Formation and Evolution of Disks Around Young Stellar Objects

Zhao, Bo; Tomida, Kengo; Hennebelle, P.; Tobin, John J.; Maury, A.; Hirota, Tomoya; Sánchez-Monge, Á.; Kuiper, Rolf; Rosen, Anna L.; Bhandare, Asmita; Padovani, M.; Lee, Yueh-Ning

doi:10.1007/s11214-020-00664-z

Cited by 78 publications

(59 citation statements)

References 265 publications

(385 reference statements)

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“…This has been robustly demonstrated in the inner disk regions in both local Bai 2013Bai , 2014Lesur et al 2014) and global simulations (Gressel et al 2015;Bai 2017;Wang et al 2019;Gressel et al 2020), where all three non-ideal MHD effects are relevant and dominate in different vertical heights. As a prerequisite, disk winds requires the disk be threaded by net vertical magnetic flux, which is likely inherited from the star formation process (see, e.g., Zhao et al 2020 for a review). The efficiency of angular momentum transport is then directly linked to the amount of magnetic flux threading the disk.…”

Section: Angular Momentum Transportmentioning

confidence: 99%

Global three-dimensional simulations of outer protoplanetary discs with ambipolar diffusion

Cui

Bai

2021

Monthly Notices of the Royal Astronomical Society

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The structure and evolution of protoplanetary disks (PPDs) are largely governed by disk angular momentum transport, mediated by magnetic fields. In the most observable outer disk, ambipolar diffusion is the primary non-ideal magnetohydrodynamic(MHD) effect. In this work, we study the gas dynamics in outer PPDs by conducting a series of global 3D non-ideal MHD simulations with ambipolar diffusion and net poloidal magnetic flux, using the Athena++ MHD code, with resolution comparable to local simulations. Our simulations demonstrate the co-existence of magnetized disk winds and turbulence driven by the magneto-rotational instability (MRI). While MHD winds dominate disk angular momentum transport, the MRI turbulence also contributes significantly. We observe that magnetic flux spontaneously concentrate into axisymmetric flux sheets, leading to radial variations in turbulence levels, stresses, and accretion rates. Annular substructures arise as a natural consequence of magnetic flux concentration. The flux concentration phenomena show diverse properties with different levels of disk magnetization and ambipolar diffusion. The disk generally loses magnetic flux over time, though flux sheets could prevent the leak of magnetic flux in some cases. Our results demonstrate the ubiquity of disk annular substructures in weakly MRI turbulent outer PPDs, and imply a stochastic nature of disk evolution.

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Section: Angular Momentum Transportmentioning

confidence: 99%

Global three-dimensional simulations of outer protoplanetary discs with ambipolar diffusion

Cui

Bai

2021

Monthly Notices of the Royal Astronomical Society

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“…In ideal MHD models, B fields are shown to strongly regulate the transport of angular momentum and hence modify the final properties of stars and disks (see Hennebelle & Inutsuka 2019;Wurster & Li 2018;Zhao et al 2020, and references therein). The inclusion of more realistic non-ideal MHD effects changed this view, with finer effects which may play a crucial role regarding the ability of B to interplay with gas kinematics, such as ionization and dust properties (Zhao et al 2018).…”

Section: Consistency With Predictions From Mhd Simulationsmentioning

confidence: 99%

“…Most of the final stellar mass is collected during a short but vigorous accretion phase. During this so-called protostellar phase, the star forms at the center of an infalling-rotating core, concomitantly with a surrounding disk of gas in circular orbits around the star: while the star will inherit from the majority of the accreted mass, most of the angular momentum contained in the protostellar envelope is expected to be expelled or stored in the protostellar disk, which evolution will eventually lead to protoplanetary systems (Zhao et al 2020). Class 0 objects are the youngest accreting protostars, surrounded by a dense envelope accreted onto the central protostellar embryo during a short (t < 5 × 10 4 yr) accretion phase (André et al 2000;Evans et al 2009).…”

Section: Introductionmentioning

confidence: 99%

An observational correlation between magnetic field, angular momentum and fragmentation in the envelopes of Class 0 protostars?

Galametz

Maury

Girart

et al. 2020

A&A

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Aims. The main goal of the following analysis is to assess the potential role of magnetic fields in regulating the envelope rotation, the formation of disks and the fragmentation of Class 0 protostars in multiple systems. Methods. We use the Submillimeter Array to carry out observations of the dust polarized emission at 0.87 mm, in the envelopes of a large sample of 20 Class 0 protostars. We estimate the mean magnetic field orientation over the central 1000 au envelope scales to characterize the orientation of the main component of the organized magnetic field at the envelope scales in these embedded protostars. This direction is compared to that of the protostellar outflow in order to study the relation between their misalignment and the kinematics of the circumstellar gas. The latter is traced via velocity gradient observed in the molecular line emission (mainly N2H+) of the gas at intermediate envelope scales. Results. We discover a strong relationship between the misalignment of the magnetic field orientation with the outflow and the amount of angular momentum observed at similar scales in the protostellar envelope, revealing a potential link between the kinetic and the magnetic energy at envelope scales. The relation could be driven by favored B-misalignments in more dynamical envelopes or a dependence of the envelope dynamics with the large-scale B initial configuration. Comparing the trend with the presence of fragmentation, we observe that single sources are mostly associated with conditions of low angular momentum in the inner envelope and good alignment of the magnetic field with protostellar outflows, at intermediate scales. Our results suggest that the properties of the magnetic field in protostellar envelopes bear a tight relationship with the rotating-infalling gas directly involved in the star and disk formation: we find that it may not only influence the fragmentation of protostellar cores into multiple stellar systems, but also set the conditions establishing the pristine properties of planet-forming disks.

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“…However, progress is being made in understanding the accretion mechanism. With the growing observational evidence of disk-like structures around OB-type protostars (e.g., Kuiper et al 2011;Beuther et al 2012a;Boley et al 2013;Haemmerlé et al 2016;Ilee et al 2018;Csengeri et al 2018;Maud et al 2019;Beuther et al 2019;Zapata et al 2019;Goddi et al 2020;Zhao et al 2020), the picture and the role of accretion disks in the formation of massive stars is becoming increasingly clear, supporting the scenario that high-mass star formation is a scaled-up version of low-mass star formation involving disk accretion and molecular outflows (e.g. Beuther et al 2002;Duarte-Cabral et al 2013;Beltrán & de Wit 2016;Ilee et al 2018).…”

Section: Introductionmentioning

confidence: 96%

The SEDIGISM survey: A search for molecular outflows

Yang

Urquhart

Wyrowski

et al. 2022

A&A

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Context. The formation processes of massive stars are still unclear but a picture is emerging involving accretion disks and molecular outflows in what appears to be a scaled-up version of low-mass star formation. A census of outflow activity towards high-mass star-forming clumps in various evolutionary stages has the potential to shed light on high-mass star formation. Aims. We conducted an outflow survey towards ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) clumps, using SEDIGISM (structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) data and aimed to obtain a large sample of clumps exhibiting outflow activity in different evolutionary stages. Methods. We identify the high-velocity wings of the 13 CO lines, indicating outflow activity, toward ATLASGAL clumps by (1) extracting the simultaneously observed 13 CO (2 -1) and C 18 O (2 -1) spectra from SEDIGISM, and (2) subtracting Gaussian fits to the scaled C 18 O (core emission) from the 13 CO line after considering opacity broadening. Results. We have detected high-velocity gas towards 1192 clumps out of a total sample of 2052 corresponding to an overall detection rate of 58%. Outflow activity has been detected in the earliest (apparently) quiescent clumps (i.e., 70µm weak), to the most evolved H ii region stages i.e., 8µm bright with tracers of massive star formation. The detection rate increases as a function of evolution (quiescent=51%, protostellar=47%, YSO = 57%, UC H ii regions = 76%). Conclusions. Our sample is the largest outflow sample identified so far. The high-detection rate from this large sample is consistent with the results of similar studies reported in the literature and supports the scenario that outflows are a ubiquitous feature of highmass star formation. The lower detection rate in early evolutionary stages may be due to the fact that outflows in the early stages are weak and difficult to detect. We obtain a statistically significant sample of outflow clumps for every evolutionary stage, especially for outflow clumps in the earliest stage (i.e., 70 µm dark). The detections of outflows in the 70 µm-dark clumps suggest that the absence of 70 µm emission is not a robust indicator of starless/pre-stellar cores.

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Formation and Evolution of Disks Around Young Stellar Objects

Cited by 78 publications

References 265 publications

Global three-dimensional simulations of outer protoplanetary discs with ambipolar diffusion

Global three-dimensional simulations of outer protoplanetary discs with ambipolar diffusion

An observational correlation between magnetic field, angular momentum and fragmentation in the envelopes of Class 0 protostars?

The SEDIGISM survey: A search for molecular outflows

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