[Mesa-users] A very short timestep of the evolution of a He star appears during it towards an AGB star

[曾耀田]

Dear Dr. Jacqueline Goldstein and all MESA users,

Thanks for your help. 

As you suggested, the value of "varcontrol_target" is changed from 1d-4 to 1d-3 during the evolution of a He star (see log_val1d-3). Timesteps become larger at the same star age over the whole evolution. Timesteps still getting shorter when the He star close to the bottom of its AGB phase. However, the timestep becomes larger at the beginning of the He star at the bottom of its AGB phase and it increased for 7d4 years. Then it decreased by the limitation of the dHe/He. But, unfortunately, the evolution subsequently stops because of problems "dt < min_timestep_limit" with the information of "hydro_failed". I also try to change the value of "dHe_div_He_limit" from 0.9d0 to 2.0d1 (see log_val1d-3). This setting seems to lead to the timestep does not limit by dHe/He but the He star still can not evolve to the top of an AGB star so that toward a WD. I'm not sure whether or not the case I showed in the last email will face the same ending since it still can evolve after 100,000 steps with a timestep of 1d-8 yr. For this new problem, could you share some comments or suggestions? The attached files are log files for the two test settings mentioned in this email.

Looking forward to your reply!

Many Thanks!

Yaotian



-----Original Messages-----
From:"Jacqueline Goldstein" <jgoldstein at astro.wisc.edu>
Sent Time:2021-05-18 23:52:54 (Tuesday)
To: "曾耀田" <zengyaotian at ynao.ac.cn>
Cc: "mesa-users at lists.mesastar.org" <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] A very short timestep of the evolution of a He star appears during it towards an AGB star

Hi Yaotian,


I see that your varcontrol_target is 1d-4. Based on recent experience, I suggest changing it to 1d-3.


I am more familiar with evolving massive main-sequence stars than I am in evolving post-main sequence stars, but I recently had an experience with very short time steps in response to evolving a model including mass-loss, and increasing the varcontrol_target from 1d-4 to 1d-3 resulted in my time steps changing from 1d-4 to 1d+4.


If you try this suggestion, let us know how it goes.


Sincerely,


Jacqueline Goldstein, Ph.D. (she/her/hers)
Astronomy | Life Sciences Communication 
University of Wisconsin — Madison
http://www.astro.wisc.edu/~jgoldstein




On May 17, 2021, at 2:02 AM, 曾耀田 <zengyaotian at ynao.ac.cn> wrote:


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