How does a protostar shed excess angular momentum during contraction?
Answer
Stellar winds and jets
The rapid spinning established during the initial gravitational collapse creates a rotational barrier around the equator, forming a protoplanetary disk where material has difficulty falling directly onto the core due to the conservation of angular momentum. To continue contracting and increase central density, the object must shed this rotational momentum. This shedding occurs primarily along the axis of rotation, where rotation speed is relatively lower. High-speed outflows of material, known as stellar winds and jets, are channeled out from the poles, clearing away the surrounding envelope. These powerful beams are often made visible when they impact nearby gas, forming conspicuous Herbig-Haro objects.
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