Outflows and mass accretion in collapsing dense cores with misaligned rotation axis and magnetic field
Résumé
Outflows and jets are intimately related to the formation of stars, and play an important role in redistributing mass, energy and angular momentum within the dense core and parent cloud. The interplay between magnetic field and rotation is responsible for launching these outflows, whose formation has been generally carried out for idealized systems where the angle alpha between the rotation axis and large-scale magnetic field is zero. Here we explore, through three-dimensional ideal magnetohydrodynamic simulations, the effects of a non-zero alpha on the formation of outflows during the collapse of dense pre-stellar cores. We find that mass ejection is less efficient for increasing angle alpha and that outflows are essentially suppressed for alpha ~ 90°. An important consequence is a corresponding increase of the mass accreted on to the adiabatic (first) core. In addition, mean flow velocities tend to increase with alpha, and misaligned configurations produce clumpy, heterogeneous outflows that undergo precession, and are more prone to instabilities.