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

[Jared Goldberg]

Actually, I did think of a good reference for piston vs thermal bomb: The
SNEC instrument paper!
https://ui.adsabs.harvard.edu/abs/2015ApJ...814...63M/abstract

~Jared

On Thu, Jul 3, 2025 at 3:41 PM Jared Goldberg <
jgoldberg at flatironinstitute.org> wrote:

> 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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