Re: mesa-users] FGONG and pulsation output from star

[Bill P. <pa...@ki...>]

Ehsan,

one more thing about the pulsation output from mesa/star --
please understand that this is a part of the code that has
not had significant use yet.   so there will be bugs!
if you come across something that looks weird, it is
probably something that has never been checked before.

so let me know when you run into problems and hopefully
we can find fixes.   for example, yesterday Mike pointed
out that I had left out a factor of r in one of the FGONG
terms!   easy to fix, but I'm not an FGONG user so I hadn't
found the problem on my own.

One other thing to be careful about: as you know mesa/star
splits the model into cells.  Each variable is associated with
a cell.  Extensive variables (M, R, L) are defined at the outer
boundary of the cell.  Intensive ones (lnT, lnRho, composition)
are defined as cell averages -- which is approximately the same
as saying that they are the cell center values.   So there is
a small but significant offset in location for R vs. Rho for example.

For doing precision pulsation work, you need to get values from
the same location -- so for example in the FGONG output, 
I evaluate everything at the cell boundaries, so I need to interpolate
T, Rho, composition, and such from the adjacent cell centers.



Cheers,
Bill