[Mesa-users] Blue loops

[Radek Smolec]

> One final question: I can’t  seem to get blue loops that cross the
> instability strip for say 13M models.
>
Above some mass loops disappear in most evolutionary calculations I'm aware
off. Above 10Ms loops may be difficult to get, independent what parameters
you are using.
Check when core helium burning starts in your model. For massive models
central helium burning starts already on the way to RGB and loops do not
develop.
Cheers,
Radek


>
> Do I need to change the controls in the inlist due to other physical
> processes kicking in?
>
> Cheers,
>
> Jeremy
>
> On Wed, Apr 3, 2019 at 12:54 PM Jeremy Sakstein <sakstein at sas.upenn.edu>
> wrote:
>
>> Thanks Radek,
>>
>> It looks very similar to the inlist I am using so that is good. The only
>> difference is the mixing length scheme. I think for my purposes as long as
>> I am consistent this should not matter too much.
>>
>> Cheers,
>>
>> Jeremy
>>
>> On Wed, Apr 3, 2019 at 11:34 AM Radek Smolec <smolec at camk.edu.pl> wrote:
>>
>>> Jeremy,
>>> for 5M_cepheid_blue_loop see the recent public release.
>>> I attach the relevant inlist for your reference.
>>>
>>> You may also take a look at Section 2.4.2 of the instrument paper:
>>> https://arxiv.org/abs/1903.01426
>>> Tracks in Figure 13 were computed using this test_suite example.
>>> Cheers,
>>> Radek
>>>
>>>
>>> śr., 3 kwi 2019 o 17:25 Jeremy Sakstein <sakstein at sas.upenn.edu>
>>> napisał(a):
>>>
>>>> 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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