[mesa-users] TP-AGB and Post-AGB Mass Loss Issues

Thu Feb 11 21:00:36 EST 2016

Hi Ian, 
another set of questions are answered in review publications, such as these:
http://adsabs.harvard.edu/abs/2013pss4.book..397H
http://adsabs.harvard.edu/abs/2005ARA%26A..43..435H
http://adsabs.harvard.edu/abs/2006PASP..118..183W
Forgive me the author bias, but these sprung to mind most quickly.
Best, Falk.

> On Feb 11, 2016, at 5:42 PM, Francis Timmes <fxt44 at mac.com> wrote:
> 
> many of your questions could be answered by 
> you studying the source code. have you looked?
> 
> fxt
> 
> 
> 
> 
> 
>> On Feb 11, 2016, at 6:10 PM, Ian Foley <ifoley2008 at gmail.com> wrote:
>> 
>> As part of my personal education of Stellar Evolution, I have been
>> running the 1M pre ms to wd test suite case up to 9M and trying out
>> and learning about the inlist.
>> 
>> The big issue I see is to understand how mass loss is applied and its
>> relationship to the thermal pulses.
>> 
>> Very evident is that if I increase the RGB and AGB scaling factors ( I
>> have tried from 0.1 up to 8) it flattens out and reduces the number of
>> thermal pules I suspect this is because as we increase the mass loss
>> via the mass loss formulae, the larger and more frequent TP's are not
>> needed to remove the mass.
>> 
>> This has led me to try to find answers to the following questions.
>> 
>> 1. Is the mass loss formula applied to every zone to compute the loss?
>> If yes, why isn't mass loss calculated by using the radial velocity
>> and computing the amount of matter expelled through the star's outer
>> zone. If no, how is the formula applied?
>> 
>> 2. Is the mass loss formula applied only to H? Or is it applied to He
>> and others as well?
>> 
>> 3. I have been primarily using the Reimer and Blocker mass loss
>> formula which is I think a heuristic formula determined by
>> experimental observations. However, it does seem to be applied fairly
>> independently of the actual stellar evolution equations. Since we
>> don't know very well from experiment the number and scale of the TP's
>> how can we know what is a good scaling factor to use.
>> 
>> 4. In relation to the new solar wind additions in r8118 over r7624
>> it's not quite clear to me what is the relation between the Reimer and
>> Blocker terms and turning on and off the the cool wind dependent on
>> temperature. Are the Reimer and Blocker factors still needed and the
>> cool wind temperature terms just configure when they are activated?
>> 
>> 5. I have similar issues with the convection overshooting. Although it
>> seems likely to be important it seems we have no idea of the
>> appropriate number to apply. And, like mass loss, the bigger the
>> factors you choose the more it dampens the TP's.
>> 
>> 6. How is the mass loss formula's applied in the post-AGB phase? Does
>> the Blocker term just switch off at some point and if so when? Why
>> does it seem that there is no He loss in the post-AGB phase?
>> 
>> 7. I find it very strange that in the post-AGB phase the lg_LH term in
>> the terminal output is still up close to the total lg_L even when
>> there is almost no hydrogen left and what hydrogen there is in the
>> outer zones of the envelope.
>> 
>>      step    lg_Tcntr    Teff       lg_LH     lg_Lnuc     Mass
>> H_rich
>> H_cntr     N_cntr     Y_surf     X_avg     eta_cntr  zones retry
>>  lg_dt_yr    lg_Dcntr    lg_R       lg_L3a    lg_Lneu     lg_Mdot
>> He_core    He_cntr    O_cntr     Z_surf     Y_avg     gam_cntr  iters
>> bckup
>>    age_yr    lg_Pcntr    lg_L       lg_LZ     lg_Psurf    lg_Dsurf
>> C_core
>> C_cntr     Ne_cntr    Z_cntr     Z_avg     v_div_cs     dt_limit
>> 
>>     39400   8.211499  2.889E+04   4.255626   4.354482   0.985786
>> 0.000116   0.000000   0.000000   0.374091   0.000065  49.353686   2183
>> 5037
>> -5.801543   7.277248   0.753659   3.545685   3.889458  -4.012795
>> 0.985670   0.000000   0.579524   0.020125   0.001666   7.754729      6
>>   31
>> 3.5571E+07  24.321104   4.303656   3.038122   3.281056 -10.342147
>> 0.982096   0.394597   0.001949  1.000E+00  9.983E-01  0.000E+00
>> varcontrol
>> 
>> Is this OK or is there a problem with the software?
>> 
>> 
>> I would be very grateful for any help in answer to these questions
>> Ian
>> 
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--
Falk Herwig
Dept of Physics & Astronomy, U of Victoria
fherwig at uvic.ca, tel: +1 (250) 721-7743