Influence of Magnetic Field Morphology in Dense Cores on Sizes of Protostellar Disks

Hsi-Wei Yen^1*, Jinshi Sai¹, Jonathan P. Williams², Patrick M. Koch¹, Nagayoshi Ohashi¹, and the eDisk team³

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
²Institute for Astronomy, University of Hawaii, Honolulu, Hawaii, USA
³35 members, from 17 institutes, worldwide including, Taiwan

* Presenter:Hsi-Wei Yen, email:hwyen@asiaa.sinica.edu.tw

Protoplanetary disks around young stars are sites of planet formation, and the planet formation process is closely related to the formation and evolution of these disks. The physical mechanisms controlling the disk formation and evolution remain observationally unclear. In this presentation, we will present the magnetic field structures in the protostellar dense cores on a 0.1 pc scale inferred from polarization observations with the James Clerk Maxwell Telescope (JCMT) POL-2 instrument of 16 targets from the Atacama Large Millimeter/submillimeter Array large program ``Early Planet Formation in Embedded Disks (eDisk).'' We measure the mean orientations and angular dispersions of the magnetic fields in the dense cores, and compare them 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, and 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 definitively rule out a positive correlation between disk radii and misalignment angles in three-dimensional space. Our results suggest that the orientations and structures 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.

Keywords: Star formation, Circumstellar disks, Interstellar magnetic fields , Protostars, Star forming regions