Observational signatures of early disk formation by MHD models
Exploring protostellar disk formation via misaligned rotation axes and magnetic field, and their observable features. The streamlines on the column density maps show the direction of flows along the picture frame. The black lines over Stokes Q and U parameters depict the direction of magnetic field estimated from the polarization angles. We predict that we witness magnetically directed spiraling behavior by polarization observations (Väisälä et al. 2019).
Predicting diagnostic observational signatures produced by magnetohydrodynamical (MHD) models is essential in understanding the physics for the formation of protostellar disks in the ALMA era. With a radiative transfer code “Perspective”, we explored time evolution of porto-stellar disk, most of which have 90-degree misalignment between the rotational axis and the magnetic field (Väisälä, Shang, Krasnopolsky et al. 2019). Four visible object types can be characterized, origins of which are dependent on the initial conditions. Our results showed complex spiraling density, velocity and polarization structures. We suggested that spiraling pseudo-disk structures could function as an effective observation signature of the formation process. We also argue that we witness accretion in the disk with eccentric orbits which appear as spiral-like perturbation from simple circular Keplerian orbits.