[Mesa-users] Failed to create a starting model

Cao, Kaili cao.1191 at buckeyemail.osu.edu
Fri Jul 1 17:42:14 UTC 2022 

Hi Meridith,

Thanks a lot for sharing your valuable experience. I am studying whether setting
pre_ms_check_radiative_core_Lnuc_div_L_limit = 1d-6
works, and will test the numerical precisions and different atmosphere choices.

Cheers,
Kaili
________________________________
From: Meridith Joyce <meridith.joyce at gmail.com>
Sent: Friday, July 1, 2022 11:17 AM
To: Cao, Kaili <cao.1191 at buckeyemail.osu.edu>
Cc: MESA Users List <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] Failed to create a starting model

Hi Kaili, I spent a few months last year looking at a similar problem. There are, in my opinion, some still-unresolved issues when it comes to the pre-main sequence relaxation procedure (in particular, that it causes "proper" evolution

Hi Kaili,

I spent a few months last year looking at a similar problem. There are, in my opinion, some still-unresolved issues when it comes to the pre-main sequence relaxation procedure (in particular, that it causes "proper" evolution for a low-mass model to begin at too hot a temperature).

The following settings have helped me with low-mass stellar models using deuterium burning:

&star_job
    pre_ms_T_c = 3d5 ! default -- any lower doesn't work
    pre_ms_check_radiative_core_min_mass = 0.3d0 ! default is 0.3d0
    pre_ms_check_radiative_core_Lnuc_div_L_limit = 1d-6

&controls

    atm_option = 'table'
    atm_table = 'photosphere'

In the inlist I'm pulling from, I also use weaker mesh and time restrictions than you do:
    mesh_delta_coeff = 0.8
    time_delta_coeff = 1.0

Let me know if that works.

Cheers,

On Fri, Jul 1, 2022 at 10:17 AM Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>> wrote:
Sorry, I forgot to attach the new version of my inlist.
________________________________
From: Mesa-users <mesa-users-bounces at lists.mesastar.org<mailto:mesa-users-bounces at lists.mesastar.org>> on behalf of Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Sent: Friday, July 1, 2022 10:12 AM
To: MESA Users List <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Subject: [Mesa-users] Failed to create a starting model

Dear MESA Users, Following Thomas’s advice, I set pre_ms_relax_to_start_radiative_core = .false. to build my starting model with specified initial deuterium abundance. Although this enabled MESA to produce some results, the issue has not been
Dear MESA Users,

Following Thomas’s advice, I set pre_ms_relax_to_start_radiative_core = .false. to build my starting model with specified initial deuterium abundance. Although this enabled MESA to produce some results, the issue has not been resolved, and a more severe problem has occurred when I tried to use higher numerical precision.

Using the attached inlist (updated in this email), I repeatedly got:
retry: max residual jumped -- give up in solver
retry: avg+max resid -- give up in solver
retry: max resid -- give up in solver
Quantitatively, I got the “give up in solver” message 206 times for 1137 models. Although the resulting H-R diagram (see below; the blue curve corresponds to this inlist) seems reasonable, such a large fraction of “give up in solver” models make the results suspicious.

H-R diagram with mesh_delta_coeff = 1.0d0:
[cid:181ba51c61c9eb1274d1]

Besides, it took 21.0 minutes for the starting model to reach central deuterium exhaustion; in contrast, the entire evolution from the central deuterium exhaustion to the RGB bump (the orange curve in the above plot) took only 23.4 minutes. Such a high time consumption was not expected for a starting model.

The time consumption becomes unacceptable when I reran the same simulation with a higher spatial resolution (mesh_delta_coeff = 0.5d0). Usually when I halve mesh_delta_coeff, I double the time consumption. However, this time it took MESA 16.5 hours to simulate a small fraction of the previous case. See the H-R diagram below.

H-R diagram with mesh_delta_coeff = 0.5d0:
[cid:181ba51c61c9eb1274d2]

Could you please provide me with some hints about the large fraction “give up in solver” models and the high time consumption of my starting models? Thank you for your time and I look forward to your response.

Best regards,
Kaili Cao

________________________________
From: Mesa-users <mesa-users-bounces at lists.mesastar.org<mailto:mesa-users-bounces at lists.mesastar.org>> on behalf of Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Sent: Thursday, June 30, 2022 3:18 PM
To: Thomas Steindl <thomas.steindl at uibk.ac.at<mailto:thomas.steindl at uibk.ac.at>>
Cc: MESA Users List <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Subject: Re: [Mesa-users] Failed to create a starting model

Hello Thomas, Thank you for your quick and insightful reply. I really appreciate it. Cheers, Kaili From: Thomas Steindl <thomas.steindl at uibk.ac.at<mailto:thomas.steindl at uibk.ac.at>> Sent: Thursday, June 30, 2022 1:58 PM To: Cao, Kaili <cao.1191 at buckeyemail.osu.edu<mailto:cao.1191 at buckeyemail.osu.edu>>
Hello Thomas,

Thank you for your quick and insightful reply. I really appreciate it.

Cheers,
Kaili
________________________________
From: Thomas Steindl <thomas.steindl at uibk.ac.at<mailto:thomas.steindl at uibk.ac.at>>
Sent: Thursday, June 30, 2022 1:58 PM
To: Cao, Kaili <cao.1191 at buckeyemail.osu.edu<mailto:cao.1191 at buckeyemail.osu.edu>>
Cc: MESA Users List <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Subject: Re: [Mesa-users] Failed to create a starting model

Hello Kaili, I was able to run your inlist to completion by setting pre_ms_relax_to_start_radiative_core = .false. This will start the evolution at the Hayashi track instead of first evolving the initial model until a radiative core develops.
Hello Kaili,

I was able to run your inlist to completion by setting

pre_ms_relax_to_start_radiative_core = .false.

This will start the evolution at the Hayashi track instead of first evolving the initial model until a radiative core develops. I am speculating here, but the issues could be related to putting deuterium into the stellar core with central temperature that  far exceeds the temperature at which deuterium burning starts.

>From your inlist it seems like you are interested in finishing the evolution during the phase of deuterium burning. For this you will have to start before the creation of the radiative core anyway.

Best,
Thomas
__________________________________________________________________

Thomas Steindl, MSc
University of Innsbruck | Institute for Astro- and Particle Physics
Tel: +43 512507 52031
Mail: thomas.steindl at uibk.ac.at<mailto:thomas.steindl at uibk.ac.at>
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Am 30.06.2022 um 19:19 schrieb Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>:

Dear MESA Users,

Thank you for reading this email.

I am trying to create a starting model using the attached inlist. The only difference between this version and a previous version that worked is the way I set the initial composition. However I got:
stopping because of problems dt < min_timestep_limit
terminated evolution: cannot find acceptable model
termination code: min_timestep_limit
Could you please point out the problem(s) with my inlist? Thanks.

Besides, I tried to solve this problem by using a simpler atmosphere. However, by examining the source code atm_support.f90, it seems to me that none of the fixed_something choices presented in the documentation is still available. Is there any available atmosphere simpler than the default Eddington grey atmosphere, which is easier for MESA to yield a starting model?

Thank you for your time and I look forward to your response.

Best regards,
Kaili Cao
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--

Dr Meridith Joyce
Lasker Fellow
Space Telescope Science Institute
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