[Mesa-users] CCSN_IIp module: infall up to what radius?

[Jared Goldberg]

>
> Do we then expect the inner radius to gradually halt at some value? For
> example, in my model, R_center won't go below ~1600 km. How does one
> determine that infall has ended and now it's time to inject energy?

In *_to_core_collapse, Fe infall velocity.  In ccsn_IIp, a central radius
is specified (center_R_lower_limit = 4d+07). Is your R_center not going
below 1600 km in the ccsn_IIp setup?

Exploding a star in MESA is a feat of engineering as much as it is a feat
of physics, if not moreso.

Some people have calculated the evolution further in GR1D and STIR and PUSH
and some other frameworks, then ported back to MESA (see works by Sanjana
Curtis, Brandon Barker, others). It turns out that lightcurve modeling is
often *not* so sensitive to when you halt the infall and put in the bomb,
since you're using a thermal bomb that is the asymptotic energy + the
binding energy at that time, and not doing a "self-consistent" explosion
anyway (this is something many people have found through experimentation,
including myself, though I don't know of a great reference that shows it).
For the composition and explosive burning, it matters more, but then you
run into the problem that 1D explosion models don't get mixing at the
proto-neutron star boundary right, the explosion isn't actually 1D, et
cetera.

~Jared

On Thu, Jul 3, 2025 at 3:17 PM Mandal, Soham (uqa7ur) <soham at virginia.edu>
wrote:

> Thanks for that prompt clarification, Jared! So if I understand correctly,
> MESA choking at higher core densities sets an upper limit to the Fe core
> infall velocity stopping condition. In that case, one eventually has to
> calculate the rest of the core infall in the ccsn_IIp, after excising the
> proto-NS core.
>
> Do we then expect the inner radius to gradually halt at some value? For
> example, in my model, R_center won't go below ~1600 km. How does one
> determine that infall has ended and now it's time to inject energy?
>
> Thanks,
> Soham
> ------------------------------
> *From:* Jared Goldberg <jgoldberg at flatironinstitute.org>
> *Sent:* Thursday, July 3, 2025 2:38 PM
> *To:* Mandal, Soham (uqa7ur) <soham at virginia.edu>
> *Cc:* mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
> *Subject:* Re: [Mesa-users] CCSN_IIp module: infall up to what radius?
>
> The *_pre_ms_to_core_collapse models end with an Fe core infall velocity
> stopping condition -- to get to smaller radii, you can increase that
> velocity (see fe_core_infall_limit). However, MESA often chokes at higher
> and higher core densities, which is why the rest of the core infall is
> carried out *after *excising the proto-NS core in inlist_infall in the
> ccsn_IIp setup.
>
> ~Jared
>
> On Thu, Jul 3, 2025 at 2:22 PM Mandal, Soham (uqa7ur) via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
> Dear all,
>
> I am running into an issue while trying to use the CCSN_IIp test_suite
> problem. So the inlist_infall continues evolution of the star till the
> inner radius falls below 400 km. I'm not sure how to compute this value
> (400 km) for any arbitrary model.
>
> For example, in a pre-core-collapse model I ran, the inner radius won't go
> below ~1600 km (found by trial and error). Is there a way to compute the
> lower threshold of the inner radius and set the center_R_lower_limit parameter
> to that before the test problem is run? Any insight will be
> greatly appreciated!
>
> Thanks,
> Soham
>
>
>
> ------------------------------------------------
> Dr. Soham Mandal
> VITA postdoctoral research fellow
> Department of Astronomy
> University of Virginia
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
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