[Mesa-users] [Fe/H] Calculation with MESA Outputs

[Rob Farmer]

Please keep replies on the mesa-users list

Yes, using basic.net will be a problem as that net does not contain fe56. I
would suggest moving to at least one of the approx21 nets if you care about
fe56 but you should carefully consider what other isotopes and what physics
your problem needs.

To check what net you are using, look at the terminal output when the model
starts and it should state "net name XXX" where XXX is the net you are
using. There are also several star_job options (
https://docs.mesastar.org/en/r15140/reference/star_job.html#show-net-species-info)
to show what isotopes and reactions are included in your current net.

Rob

On Wed, 3 Nov 2021 at 09:39, Mitchell Dennis <mtde226 at hawaii.edu> wrote:

> Rob,
>
>
>
> Thanks for your reply. The fields I am using to calculate [Fe/H] are from
> the history columns output from column names “surface h1” and “surface
> fe56”. I have attached both my inlist and my run_star_extras.f file. I
> think the network I am using is basic.net.
>
>
>
> Thanks,
>
> Mitchell
>
>
>
> *From: *Rob Farmer <robert.j.farmer37 at gmail.com>
> *Sent: *Monday, November 1, 2021 11:19 AM
> *To: *Mitchell Dennis <mtde226 at hawaii.edu>
> *Cc: *mesa-users at lists.mesastar.org
> *Subject: *Re: [Mesa-users] [Fe/H] Calculation with MESA Outputs
>
>
>
> Please be specific in what fields you are using to calculate Fe/H, and
> what values each term mesa is providing you.
>
>
>
> Is this in a run_star_extras, or are you using history output or profile
> data?
>
>
>
> You think it's the nuclear network issue, so which network are you using
> (inlists & run_star_extras.f90 would be helpful here)?
>
>
>
> Thanks
>
> Rob
>
>
>
>
>
> On Mon, 1 Nov 2021 at 22:01, Mitchell Dennis <mtde226 at hawaii.edu> wrote:
>
> Dear MESA Mailing List,
>
>  I am writing to inquire about calculating the [Fe/H] metric using MESA
> outputs. Specifically, I am outputting the Iron mass fraction and the
> Hydrogen mass fraction at the surface of my model, but even when I give the
> inlist a metallicity Z > 0, my initial Fe abundance is zero (and remains at
> zero throughout the model). Because I am terminating my models at the tip
> of the red giant branch (TRGB), I do not expect the iron abundance to
> change substantially from core collapse to the TRGB, and MESA reflects this
> by not increasing the Iron mass fraction at all during my stellar model. I
> suspect this is due to the nuclear reaction network. Is this the case? How
> does MESA allocate initial metallicity between the various elements?
>
> Additionally, I was reading MESA paper on planets, oscillations, rotation,
> and massive stars which uses [Fe/H]s in Table as the log of the ratio of
> the surface (Z/X) relative to solar values. Is this drawing an equivalence
> between [Fe/H] and (Z/H), and would this be appropriate in my case at the
> TRGB? Bill Paxton *et al* 2013 *ApJS* *208* 4
>
> Additionally, does anyone have any suggestions for calculating [Fe/H]
> using MESA?
>
>
>
> Best Regards,
>
> Mitchell T Dennis
>
> Graduate Student
>
> Institute for Astronomy – UH Manoa
>
> _______________________________________________
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>
>
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