Emission from magnetized accretion disks around young stars.
TAPIA C. and LIZANO S.
Abstract (from CDS):
We calculate the emission of protoplanetary disks threaded by a poloidal magnetic field and irradiated by a central star. The radial structure of these disks was studied by Shu and collaborators and the vertical structure was studied by Lizano and collaborators. We consider disks around low-mass protostars (LMPs), T Tauri stars, and FU Ori stars with different mass-to-flux ratios λsys. We calculate the spectral energy distribution and the antenna temperature profiles at 1 and 7 mm convolved with the Atacama Large Millimeter/submillimeter Array (ALMA) and Very Large Array (VLA) beams. We find that disks with weaker magnetization (high values of λsys) emit more than disks with stronger magnetization (low values of λsys). This happens because the former are denser, hotter, and have larger aspect ratios, receiving more irradiation from the central star. The level of magnetization also affects the optical depth at millimeter wavelengths, being larger for disks with high λsys. In general, disks around LMP and T Tauri stars are optically thin at 7 mm, while disks around FU Ori are optically thick. A qualitative comparison of the emission of these magnetized disks, including heating by an external envelope, with the observed millimeter antenna temperature profiles of HL Tau indicates that large cm grains are required to increase the optical depth and reproduce the observed 7 mm emission at large radii.