"Jittering jets in stripped-envelope core-collapse supernovae", Wang, Shishkin, Soker 2025

Models, inlists and modified files as described in "Jittering jets in stripped-envelope core-collapse supernovae" by Wang, Shishkin, Soker 2025.

Using the one-dimensional stellar evolution code MESA, we find that all our models in the initial mass range of M_ZAMS=12-40Mo, regardless of whether they have hydrogen-rich, hydrogen-stripped, or helium+hydrogen-stripped envelopes, have at least one significant strong convective zone in the inner core, which can facilitate the jittering-jets explosion mechanism (JJEM). 
We focus on stripped-envelope CCSN progenitors that earlier studies of the JJEM did not study, and examine the angular momentum parameter j(m)=rv_conv, where r is the radius of the layer and v_conv is the convective velocity according to the mixing length theory. In all models, there is at least one prominent convective zone with j(m) > 2x10^15 cm^2/s inside the mass coordinate that is the maximum baryonic mass of a neutron star (NS), m~2.65Mo. According to the JJEM, convection in these zones seeds instabilities above the newly born NS, leading to the formation of intermittent accretion disks that launch pairs of jittering jets, which in turn explode the star. Our finding is encouraging for the JJEM, although it does not show that the intermittent accretion disks indeed form. We strengthen the claim that, according to the JJEM, there are no failed CCSNe and that all massive stars explode. In demonstrating the robust convection in the inner core of stripped-envelope CCSN progenitors, we add to the establishment of the JJEM as the primary explosion mechanism of CCSNe. 

We use the one-dimensional stellar evolution code MESA (Modules for Experiments in Stellar Astrophysics; version 24.08.1, SDK version x86_64-linux-24.7.1) to simulate twelve different masses of core-collapse supernovae progenitors, having zero-age main sequence masses ranging M_ZAMS=12-40Mo. For each mass we simulated three scenarios of envelope stripping: a regular wind that leaves a hydrogen-rich envelope at the explosion (``full envelope''), evolution that includes an extra mass loss that removes the hydrogen but leaves helium (``H-stripped envelope''), and the removal of both hydrogen and helium (``He-stripped envelope'').

Models

We make available our set of models at the onset of collapse, where the infall velocity at atleast one mass coordinate exceeds 100 km/s. These are organized according to initial mass, envelope removal, and the (arbitrary) profile number assigned at simulation time as part of the final segment leading to core collapse: ##M_{}profileZZZ.data; ## is the initial stellar mass, {} corresponds to envelope removal ('' for non, '_H' for hydrogen envelope removal and '_He' for helium envelope removal) and ZZZ the profile number along the simulation.

Modified files

We implement a helium envelope removal scheme that is identical in spirit to the hydrogen removal scheme within MESA. For consistency, we chose to precisely duplicate the hydrogen removal scheme, but set the removal to be to the carbon-oxygen core (from helium core in the default hydrogen removal scheme).
As the MESA removal scheme is a star_job routine, we modified source files in the following locations and added a new removal routine and appropriate references:

• star/public/star_lib
• star/private/star_job_ctrls_io
• star/defaults/star_job.defaults
• star/run_star_support.f90
• include/star_job_controls.inc , star_data/private/star_job_controls.inc

Exact lines modified can be found by searching for the new routines names: relax_mass_to_remove_He_env, relax_initial_mass_to_remove_He_env

Inlists

We add an example set of inlists used to run the simulation. These are based on the `20M_pre_ms_to_core_collapse' test_suite example.