Emission from Magnetized Accretion Disks around Young Stars

Abstract

We calculate the emission of protoplanetary disks threaded by a poloidal magnetic field and irradiated by the 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, T Tauri stars, and FU Ori stars with different mass-to-flux ratios ${\lambda }_{\mathrm{sys}}$. We calculate the spectral energy distribution and the antenna temperature profiles at 1 mm and 7 mm convolved with the ALMA and VLA beams. We find that disks with weaker magnetization (high values of ${\lambda }_{\mathrm{sys}}$) emit more than disks with stronger magnetization (low values of ${\lambda }_{\mathrm{sys}}$). 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 ${\lambda }_{\mathrm{sys}}$. In general, disks around low mass protostars 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.

arXiv comment21 pages, 12 figures

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Cited by in corpus (4)

• The young protostellar disk in IRAS16293-2422 B is hot and shows signatures of gravitational instability
• Diagnosing 0.1-10 au scale morphology of the FU\,Ori disk using ALMA and VLTI/GRAVITY
• Migrating Planets into Ultra-Short-Period Orbits during Episodic Accretion Events
• Exploring the Grain Properties in the Disk of HL Tau with an Evolutionary Model