[mesa-users] Comparing OP_a09 vs. OP monochromatic track

[Ehsan Moravveji]

Thanks Aaron for your hint. 
I put the following block, in the extras_startup and in extras_controls, and the result did not change. 
I thought in this way, the Z scaling precedes specifying the individual mass fractions in the net.
In the following, I pass Z_ini = 0.014

      subroutine extras_controls(id, ierr)

         call crlibm_init
         call chem_init(isotopes_filename, ierr) 
         if (ierr /= 0) return 

      end subroutine extras_controls


      integer function extras_startup(id, restart, ierr)

         initial_zfracs = s% job% initial_zfracs
         select case(initial_zfracs)
            case(AGSS09_zfracs)
                  AGSS09_element_zfrac(:) = AGSS09_element_zfrac(:) * Z_ini
            case (A09_Prz_zfracs)
                  A09_Prz_zfrac(:) = A09_Prz_zfrac(:) * Z_ini
            case default
                ierr = -1
                write(*,*) 'Error: run_star_extras: extras_controls: requested initial_zfracs not needed now'
                return
         end select

      end function extras_startup

I guess this Z-scaling is internally done during the setting up of the run, before model_number 0.
Am I correctly following your hint?

Thanks for your help.
Ehsan.



> On 31 Jul 2015, at 23:19, Aaron Dotter <aaron.dotter at gmail.com> wrote:
> 
> Hi Esan,
> 
> I have one suggestion: Run the mono version again but this time force Z to be as defined in A09, instead of whatever it is exactly in your model.  By "force Z" I mean rescale the abundance array input to the mono routines such that H and He are unchanged but the other elements are rescaled by (1-X_H-X_He)*AGSS09_element_zfracs.  I hope that makes sense.
> 
> This is essentially what the tabulated opacities do.
> 
> I have done this before but only with low-T opacities calculated on the fly.  I can confirm that it resulted in a small shift in Teff similar to what you've shown.
> 
> Aaron
> 
> 
> On Saturday, August 1, 2015, Ehsan Moravveji <e.moravveji at gmail.com <mailto:e.moravveji at gmail.com>> wrote:
> Dear MESA users,
> I have computed two prototypical evolutionary tracks for a 7.5Msun star and Z=0.014 with Asplund et al. (2009) mixture, once setting
> 
>     initial_zfracs = 6
>     kappa_file_prefix = ‘OP_a09'
> 
> and another time turning on the monochromatic opacity (Mono) computations instead of using tables. Nothing else is changed.
> Mass loss and overshoot are also turned off, to make sure they do not intervene.
> I have attached my inlist and my modified net (that includes all 17 OP elements). I use version 7678 and MESASDK.
> 
> I notice that there is a significant shift of the evolutionary track towards higher log_Teff when using the Mono opacities. The reason is that the OP Mono opacity profile in this model is systematically below what is retrieved from tables.
> This surprises me, because the default OP_A09 table should (almost) mimic OP_a09 (with a difference that we need an interpolation in the latter case).
> 
> Has anyone seen this before?
> Is there a way to fix this difference? Am I making any mistake here in my inlists?
> 
> Best regards
> Ehsan.
> 

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