[Mesa-users] Magnetic field calculations

[Croxmor Moraga]

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/20200523/9e442b05/attachment.htm>