[Mesa-users] Blue loops

[Jeremy Sakstein]

Thanks Radek,

Comments below.

Cheers,

Jeremy

On Wed, Apr 3, 2019 at 11:21 AM Radek Smolec <smolec at camk.edu.pl> wrote:

> Dear Jeremy,
>
> śr., 3 kwi 2019 o 16:55 Jeremy Sakstein <sakstein at sas.upenn.edu>
> napisał(a):
>
>> Dear Mesa community,
>>
>> I've been using MESA to calculate blue loops for Z=0.0006 Cepheids in the
>> mass range [image: 5-13 M_\odot] and had a couple of questions I was
>> hoping you could answer.
>>
>> Nominally, I am a theorist so my approach so far has been to use the
>> inlist for 7M pre MS to AGB with
>>
> You may also start with 5M_cepheid_blue_loop in the test_suite.
>

Thanks. I didn't see this in the test suit (I am using 10398*)*


>
>
>>
>> mixing_length_alpha = 1.73
>> initial_z = 0.0006
>> alpha_semiconvection = 0.1
>> use_Ledoux_criterion = .true.
>>
>> and cary the initial mass over this range.
>>
>> Initially, I was only using 7-9 [image: M_\odot] but now I need to push
>> to a larger range and am getting funny results e.g. the loops cross.
>>
> What do you mean by "the loops cross"? That single evolutionary track
> passes through the same (Teff, L) point? For larger masses this is
> expected.
>

Yes, that is what I mean. Good to know this is normal.


>
>
>>
>> I am wondering if what I am doing is sensible given that the physics of
>> these objects could be very different depending on mass. In particular, I
>> am not sure what people typically use for e.g. the semi-convection
>> parameter at higher and lower masses.
>>
> I'm not sure what is the range of semi-convection parameter considered in
> the literature. 0.1 seems raesonable.
> Note that the shape and extent of the loops is very sensitive to many
> parameters: chemical composition, overshooting from the convective regions,
> rotation...
> Cheers,
> Radek
>
>
>> I'd be grateful for any help you can give.
>>
>> Cheers,
>>
>> Jeremy
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>
>>
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