[Mesa-users] metallicity in binary systems

[Aaron Dotter]

Hi Margaret,

>From your inlist, it looks like you’re not explicitly setting
‘which_atm_option’ in the controls section.  Thus, you get the default
simple_photosphere, which is not a good choice for low mass stars.

The atmosphere boundary condition and your choice of the
mixing_length_alpha have a significant influence on the Teff of your
models.  For a thorough discussion of this topic (using MESA) see

https://arxiv.org/abs/1805.04112

Cheers,
Aaron



On Wed, Jan 2, 2019 at 12:40 AM Margaret Streamer via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi MESA team,
>
>
>
> I recently had a paper published (Streamer, M., Ireland, M.J., Murphy,
> S.J., Bento, J., 2018. A window into δ Sct stellar interiors: understanding
> the eclipsing binary system TT Hor. Mon Not R Astron Soc 480, 1372-1383.
> https://doi.org/10.1093/mnras/sty1881) but I now have a more general
> query about the way MESA deals with binary systems.
>
> Inlists are attached.
>
> For TT Hor, I needed to change from solar metallicity to one higher
> (Z=0.0281, [M/H] =0.15) before I could match the temperature of the
> accretor in the evolutionary models to that of my binary model.  This
> difference was more than uncertainties of my binary model.
>
> I am now working on a different system which has similar masses, is also
> an Algol-type and has conservative mass transfer. I'm still using MESA
> version r-8845.
>
> Again I am finding that I need to increase the metallicity before I can
> match the temperature of my evolutionary models to the binary model.
>
> Both systems lie slightly above the galactic plane at 786pc (TT Hor) and
> 1190pc (current target), so a higher than solar metallicity is feasible.
>
> As the metallicity also affects the calculated pulsations, I need to be
> sure that this is a 'real' effect and not something I am doing wrong in my
> MESA modelling.
>
>
>
> Are any of the MESA team able to offer any advice or assurances in this
> matter?
>
>
>
> Many thanks for your time,
>
> Regards,
>
> Margaret
>
>
> _______________________________________________
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>
>
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