[Mesa-users] blue loops with mesa

[David Arnett]

Hi Jakub and Bill,
I am not surprised at Jakub's experience. In retrospect it seems inevitable
with a chaotic system. We need more constraints from physics.
We have made significant progress with 3D simulations (my group and Paul
Woodward's) in defining physically motivated overshooting and boundary
physics.
The theory is clear. The implementation in MESA is still a problem.
I think that if this approach "fails" it is due to a flaw in a different
aspect of the code physics, not a parameter choice (which is a good thing)!
Dave

On Sun, Jul 1, 2018 at 12:44 PM, ostrowski <ostrowski at astro.uni.wroc.pl>
wrote:

> Hi Bill,
>
> Blue loops are hopeless ;)
>
> Actually, it's very easy to obtain and believable blue loops in mesa. You
> need a proper initial mass, at least 3 Ms, but 4 Ms would be more reliable,
> and not higher than, let's say, ~10 Ms. Then apply some inward overshooting
> from the outer convective envelope and you're done. So what's the catch you
> ask? Well, you can't predict what else you need. Additional mixing like
> core overshooting during main-sequence evolution or rotational mixing
> during MS can strongly affect emerging of the loops. In order to find some
> rules at some point of time I analysed large grids of models with a lot of
> variables but I gave up eventually. There are no hard rules - that's my
> best conclusion and I don't feel it's suitable for publication.
>
> Cheers,
> Jakub
>
>
> On 2018-07-01 20:31, Bill Paxton wrote:
>
>> i’ve been “out of the loop” on the topic of blue loops.
>>
>> i recall that Jakub Ostrowski did work on this, but i can’t find
>> anything in ADS.
>>
>> is there a reliable recipe for getting believable blue loops in mesa?
>>
>> thanks
>> Bill
>>
>>
>>
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>


-- 
David Arnett
Regents Professor
Steward Observatory
University of Arizona

Facts are stubborn, but statistics are more pliable.  Mark Twain
Facts do not cease to exist because they are ignored.  Aldous Huxley
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