[mesa-users] Opacity Feature Request

Ehsan Moravveji e.moravveji at gmail.com
Mon Jan 19 14:21:14 EST 2015

Dear Bill,

I have lately been trying to modify the shape of the opacity profile using the s% extra_opacity_factor vector from the 
default_other_opacity_factor() hook in run_star_extras in a consistent way.
Tracing back the effect of  s% extra_opacity_factor on the structure variables, I arrive at line 168 to 170 of /mesa/star/private/opacities.f

        s% opacity(k) = s% opacity(k)*opacity_factor               (1)
        s% d_opacity_dlnd(k) = s% opacity(k)*dlnkap_dlnd     (2)
        s% d_opacity_dlnT(k) = s% opacity(k)*dlnkap_dlnT     (3)

Because s% d_opacity_dlnd(k) and s% d_opacity_dlnT(k) are internally used in other modules like hydro_eqns.f90 and hydro_mtx.f90, I think 
for the sake of consistency, they should also be allowed to be modified by a user supplied factor. The reason is that after multiplication of the opacity
with any arbitrary factor (here, s% opacity_factor), the differentials w.r.t. T and Rho are not adapted to this change.
Please correct me if I am wrong.

I think for the sake of consistency, we need two additional multipliers, for the right-hand-sides of Eq. (2) and (3) above.
If you agree with my points of reasoning, can you please add this as a new feature?

Best regards

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