[Mesa-users] Failed to create a starting model

Fri Jul 1 15:17:22 UTC 2022

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> wrote:

> Sorry, I forgot to attach the new version of my inlist.
> ------------------------------
> *From:* Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of
> Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org>
> *Sent:* Friday, July 1, 2022 10:12 AM
> *To:* MESA Users List <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:
>
>
> 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:
>
>
> 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> on behalf of
> Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org>
> *Sent:* Thursday, June 30, 2022 3:18 PM
> *To:* Thomas Steindl <thomas.steindl at uibk.ac.at>
> *Cc:* MESA Users List <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> Sent: Thursday, June 30, 2022 1:58 PM To: Cao,
> Kaili <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>
> *Sent:* Thursday, June 30, 2022 1:58 PM
> *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
>
> 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
> Homepage: www.thomassteindl.com
> <https://urldefense.com/v3/__http://www.thomassteindl.com__;!!KGKeukY!xAtSuQ9Qz9hPLe4tG3P037LzaRiaandIbKs_hBTIz6XhMDP12DDa9BdxAigKXDAXvWBbyvHxBqmouJcOfivm3sXmRTS0KMAvjsI25qQy$>
>
> Am 30.06.2022 um 19:19 schrieb Cao, Kaili via Mesa-users <
> 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
> <inlist_start>_______________________________________________
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>
>
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>
>

-- 

Dr Meridith Joyce
Lasker Fellow
Space Telescope Science Institute
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