Stellar Nebulae and angular momentum

[mateomy]

Maybe this is a simple question but, all the stuff I've been reading so far keeps talking about protostars and their angular momentum being a consequence of the surrounding nebula. Why do they inherit that in the first place? Is is just a consequence of the gravitational collapse?

 

[Drakkith]

In a collapsing gas cloud it is practically impossible for it not to have net angular momentum during/after the collapse.

 

[Martinaston]

It has to be due to an outside influance, so all nebule must be linked in some way.

 

[Drakkith]

It has to be due to an outside influance, so all nebule must be linked in some way.

What is your justification for this?

 

[pmacias]

The angular momentum of a protostar is indeed a consequence of the surrounding nebula and its gravitational collapse. As the nebula collapses, it begins to spin faster due to conservation of angular momentum, which is a fundamental law of physics. This means that as the nebula contracts and becomes smaller, its rotation rate increases.

The reason for this increase in rotation rate is the distribution of mass within the nebula. As the nebula collapses, it becomes more compact and the mass is distributed closer to the center. This results in a decrease in the moment of inertia, which is a measure of how much an object resists rotation. As the moment of inertia decreases, the rotation rate must increase in order to conserve angular momentum.

Therefore, the protostar inherits its angular momentum from the initial rotation of the stellar nebula, which is a remnant of the rotation of the molecular cloud from which it formed. This rotation is often caused by turbulence and random motions within the cloud.

Overall, the angular momentum of a protostar is a crucial factor in its formation and evolution. It plays a significant role in shaping the structure and dynamics of the protostar, and ultimately determines its final mass, size, and rotation rate. Further research is still needed to fully understand the detailed processes involved in the transfer of angular momentum from the stellar nebula to the protostar.