The Effect of Misalignment between Rotation Axis and Magnetic Field on Circumstellar Disk

The formation of circumstellar disks is investigated using three-dimensional resistive magnetohydrodynamic simulations, in which the initial prestellar cloud has a misaligned rotation axis with respect to the magnetic field. We examine the effects of (i) the initial angle difference between the global magnetic field and the cloud rotation axis ($θ_0$) and (ii) the ratio of the thermal to gravitational energy ($α_0$). We study $16$ models in total and calculate the cloud evolution until $\sim \! 5000$ yr after protostar formation. Our simulation results indicate that an initial non-zero $θ_0$ ($> 0$) promotes the disk formation but tends to suppress the outflow driving, for models that are moderately gravitationally unstable, $α_0 \lesssim 1$. In these models, a large-sized rotationally-supported disk forms and a weak outflow appears, in contrast to a smaller disk and strong outflow in the aligned case ($θ_0 = 0$). Furthermore, we find that when the initial cloud is highly unstable with small $α_0$, the initial angle difference $θ_0$ does not significantly affect the disk formation and outflow driving.

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