[Mesa-users] STELLA calculation fail to converge for massive stars

[amar at aries.res.in]

Dear MESA team, 

MESA Version : 11701 
OS : ubuntu 20.04 

I am trying to study the evolution of very massive stars (in particular 400M_sun without any rotation and mass loss) with the help of MESA. I could evolve the star up to the stage of core-collapse. Here, I wish to discuss and understand few points : 

a) I could notice that after finishing the inlist_to_si_burn stage in the example_make_pre_ccsn directory, the model fails to achieve the prescribed temperature (lgT) of 9.85 while running inlist_to_lgT9.9 , so I decreased the limit to 9.61 and rerun the calculation. This time the evolution successfully proceeded. Please note that even a lgT of 9.62 was not achieved so I tried 9.61. 

b) Thereafter, the shock is evolved using the example_ccsn_IIp directory with few changes like, in inlist_infall , we required to change the remove_initial_center_by_entropy = 19.6 (default value is 4). Few timestep adjustments were also done. Then the calculation proceeded nicely and the mesa.abn and mesa.hyd (please see attached ) files were successfully created. Please take a look to inlist_shock_part5 also. 

c) These two files were then used as input for STELLA calculations. The STELLA calculation started nicely but seems that it fails to converge. On a 16GB RAM and octa-core processor machine, the calculations ran up to a period of more than 24hours but the light curve only up to 7days was produced with the calculation still going on. 

Please suggest me some possible methods to get convergence of STELLA calculation. Also, suggest if I am doing something wrong. 

With thanks and best regards, 
Amar 

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