[mesa-users] ionization fraction or kap table ?

[Jing Luan]

Hi Matthew,

Thank  you very much! If I want to call eval_ionization() in
run_star_extras.f, do I just need to add a line saying 'use ionization_lib'
near the beginning of that file please?

Thank  you :-)

Sincerely,
Jing

On Wed, Jun 28, 2017 at 4:32 AM, Matthew Clayton <
matthew.clayton at exeter.ox.ac.uk> wrote:

> Hi all,
>
> To add to Rich's answer, you can get MESA to output
> neutral_fraction_H
> neutral_fraction_He
> and
> avg_charge_He
> to profiles. Different linear combinations of these 3 values will give you
> all of the ionization fractions of H and He (exercise for reader).
>
> If you're looking to do calculations using ionization fractions within
> MESA itself, you can use the ionization module. Call eval_ionization() from
> ionization_lib and you can get lots of ionization data on a per-cell basis
> (I believe this is where the data in the profile output I mentioned above
> actually comes from). Word of warning though: that routine does
> occasionally give negative ionization fractions (or at least it did last
> time I used it), so I'm not sure how accurate it is in all cases.
>
> Hope that helps.
>
> Cheers,
>
> Matthew
>
> ------------------------------
> *From:* Jing Luan [jingluan.xw at gmail.com]
> *Sent:* 27 June 2017 16:01
> *To:* RICHARD H D TOWNSEND
> *Cc:* mesa-users at lists.sourceforge.net users
> *Subject:* Re: [mesa-users] ionization fraction or kap table ?
>
> Thank you very much, Rich. It is very useful :-) :-)
>
> Sincerely,
> Jing
>
> On Mon, Jun 26, 2017 at 9:27 PM, RICHARD H D TOWNSEND <
> townsend at astro.wisc.edu> wrote:
>
>> Hi Jing —
>>
>> > On Jun 24, 2017, at 9:55 AM, Jing Luan <jingluan.xw at gmail.com> wrote:
>> >
>> > Dear mesa users,
>> >
>> > 1, Are there parameters in mesa that tells the ionization fraction of
>> (HI to HII) and of (HeI to HeII) please? I search around
>> mesa/star/public/star_data.inc, but did not find any. But maybe I miss
>> something there.
>> >
>>
>> I would suspect not. Nowadays, with tabulated EOS’s, it is unusual to
>> actually solve the Saha equation during a stellar evolution calculation.
>> However, MESA *can* tell you the free electron number density, and so you
>> could calculate the ionization fractions yourself, using the Saha equation
>> (for this, I suggest you ignore excited states of the H/He).
>>
>> > 2, For calculating kappa mechanism due to H or He opacity bumps for
>> driving stellar oscillation, which kappa table and eos table should be
>> adopted please? The default in mesa-r8118 are
>> >
>> > kappa_file_prefix = 'gn93'
>> >
>> > eos_file_prefix = 'mesa'
>> > eosDT_Z1_suffix = '_CO_1'
>> > eosPT_Z1_suffix = ‘_
>> > CO_1'
>> >
>>
>> For the blue edges of the classical (Cepheid) instability strip, plotted
>> in Fig. 14 of Paxton et al (2015), I used:
>>
>> initial_zfracs = 6 ! Asplund et al. (2009)
>> kappa_file_prefix = 'a09' ! Asplund et al. (2009)
>>
>> …in the &star_job namelist, and
>>
>> initial_Y = 0.2703 ! Asplund et al. (2009) / proto-solar
>> initial_Z = 0.0142 ! Asplund et al. (2009) / proto-solar
>>
>> …in the &controls namelist. I expect the metallicity is less important to
>> driving classical Cepheid pulsations than the relative H/He abundances.
>>
>> cheers,
>>
>> Rich
>>
>> > Many thanks 😊😊😊😊
>> >
>> > Sincerely,
>> > Jing
>> > ------------------------------------------------------------
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>>
>
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