[mesa-users] issue with OP AGSS09

Sat Oct 12 02:39:13 EDT 2013

Hi,

It solves the problem in my opinion. Yesterday I found the same, i.e. that
OP A09 extends only to logT=8 (and all other go to 8.7), but thought it is
a job of preprocessor to correctly blend the opacities at lower logT, and
asked Bill about that to make sure. Now I see that preprocessor does not
care about blending, just prepares the opacities in MESA format and kap
module makes blending. Therefore, am I right that
- at the moment using OP A09 for any problem dealing with large log T is
simply wrong?
- can we simply fix this and tell kap module to make blending at lower
logT? (does the source of opacities at large  logT extend also down to
logT=8 and is reliable there?)
- does anyone know why the OP web application now produces the results only
to logT=8, while for OP GS98 it was possible to go logT=8.7 (how OP gs98
file was prepared: with web application or OPCD software?)
Cheers,
Radek


2013/10/12 Aaron Dotter <aaron.dotter at gmail.com>

> Hi again,
>
> Further inspection shows that the kap module isn't properly dealing with
> the different temperature limits of OP vs. OPAL.
>
> OP only goes up to logT=8; OPAL goes up to logT=8.7.  In the MESA opacity
> files based on OP data the values for logT > 8 are set 9.999.  In the kap
> module the limits where the opacity is blended between high-T tables and
> compton is between 8.2 and 8.69.  Using the OP opacities, rather than OPAL,
> at high temperatures would encounter the missing data 9.999s.
>
> He-burning is relevant at these temperatures and, thus, this ought to be
> Type2 enhanced C and O territory anyway, but the choice to use those or not
> is in the user's hands.
>
> Aaron
>
>
> On Sat, Oct 12, 2013 at 11:44 AM, Aaron Dotter <aaron.dotter at gmail.com>wrote:
>
>> Hi all,
>>
>> With regard to Jakub's first email, an important consideration is that
>> He-burning models really should be using Type2 opacities to account for the
>> production of excess C and O.  The inlist provided does not seem to include
>> the Type2 tables.
>>
>> I have also compared the headers for the OP A09 tables that are in the
>> current mesa/kap/preprocessor/kap_input_data/OP directory.  These files are
>> called
>>
>> 1. A09.OP17
>> 2. A09_Przybilla.OP17
>>
>> The OPAL format, which OP mimics, lists the input abundances for metals
>> near the top of the file.  Just looking at the input abundances shows that
>> the second file is inconsistent with A09 abundances (and should not be
>> used).  The first is alright.  We have the issue that OPAL includes more
>> elements than OP in the opacity calculation, so that there will be larger
>> discrepancies between OP abundances and OPAL abundances even for the
>> correct input mixture.
>>
>> For reference, the OPAL table for A09 is "correct" in the sense that it
>> matches the actual values given in the table of Asplund et al. (2009) for
>> all elements present.  It can be found at kap_input_data/opal/A09opal.
>>
>> Aaron
>>
>>
>>
>>
>> On Sat, Oct 12, 2013 at 5:59 AM, Bill Paxton <paxton at kitp.ucsb.edu>wrote:
>>
>>> Hi Craig,
>>>
>>> Thanks for the pointer.   Before we get to that, we need to wait for
>>> Radek & Jakub to check the mesa opacity tables to see if there is a problem
>>> in them.
>>>
>>> Bill
>>>
>>>
>>>
>>>
>>> On Oct 11, 2013, at 11:47 AM, Craig Wheeler wrote:
>>>
>>> > http://adsabs.harvard.edu/abs/2012A%26A...542A...1L
>>> >
>>> > Might be relevant.
>>> >
>>> > Craig
>>> >
>>> > On 10/11/13 1:22 PM, Bill Paxton wrote:
>>> >> Hi Jakub,
>>> >>
>>> >> Lovely!  The jumps in core He abundance from 1% to 3% suggest
>>> instabilities during the "death" of the core He burning convection zone.
>>>  Please check that -- make plots of size of core convection zone during
>>> this time and share them with us.  I expect that the convection dies out
>>> when core He drops to 1%, but then the core temp rises and you get a burst
>>> of convection from that.  The convection briefly reaches up into He rich
>>> material and raises the center abundance up to 3% and that lets the core
>>> temperature drop.  Then the cycle repeats until the convective bursts can
>>> no longer bring down more He.
>>> >>
>>> >> Since the convection will be sensitive to opacities, the change from
>>> GS98 to A09 might be enough to trigger this.   And of course overshooting
>>> during He burning can go unstable as you well know.  You have overshooting
>>> above he burning turned on:
>>> >>       overshoot_f_above_burn_he = 0.010
>>> >> so that might also be contributing to this.   What happens to this
>>> when you run without overshooting?  I expect that will cause you grief in
>>> other things, but specifically what effect does it have on these
>>> instabilities in core he burning?
>>> >>
>>> >> My guess is that the A09 tables are fine.  They are just pushing you
>>> over the cliff with an overshooting related instability during the final
>>> stage of core He burning.    But I'm suspicious of the use of overshooting
>>> during core He burning anyway -- it has been very unstable when I've tried
>>> it.   But let's see -- maybe it has nothing to do with what you are getting
>>> here.
>>> >>
>>> >> Another question -- you are dealing with opacities in the C/O ashes
>>> of He burning, but you are not using Type2 opacities.  Why not?  Have you
>>> experimented and found that there was no difference?  That would be a
>>> surprise.
>>> >>
>>> >> -Bill
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> On Oct 11, 2013, at 10:58 AM, Jakub Ostrowski wrote:
>>> >>
>>> >>> 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
>>> >>>
>>> >>> <LHe-Yc-15m-op-z0.01.pdf>
>>> >>> <15m-z0.01-op-opal.pdf>
>>> >>> <inlist_15m_op_f0010_z001>
>>> >>
>>> >>
>>> ------------------------------------------------------------------------------
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>>> > --
>>> > J. Craig Wheeler
>>> > Department of Astronomy
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>>> > http://www.smashwords.com/books/view/127749
>>> > http://www.smashwords.com/books/view/178104
>>> > http://www.amazon.com/The-Krone-Experiment-ebook/dp/B008Y6L3VW
>>> > http://www.amazon.com/Krone-Ascending-ebook/dp/B00926QEGW
>>> > http://www.amazon.com/The-Q-Man-1-ebook/dp/B00AFKJYKC
>>> >
>>>
>>>
>>>
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>>
>>
>
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