[Mesa-users] Magnetic field calculations

[Rob Farmer]

>what I was referring to was about more advanced calculations of the
magnetic field, using MHD like for example Alfven waves, etc; it could have
other variations on the form of the field itself plus to the classical
dynamo form?

No mesa doesn't include more complicated magnetic field interactions.

>It is possible to conditionate my run_star_extras to use one mass-loss
equation created by me in one phase of the model, and after that in the
same run_star_ extras make it to use another one?

Yes, the other_wind routine (star/other/) computes the mass loss at each
timestep and thus you can vary the mass loss depending on the stellar
properties at each timestep.

Rob



On Sun, 24 May 2020 at 04:07, Croxmor Moraga <
rodrigo.moraga.merino at gmail.com> wrote:

> Thank you so much! It worked.
> That's useful; what I was referring to was about more advanced
> calculations of the magnetic field, using MHD like for example Alfven
> waves, etc; it could have other variations on the form of the field itself
> plus to the classical dynamo form?
> By the way, a more complex question, from what I want to include in my
> mesa code, as I mentioned in previous emails, are the effects of magnetic
> field evolution in the mass-loss process, by following the examples of
> Cranmer & Saar 2011, and more specifically Mullan & Macdonald 2019, by
> including the effects of eddies in the interior region of the photosphere
> that appears after the RGB bump, but for that, I want to know:
> It is possible to conditionate my run_star_extras to use one mass-loss
> equation created by me in one phase of the model, and after that in the
> same run_star_ extras make it to use another one?
> And if it is not possible, is there another way to do that?
> From beforehand thank you.
>
> El lun., 11 de mayo de 2020 08:14, Rob Farmer <r.j.farmer at uva.nl>
> escribió:
>
>> Hi,
>> It's a little unclear what you mean by magnetic fields (in this context)
>> as there are many ways you could include them, depending on what you want
>> to investigate.
>>
>> MESA can include a Spruit-Tayler dynamo (there's even a pgstar plot
>> "dynamo" to view the output) and can be used to mix angular momentum and
>> chemical composition between zones by way of a diffusion equation.
>>
>> If you look in star/private/rotation_mix_infio.f90 and search for
>> dynamo_B_r you'll find:
>>
>>                      ! calculate B_r and B_phi
>>                      do k = 1, nz
>>                         q = s% omega_shear(k)
>>                         s% dynamo_B_r(k) = & ! eqn 11, Heger et al. 2005
>>                            pow(pow2(4D0*pi*rho(k)*s%
>> nu_ST(k)*q/r(k))*abs(omega(k))*s% nu_ST(k),0.25D0)
>>                         s% dynamo_B_phi(k) = & ! eqn 12, Heger et al. 2005
>>
>>  pow(pow2(4D0*pi*rho(k)*omega(k)*q*r(k))*abs(omega(k))*s% nu_ST(k),0.25d0)
>>                      end do
>>
>> Which is computing a B field in the radial and phi directions based on a
>> Spruit-Tayler dynamo. I would suggest reading up on the Heger et al 2005
>> paper if you want more details on this.
>>
>> Rob
>>
>>
>> On Sun, 10 May 2020 at 01:14, Croxmor Moraga via Mesa-users <
>> mesa-users at lists.mesastar.org> wrote:
>>
>>> Greetings mesa community, I hope everyone is okay right now.
>>> I want to ask about magnetic field calculations with the MESA
>>> calculations. I searched for it between the mesa functions, but I couldn't
>>> find any about it.
>>> Does the program has it but I haven't found it? Or if it is not included
>>> in those functions, has anyone here added those calculations in a
>>> run_star_extras file within their own work?
>>> And if you did, which variables did you used in order to?
>>> From beforehand, thank you to all of you and have a nice day/night.
>>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200526/048074b6/attachment.htm>