I was recently watching a video on the physics and chemistry in planetary accretion disks, and the speaker at a certain point mentioned 'freeze-out and UV dissociation'. Is freeze-out a purely chemical term, or is it specific for this process? Is it very important in planetary formation?


1 Answer 1


Freeze-out is indeed a chemical term. It happens in the midplane of accretion disks where density is high enough to block UV ionization/chemical dissociation and limit heating from the central star. No one seems to have gotten around to writing up a layman friendly article on the subject yet, but these refs give the gist:

Protostars and planets V

Accretion Disks 1: During Star Formation

Organic Matter in Space (IAU S251) Evolution of Organic Matter

From ref 2:

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  • $\begingroup$ Aah, so ist pretty much the same thing as the dead zone? I am not sure if they are related, but I actually am using the Protostars and planets IV conference on YouTube for my research, so maybe there are different speakers that are just using different terminology for the same phenomena. Thank you, I will certainly read your links! $\endgroup$
    – L.R.
    Jan 5, 2015 at 19:13

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