magnetic braking (Shu et al 1987;Mouschovias 1991;Basu & Mouschovias 1995;Galli et al 2006) which transports angular momentum from the inner parts of the cloud towards its outer regions (Allen et al 2003;Fromang et al 2006;Price & Bate 2007;Hennebelle & Fromang 2008, hereafter HF08;Mellon & Li 2008, 2009). …”

Section: Introductionmentioning

confidence: 99%

Disk formation during collapse of magnetized protostellar cores

Hennebelle¹,

Ciardi

2009

A&A

224

255

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Context. In the context of star and planet formation, understanding the formation of disks is of fundamental importance. Aims. Previous studies found that the magnetic field has a very strong impact on the collapse of a prestellar cloud, by possibly suppressing the formation of a disk even for relatively modest values of the magnetic intensity. Since observations infer that cores have a substantial level of magnetization, this raises the question of how disks form. However, most studies have been restricted to the case in which the initial angle, α, between the magnetic field and the rotation axis equals 0 • . Here we explore and analyse the influence of non aligned configurations on disk formation. Methods. We perform 3D ideal MHD, AMR numerical simulations for various values of μ, the ratio of the mass-to-flux to the critical mass-to-flux, and various values of α. Results. We find that disks form more easily as α increases from 0 to 90 • . We propose that as the magnetized pseudo-disks become thicker with increasing α, the magnetic braking efficiency is lowered. We also find that even small values of α ( 10-20 • ) show significant differences with the aligned case. Conclusions. Within the framework of ideal MHD, and for our choice of initial conditions, centrifugally supported disks cannot form for values of μ smaller than 3 when the magnetic field and the rotation axis are perpendicular, and smaller than about 5-10 when they are perfectly aligned.

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Magnetic Braking and Protostellar Disk Formation: The Ideal MHD Limit

Cited by 250 publications

References 65 publications

Effects of Ohmic and ambipolar diffusion on formation and evolution of first cores, protostars, and circumstellar discs

Effects of Ohmic and ambipolar diffusion on formation and evolution of first cores, protostars, and circumstellar discs

Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud

Disk formation during collapse of magnetized protostellar cores

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