[Mesa-users] An error in extras file for branching ratios of pp2 and pp3

[Francis Timmes]

thanks thomas.

fxt



> On Jan 24, 2020, at 2:49 AM, Steindl, Thomas <Thomas.Steindl at uibk.ac.at> wrote:
> 
> Hello again,
> 
> the run_star_extras i attached gives log_eps_nuc for the three branches in the basic net (r_he3_he3_to_h1_h1_he4, r34_pp2, and  r34_pp3). You can not just compare the profile output of pp with any of  the three as pp also involves other reactions (seehttp://cococubed.asu.edu/code_pages/burn_hydrogen.shtml <http://cococubed.asu.edu/code_pages/burn_hydrogen.shtml> ).
> But we can use the output of the three branches, integrate over the star and then calculate the ratios. With a quick model I found pp1 84.078%, pp2 15.903% and pp3 0.019%.  This rates compare not to bad for pp1 and pp2 (see again http://cococubed.asu.edu/code_pages/burn_hydrogen.shtml <http://cococubed.asu.edu/code_pages/burn_hydrogen.shtml> ). Adelberger et al ( https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.83.195 <https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.83.195> ) give 83.3% for pp1 and 16.7% for pp2 and pp3 which splits in 99.88% and 0.12% , giving a total of pp1 83.3% pp2  16.68%  and pp3 0.02% which is close to the values I found. I have no idea where the difference for the pp3 branch of this two comparisons arises from.
> 
> Now we have to keep in mind that we are using the basic.net <http://basic.net/> which handles the pp2 and pp3 chains as one reaction instead of 3 and 4. Using the net pp_extras.net <http://pp_extras.net/> would give us more detail in the calculation of the pp chain. One would have to include more reactions in the run_star_extras file but this should be straightforward. 
> 
> Additionally, this run_star extras gives the branching ratios as history output called branch_ratio_pp1, etc. computed in the way I described above. This would of course also need updating if you decide to go for a more detailed net. I hope this helps.
> 
> Thomas
> From: Mesa-users [mesa-users-bounces at lists.mesastar.org <mailto:mesa-users-bounces at lists.mesastar.org>] on behalf of Jaime Montes Norniella via Mesa-users [mesa-users at lists.mesastar.org <mailto:mesa-users at lists.mesastar.org>]
> Sent: Thursday, January 23, 2020 11:03 PM
> To: mesa-users at lists.mesastar.org <mailto:mesa-users at lists.mesastar.org>
> Subject: [Mesa-users] An error in extras file for branching ratios of pp2 and pp3
> 
> The last run.extras.f for the branching ratios of pp chain was a minor mistake: 
> The profile returns the log of eps_nuc  of pp2 and pp3 but the names of the new columns are eps_nuc. of  pp2 and pp3 
> The bug is corrected in this new file.
> 
> A big question is: 
> The values returned for a 1 solar mass star  and solar luminosity in mean sequence for log_eps_nuc of pp2 and pp3 are very high compared with the values returned in log10 of the ‘pp’ variable. Why?
> 
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