[mesa-users] Evolution Problems

[Bill Paxton]

On Jul 20, 2013, at 5:39 PM, Steven wrote:

> Hello all,
> 
> I have been trying to run a 40M model were I remove the surface until the mass is around 15.7M during the core Helium burning phase.
> 
> When I run the model without mass loss, it will evolve all the way to an Iron core. However, when I attempt to remove the mass it gets stuck in the core Carbon burning phase.

Hi Steven,

Your timing with this was good -- I've been working intensely on massive stars, so I decided to run yours as a test.
After several trials to tweak the mass loss, I ended up pretty close: I got a final mass of 15.45M.  A small decrease in the
wind should get your 15.7M.  I used "Dutch" wind with eta = 0.5 plus some rotation (initial omega/omega_crit = 0.1).
I used initial Z = 0.02 and ran from zams to core collapse with "hands off".

As you might expect (or hope?), it ends up very bright and very blue.  logL = 5.78 and Teff about 2e5.
During the rapid mass loss (He burning) it wonders around in the HR diagram, but at the end it moves left and then up.
It spends about 10^5 years bright and blue before core collapse.  The mass loss happens before it gets bright and blue.
There's NO hydrogen left.  The surface is 98% He and 2% metals (modulo effects of diffusion which wasn't included).
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At core collapse, there is an oxygen core out to about 12M, silicon out to about 2.9M and "iron"  out to about 2.1M.
center Ye is about 0.436
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The run used 1673 steps with 56 retries and 35 backups.   I didn't get an exact timing, but it was pretty quick on my 12 core mac (about 15 minutes I believe).

I hope this inspires you to do great things with MESA!  ;p

cheers,
Bill

version: 5247
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