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Excuse my poor English, I have a lot to learn.

Should we imagine a particle falling directly to the center without an orbit like an apple falling from a tree to Earth, converting its potential energy into kinetic energy or a particle orbiting the center, like a planet around a star, an orbit that decreases as the particle converts its potential energy into kinetic energy. Also, what comes before, cloud collapse or thermal radiation release, i.e. cloud collapse that causes thermal radiation to be released or thermal radiation release that causes the cloud collapse? If I want to do calculations, do I have to put all the mass of the cloud in the center?

Does the particle, when it emits thermal radiation, immediately lose kinetic energy to regain more as it converts its potential energy or does its kinetic energy only increase in the process, i.e. there is no momentary drop in kinetic energy.

I watched a video on the subject - a link that directs to the video in question is quoted at the bottom of the details - and it wasn't clear.

https://youtu.be/ULYK_9NwN28

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It doesn't make sense to think about the particles in a gas cloud being in orbit. The particles bump into each other and change their motion frequently. A gas cloud is supported by pressure, not orbital motion. However, if the cloud is systematically rotating that would be an additional source of (centrifugal) support.

In terms of what comes first, radiation or contraction - it is radiation that causes contraction. If the gas cloud has a temperature it will radiate, whatever its state of (dis)equilibrium.

If the gas cloud is spherically symmetric then you can assume that a particle is under the gravitational influence only of the mass interior to its radius, and that mass can be considered to be placed at the centre.

ProfRob
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