In order to grow, a nucleated (condensed), cold star core must accumulate hydrogen as future mass and fuel before igniting to fusion and becoming a full fledged shining star. But there is a problem in the way. Just as the sun cannot accumulate planets via gravity, without some mechanism to shed angular momentum, hydrogen will just orbit the baby star and not accumulate upon it. Viscous drag both dissipates angular momentum and allows hydrogen molecules to accumulate by spiraling down to the star. Unlike a planetary orbit, in a spiral gravity, angular momentum, and viscous drag (friction) are not orthogonal to one another, allowing friction to dissipate momentum as the gravitational fall increases it. Upon arrival at the star, there remains a lot of angular momentum that still need dissipating. Compressed, hot hydrogen forms a metallic core on the star where it creates an electromagnetic magneto – a sort of electric motor. The magneto converts angular momentum into linear momentum that squirts out as jets from the poles. Both mechanisms allow hydrogen to accumulate without spinning the young protostar to death. The jets also advertise to us that star formation is going on and results in beautiful images.
Fueling up a New Star – Gravity vs Angular Momentum
