2 ms·
Why doesn’t the stuff just falls in towards the center? It just floats there??
by brabel 9d ago
Why doesn’t the stuff just falls in towards the center? It just floats there??
- zygentoma 9d agoRadiation pressure! There is so much heat (= photons) radiating outwards, that it counteracts the gravitational pull.
- brabel 9d agoWow I knew that stars have that radiation pressure but had no idea it caused mass to get so crazy far away from the ignited area of the star!
- Sharlin 9d agoThese giant stars burn so very very bright. And correspondingly only live a few tens of millions years at most.
- stouset 9d agoWhat’s particularly interesting to me is that for stars the size of our sun, regular old gas pressure dominates. The sun’s atmosphere is held up essentially just from the temperature (and therefore high kinetic energy) of the plasma. Only once you get to 10+ solar masses does radiation (light) pressure begin to become significant, and at 50+ solar masses is when it dominates and the atmosphere is held up by the momentum of light.
- sega_sai 9d agoIn most star photospheres the role of radiation pressure is negligible. They are supported by the pressure gradients. The exception is very hot stars.
- kulahan 9d agoTo add on to the other response, think of it like the star “leaking” into space. It’ll be defined as a pretty radically different size at some point in the future, even as it’s still undergoing fusion.