[Mesa-users] A Few Profile Output Questions

[Evan Bauer]

Hi Evan,

I think you’ll find the answer to your question in $MESA_DIR/star/public/star_data.inc
I’ll paste the comments at the beginning of that file here for convenience.

! Q: How is the "center" of a zone defined? is it the center by mass, or radius?
! A: Extensive variables (R, L, M, velocity) are defined at cell boundaries.
!    Intensive variables (T, rho, composition) are cell averages.
!    We use the cell average as an estimate of the point value at the cell center by mass.
!   The themo variables are cell averages since they are calculated as functions of the cell averages.
!   Note however that gradr and gradT are not thermo variables.
!   They are defined at cell boundaries and depend on both neighbors.
!   If you are comparing to results from a model that doesn't have staggered variables
!   (i.e., one that defines the intensive and extensive vars at the same place), then
!   you will need to adjust.   For example, to compare our sound speed profile to
!   published results, we interpolate the cell centered csound values to find values
!   at cell boundaries.

So the radius is the radius at the outer face of the shell, but the density is a cell average.

Cheers,
Evan


> On Jul 5, 2018, at 11:35 AM, Evan Cook <emc39 at students.calvin.edu> wrote:
> 
> Dear MESA users,
> 
> My name is Evan Cook, and I am working with a team of researchers using MESA. We have a few questions about the MESA output profiles. Is the radius reported for a given shell the inner radius, outer radius, or average radius of that shell? Is the mass reported for a given shell the mass of the star within the inner boundary of the shell or the mass of the star within the outer boundary of the shell (thus including the mass of the shell itself)? Lastly, is the density reported for a shell the density at the inner boundary, the outer boundary, or is it the average density of the shell?
> 
> -Evan
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