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It's the point where light pressure can blow off the outer layers of a star

https://en.wikipedia.org/wiki/Eddington_luminosity

Objects that pulse like

https://en.wikipedia.org/wiki/Eta_Carinae

can evade it and there are other ways too.

When it comes to super-massive black holes there is the question of how quickly stuff can even get close enough to the black hole to get into the accretion disk.

500M years is a long time for the kind of large star that becomes a black hole (blows up in 10M years or so), but if one black hole is going to merge with another black hole and that is going to merge with another black hole and so on there is no Eddington limit (no EM radiation!) but rather the even slower process of shedding angular momentum via gravitational radiation. (One highlight of grad school was the colloquium talk where we got to hear the signal from two black holes colliding almost 20 years before it was detected for real)

I hope JWST sees

https://en.wikipedia.org/wiki/Stellar_population#Population_...

Note those Pop 3 stars have a higher Eddington limit because they've got hardly any "metal" in them which means light interacts with them differently, although astronomers have the strange (to me) conventional that anything heavier than Helium is a metal which includes, say, oxygen. (As a cond-mat PhD I think a metal is something that has free electrons, which could be one of those elements towards the left side of the periodic table or could be a doped semiconductor or polymer like polyaniline)



Thank you. I did not know that the first cosmic generation of stars had a higher Eddington limit. Why does light interact differently with hydrogen and helium than it does with the other elements? Does it have anything to do with having only a single layer of electrons in the atom?




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