[Mesa-users] Nonphysical behavior of outermost envelope of rapidly rotating stars

[Tomasz Plewa]

Great - thanks, Aldo.

I said I suspect a model failure, meaning the solution entering a regime it was not designed for, because neither resolving my models better numerically nor changing available physics options stabilized solutions.

If I recall correctly, my impression was that failing models were evolving toward rotational ejection of the envelope, or some parts of it,  but the algorithm was not capable of handling such situations.

Tomek
--
> On Jul 29, 2020, at 4:18 AM, Aldo Serenelli <aldos at ice.csic.es> wrote:
> 
>  Hi Tomek, Larry, 
> 
> I've passed the question to M. Asplund about density inversions in his 3D hydro, and they also happen in his full RHD 3D models, related to ionization of H and change in molecular weight. This coincides with regions of quick (spatially) opacity variations, in the region where convective velocities are largest (which is probably around the temperatures in which Larry finds it). Martin finds other situations in which they also occur (hotter dwarfs, in the direction of that old 1970 reference).
> 
> Best, 
> 
> Aldo
> 
> 
> 
> 
> 
> 
> On 29/07/2020 01:11, Tomasz Plewa via Mesa-users wrote:
>> Thank you, Larry. I suspected the observed runaways to be related to the abnormal structure of the outer layers. This is good news.
>> 
>> The bad news is I was never successful with resolving this problem by tweaking great many readily accessible runtime parameters. Although Aldo might onto something re convection, my experience makes me believe the model (physical, numerical) needs modified.
>> 
>> My cases were limited to massive, fast rotating, mass losing RSGs. I will be eager to return to those studies, of course!
>> 
>> Tomek
>> --
>> 
>>> On Jul 28, 2020, at 4:23 PM, Larry Molnar <lmolnar at calvin.edu> wrote:
>>> 
>>> 
>>> Here are the plots a second time scaled to zoom in on the outer layers only.
>>>  
>>>  
>>> From: Larry Molnar <lmolnar at calvin.edu> 
>>> Sent: Tuesday, July 28, 2020 4:17 PM
>>> To: Tomasz Plewa <tplewa at fsu.edu>
>>> Cc: Pablo Marchant <pamarca at gmail.com>; mesa-users at lists.mesastar.org
>>> Subject: RE: [Mesa-users] Nonphysical behavior of outermost envelope of rapidly rotating stars
>>>  
>>> Here are some sample log(rho)-log(T) plots for the case of M = 1.0 Msun, Omega/Omega_crit (initial) = 0.42. The excursion to low surface temperature/large radius occurred in profiles 146-225. My samples include before, during and after the excursion.
>>>  
>>> I see that the density briefly *increases* with increasing radius in the outermost layers of the suspect profiles.
>>>  
>>> From: Tomasz Plewa <tplewa at fsu.edu> 
>>> Sent: Monday, July 27, 2020 4:58 PM
>>> To: Larry Molnar <lmolnar at calvin.edu>
>>> Cc: Pablo Marchant <pamarca at gmail.com>; mesa-users at lists.mesastar.org
>>> Subject: Re: [Mesa-users] Nonphysical behavior of outermost envelope of rapidly rotating stars
>>>  
>>> Larry -
>>> 
>>> Can you show the log(rho)-log(T) plot, please? How the density looks like in the surface layers?
>>> 
>>> Tomek
>>> 
>>> <190LogRhoLogT.png>
>>> <220LogRhoLogT.png>
>>> <250LogRhoLogT.png>
>>> <130LogRhoLogT.png>
>>> <160LogRhoLogT.png>
>> 
>> 
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>> 
> 
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