[Mesa-users] Problems converging low mass stars because of min_timestep_limit

[Francis Timmes]

hi inma,

super!

fxt



> On Mar 19, 2024, at 2:10 AM, Inma Moyano <inmamoyano12 at gmail.com> wrote:
> 
> Hi Francis,
> 
> Thank you, it worked for every opacity and net combination. I'll also check the inlists that you recommended.
> 
> Best regards,
> Inma
> 
> El vie, 15 mar 2024 a las 17:26, Francis Timmes (<fxt44 at mac.com <mailto:fxt44 at mac.com>>) escribió:
>> hi inma,
>> 
>> i ran your inlist in r24.03.1. while i didn't investigate every opacity/net experiment, i found that increasing the mass resolution from ~300 cells in your original inlist to ~1700 cells via
>> 
>> ! mesh controls
>>       mesh_delta_coeff = 1
>>       max_dq  = 1d-3
>> 
>> allows the model to run smoothly to completion:
>> 
>> stop because star_age >= max_age
>>     0.2000000000E+10    0.2000000000E+10
>> 
>> you could also explore the inlists from farag et al 2024 at
>> 
>> https://doi.org/10.5281/zenodo.8327401
>> 
>> especially example_1Msun_solar_Z for setups and settings.
>> 
>> fxt
>> 
>> 
>> 
>> 
>> > On Mar 12, 2024, at 5:43 AM, Inma Moyano via Mesa-users <mesa-users at lists.mesastar.org <mailto:mesa-users at lists.mesastar.org>> wrote:
>> > 
>> > Dear MESA Users,
>> > 
>> > My name is Inma, a master's student. I am using MESA's version 23.05.1 on Ubuntu 23.10.
>> > 
>> > I am working on models for low mass stars (0.1, 0.35 and 0.6 Msun), testing different sets of opacity tables for low temperatures (kap_lowT_prefix = 'lowT_fa05_a09' , 'lowT_Freedman11') and also experimenting with the nuclear reaction networks (options 'basic.net <http://basic.net/>', 'h_burn.net <http://h_burn.net/>' and 'mesa_49.net <http://mesa_49.net/>'). 
>> > 
>> > I had no issues using the net 'basic.net <http://basic.net/>', but when I use 'h_burn.net <http://h_burn.net/>' and 'mesa_49.net <http://mesa_49.net/>' some models of 0.35 and 0.6 Msun do not converge due to the following error:
>> > 
>> >                                                      dt    6.9699513407705602D-09
>> >                                      min_timestep_limit    1.0000000000000000D-08
>> >  stopping because of problems dt < min_timestep_limit
>> > terminated evolution: cannot find acceptable model
>> > termination code: min_timestep_limit
>> > 
>> > None of my 0.35Msun models converge using any of the two nets or opacities. WIth regard to 0.6Msun models, they only converge using 'lowT_fa05_a09' opacity, for both nets, but when I change the opacity to Freedman11 they don't anymore. 
>> > Has anyone had this problem before or knows why this is happening? Here I attach my inlist_project file and also the net files.
>> > 
>> > Best regards,
>> > Inma
>> > 
>> > 
>> > 
>> > <h_burn.net <http://h_burn.net/>><inlist_lowmass_nets><mesa_49.net <http://mesa_49.net/>>_______________________________________________
>> > mesa-users at lists.mesastar.org <mailto:mesa-users at lists.mesastar.org>
>> > https://lists.mesastar.org/mailman/listinfo/mesa-users
>> > 
>> 

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