[mesa-users] Fwd: issue with OP AGSS09

Fri Oct 11 14:33:19 EDT 2013

Sorry if you get this message twice. The first message was bounced back
because I used wrong e-mail account.

Hi,

I checked the issue with OP a09 reported by Jakub and find the same
problems. Using the opacity procedures from the Warsaw-New Jersey code and
opacity tables generated for WNJ that I implemented in MESA (as other_kap)
I got some hints what might be wrong. Below I report my findings.

I focused on Z=0.008 and Y=0.23. I attach the inlist for my computations
(MESA 5456, sdk, run on a unix cluster). The only things I have changed in
this inlist to get different tracks, are mass and opacities.

 evol_MESAopac_OPALgn93.eps shows the computations with MESA opacities and
OPAL gn93. It is for reference only. It seems everything is fine here and
tracks look as expected.

evol_MESAopac_OPa09.eps shows the computations with MESA opacities and OP
A09 (kappa_file_prefix = 'OP_a09',  kappa_lowT_prefix = 'lowT_fa05_a09p').
Computations are extremely slow now (and extend to 12 MS only, higher
masses are still on the way). There are no loops and the tracks for 10 and
12 solar masses are very erratic at the tip of RGB.

evol_WNJopac_OPa09.eps - these are computations with MESA opacities
replaced by WNJ opacities - both opacity interpolation procedures and
opacity tables are from WNJ. It is OP and A09. Now computations extend to
18 solar masses. Except for track for 12Ms (no loop) everything looks fine
and similar to the OPAL gn93 case.

evol_MESAopac_WNJopac_OPa09.eps - in this plot I compare the tracks
computed with MESA and WNJ opacities, both for OP and A09. It seems that
for main sequence and RGB the agreement is very good. The differences are
small and may be attributed to different opacity procedures. But once
helium starts burning the huge differences arise.

Conclusion:
I think something must be wrong with MESA calculations with OP A09
opacities. I see three possible explanations:

1. I did something wrong generating the OP tables. Today Jakub repeated the
calculations and we get the same results. OR slightly different results. It
turns that it makes a difference to this OP www application if it gets a
numbers like 2.44 or 2.440 (0 on a third place). The produced tables are
then somewhat different but the differences are very small and likely not
play a role here. If we consistently provide the abundances with 2 digits
after the comma (no 0 on a third place) we get the same results.

2. OP server did something wrong. I don't know how to check this.

2a. Bill, please recall the e-mails I have sent you about differences
between OPCD calculations and OP-www calculations. There were differences
for extreme cases - low R for which OPCD does not generate output (and some
other stuff was put in there by hand in the Warsaw tables) but OP-www does
generate output. But there were also differences for (not so high) T  - I
attach the comparison file (comparison.ps) once again - see the last two
plots. Maybe these differences are responsible for such behaviour and
opacities we have in WNJ simply work better? In any case both the stuff put
in there in Warsaw/OPCD and in OPwww is not or poorly described.

3. Maybe something went wrong during processing the OP tables to MESA
format. Can you check this point Bill?

4. The suggestion by Bill, I have just read - the effect is real. But then
why with WNJ opac and its tables everything goes fine? Maybe the effect is
very sensitive to fine details of the opacity procedures/tables.

Cheers,
Radek

2013/10/11 Jakub Ostrowski <ostrowski at astro.uni.wroc.pl>

> Hi,
>
> I'd like to point out an unusual behavior that happens with calculations
> which use the recently implemented OP AGSS09 opacity tables. I calculated
> models within mass range of 3 - 20 MS and for metallicity between 0.01 and
> 0.02 and there are problems with every model.
>
> First of all, with OPAL AGSS09, OPAL GS98 and OP GS98 there is a helium
> blue loop for every calculated track while for OP AGSS09 there is none for
> any of them. This behavior itself doesn't necessary mean that something is
> wrong, but the other thing does: after the core helium abundance drops
> below about 1% it suddenly rises to about 3% and the energy produce from
> helium burning increases. Then it repeats itself again for a dozen of times
> or so. I attached a plot that shows this behavior for 15Ms and Z = 0.01,
> but this problem exists for every single model I calculated with OP AGSS09.
>
> I discussed the problem with Radek who provided the tables. He confirmed
> that the problem is real and I'm sure he will soon provide his ideas.
>
> My environment: MESA v5456 compiled with SDK on OS X 10.8.5. You can find
> the attaches inlist. The only things I changed there are opacity tables,
> mass and metallicity.
>
> Cheers,
> Jakub
>
>
>
>
>
>
>
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