[Mesa-users] Question about mass fraction

[Farag, Ebraheem Khaled]

I'm a little confused by your graphic, but here is my understanding:


Abundances in MESA, when output in profiles, are listed as the fraction of total mass in each radial shell of the star. By this, I mean that if you output the abundance of He4 at zone 754, then that abundance will be the fraction of He4 in zone 754, not the entire model.


If you'd like the total mass fraction of a given element in the star at a given point in time, there are parameters in the history profiles which can output this for you.


TLDR: profile_columns -> can output He4 abundance as a function of mass or radius at a given time step in the stars history

           history_columns-> can output total He4 abundance of the entire star at a given time step in the stars history.


Should you decide, you can also integrate your profile_columns output to produce history columns values.


-refer to the $MESA_DIR/star/defaults/ and you'll probably find the output you're looking for in history_columns.list or profile_columns.list. Be careful, editing these files will change the output for all MESA/star runs, unless you make a local copy in your work directory and modify it there, as well as the pointer in your work/inlist file that points to these two files.


I hope that was helpful, cheers!


-Ebraheem

________________________________
From: Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of d10631026陳瑜安 <d10631026 at gapps.fg.tp.edu.tw>
Sent: Wednesday, May 15, 2019 7:32:26 PM
To: mesa-users at lists.mesastar.org
Subject: [Mesa-users] Question about mass fraction

Dear MESA Users,

I'm not sure whether the meaning of mass fraction is like what I draw in the picture.
I would like to ask about the meaning of mass fraction.

Thank you,
Ann
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