Open-Astrophysics-Bookshelf / star_formation_notes

A set of notes on star formation
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Toomre vs. Jeans masses for disks #5

Closed low-sky closed 7 years ago

low-sky commented 7 years ago

Hi @markkrumholz

In Chapter 9, Equation 9.2, you refer to the mass of the GMC as the Toomre mass in this line, but that looks like the Jeans mass for a thin disk (to within a factor of π/4). Is this a typo or a case of me not understanding what you're getting at here?

markkrumholz commented 7 years ago

On 6 Feb 2017, at 2:57 PM, Erik Rosolowsky notifications@github.com wrote:

Hi @markkrumholz https://github.com/markkrumholz In Chapter 9, Equation 9.2, you refer to the mass of the GMC as the Toomre mass in this line https://github.com/Open-Astrophysics-Bookshelf/star_formation_notes/blob/master/chapters/chapter9.tex#L117, but that looks like the Jeans mass for a thin disk (to within a factor of π/4). Is this a typo or a case of me not understanding what you're getting at here?

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/Open-Astrophysics-Bookshelf/star_formation_notes/issues/5, or mute the thread https://github.com/notifications/unsubscribe-auth/ALnL0lwyRRt03-wcrhSnV5VS9gH2i1noks5rZporgaJpZM4L3wUq.

You’re right, it is the 2D Jeans mass, though that is in fact the same as the Toomre mass up to factors of order unity for Q ~ 1. However, this definitely should be fixed in the text. Thanks for catching it. Do you want to push a change, or would you like me to?

I will also look at the typo fixes you PR'ed earlier today some time in the next day or so.

-- Mark Krumholz http://www.mso.anu.edu.au/~krumholz/

low-sky commented 7 years ago

:+1: Added to the PR.