Abstract Misalignment between rotation and magnetic fields has been suggested to be one type of physical mechanism that can ease the effects of magnetic braking during the collapse of cloud cores leading to the formation of protostellar disks. However, its essential factors are poorly understood. Therefore, we perform a more detailed analysis of the physics involved. We analyze existing simulation data to measure the system torques, mass accretion rates, and Toomre Q parameters. We also examine the presence of shocks in the system. While advective torques are generally the strongest, we find that magnetic and gravitational torques can play substantial roles in how angular momentum is transferred during the disk formation process. Magnetic torques can shape the accretion flows, creating two-armed magnetized inflow spirals aligned with the magnetic field. We find evidence of an accretion shock that is aligned according to the spiral structure of the system. Inclusion of ambipolar diffusion as explored in this work has shown a slight influence in the small-scale structures but not in the main morphology. We discuss potential candidate systems where some of these phenomena could be present.
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This content will become publicly available on July 1, 2025
Early Planet Formation in Embedded Disks (eDisk). XV. Influence of Magnetic Field Morphology in Dense Cores on Sizes of Protostellar Disks
The magnetic field of a molecular cloud core may play a role in the formation of circumstellar disks in the core. We present magnetic field morphologies in protostellar cores of 16 targets in the Atacama Large Millimeter/submillimeter Array large program “Early Planet Formation in Embedded Disks (eDisk),” which resolved their disks with 7 au resolutions. The 0.1 pc scale magnetic field morphologies were inferred from the James Clerk Maxwell Telescope POL-2 observations. The mean orientations and angular dispersions of the magnetic fields in the dense cores are measured and compared with the radii of the 1.3 mm continuum disks and the dynamically determined protostellar masses from the eDisk program. We observe a significant correlation between the disk radii and the stellar masses. We do not find any statistically significant dependence of the disk radii on the projected misalignment angles between the rotational axes of the disks and the magnetic fields in the dense cores, nor on the angular dispersions of the magnetic fields within these cores. However, when considering the projection effect, we cannot rule out a positive correlation between disk radii and misalignment angles in three-dimensional space. Our results suggest that the morphologies of magnetic fields in dense cores do not play a dominant role in the disk formation process. Instead, the sizes of protostellar disks may be more strongly affected by the amount of mass that has been accreted onto star+disk systems, and possibly other parameters, for example, magnetic field strength, core rotation, and magnetic diffusivity.
more » « less- PAR ID:
- 10531768
- Publisher / Repository:
- Astrophysical Journal
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 969
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 125
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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