[Mesa-users] Follow-up on binary evolution crash

[Mandal, Soham (uqa7ur)]

Hi all,

I am writing to follow up on my previous update on the issue I encountered with binary evolution with MESA. I was trying to evolve a binary system in MESA (M1=13M_sun, M2=10M_sun, P_i>=1300 days). The model crashed around 16-18 Myrs. Upon being advised by Jared, I investigated which derivative was failing, and for which star. Here's what I found:

It looks like the accretor star (with mass M2) fails first, with maximum residuals creeping up in the dlnE_dt equation. Surprisingly, when I treat the accretor as a point mass, the system still crashes, with the donor (with mass M1) failing a little later than the accretor would have, and residuals still creeping up in the dlnE_dt equation. I examined which derivatives were at fault for this simpler case, i.e., evolving the binary with the accretor as a point mass. I found that the log uncertainties for derivatives of dlnE_dt w.r.t. lnd, dlnE_dt w.r.t. lnT, dlnE_dt w.r.t. lnR were around -5, and that of dv_dt w.r.t. v were around -2. All of this happens around cell 49, which is quite close to the surface. Looks like a binary phenomenon to me.

I have attached the inlists, make and src directories, and the terminal outputs with this email for reference. I excluded the output where all the derivatives are examined in detail for avoiding confusion, but can be produced if needed. Can you please provide any suggestions or pointers on how to solve this issue? Any help will be greatly appreciated!

Thanks,
Soham
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