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I've been spelunking in this area recently and have been surprised to find there's still a lot unknown in star formation Most surprisingly, it seems there's a
by pmayrgundter 3y ago
I've been spelunking in this area recently and have been surprised to find there's still a lot unknown in star formation
Most surprisingly, it seems there's a formal paradox in the thermodynamics of self-gravitating systems. As Piet Hut (of Barnes-Hut fame) at the IAS says:
"A thermodynamic treatment of self-gravitating systems is fraught with peril: from a formal point of view, it cannot even be defined, because there is no thermodynamic limit." - Hut, Gravitational Thermodynamics [1]
Also surprising, thanks to JWST, we can now see clearly into the center of the Milky Way, and there's CO ice![2] Probably more types, but JSWT doesn't have the instrument for this.
This is related because that means it's colder than expected, but also quite full of gas (that was obscuring our view until JWST and near microwave). But cold dense gas should collapse to form stars, and we're not seeing nearly what we should.
Both suggest we're missing something about the grav/thermo relationship, and what's called the Jeans Mass[3]. If you go digging, you'll find our Sun should have taken a planetary nebula about 20x larger than what we have. This in turns suggests that simple static models are maybe misleading, as there's usually dynamics almost everywhere we see large gas clouds. And then this in turn begs the question of why gravitational collapse is needed if there's already large kinetic flows involved, slamming mass together.
Anyways, I'm a total amateur and quite possibly have all this wrong. Just dropping in case anyone's interested!
[1] https://www.ias.edu/ids/~piet/act/phys/thermo https://www.ias.edu/ids/~piet/act/phys/thermo
[2] https://www.youtube.com/watch?v=rKG9PIrQnnM https://www.youtube.com/watch?v=rKG9PIrQnnM
[3] https://en.wikipedia.org/wiki/Jeans_instability https://en.wikipedia.org/wiki/Jeans_instability
- dakr 3y agoJust a quick note to say that JWST is not the first telescope to give us these kinds of views! There are numerous others, SOFIA, IRAS, IRTF, and Alma to name a just a few.
- pmayrgundter 3y agoAh thanks! They mention Alma in the interview. Maybe the specific claim was that wavelength at a resolution good enough to resolve individual stars, or a star per pixel often enough
- contravariant 3y agoYeah it can be easy to forget but thermodynamics technically only aplies to whole systems at equilibrium. Which a star which constantly produces energy through fission is not. In most circumstances we get away with it, allowing us to assign temperatures to small objects or even locations in space but it's not surprising that these laws stop working at the extremes.
- selimthegrim 3y agoI feel like Lynden-Bell did a lot of work on this.
- pmayrgundter 3y agoThanks for the reference