[Mesa-users] Hydrogen core mass and radius

[Pedro Nuno David Gomes]

Hi Aaron, 

I'll have a look into it. Thank you for your reply, 

Pedro 

A 2018-08-22 19:47, Aaron Dotter escreveu:

> Hi Pedro, 
> 
> Please include mesa-users when you reply to emails on this list. 
> 
> The He core (he_core_radius and he_core_mass) is defined by the H mass fraction falling below some limit. 
> 
> For the case you are interested in, we can't use the above definition, and I don't think there is anything in history columns that will give you exactly what you want.  But have a look at these: 
> 
> !## regions of strong nuclear burning 
> 
> ! 2 zones where eps_nuc > burn_min1 erg/g/s 
> ! for each zone have 4 numbers: start1, start2, end2, end1 
> ! start1 is mass of inner edge where first goes > burn_min1 (or -20 if none such) 
> ! start2 is mass of inner edge where first zone reaches burn_min2 erg/g/sec (or -20 if none such) 
> ! end2 is mass of outer edge where first zone drops back below burn_min2 erg/g/s 
> ! end1 is mass of outer edge where first zone ends (i.e. eps_nuc < burn_min1) 
> ! similar for the second zone 
> 
> epsnuc_M_1 ! start1 for 1st zone 
> epsnuc_M_2 ! start2 
> epsnuc_M_3 ! end2 
> epsnuc_M_4 ! end1 
> 
> epsnuc_M_5 ! start1 for 2nd zone 
> epsnuc_M_6 ! start2 
> epsnuc_M_7 ! end2 
> epsnuc_M_8 ! end1 
> 
> ! you might want to get a more complete list of burning regions by using the following 
> 
> !burning_regions <integer> 
> ! the <integer> is the number of regions to report 
> ! there will be 2*<integer> columns for this in the log file, 2 for each region. 
> ! the first column for a region gives int(sign(val)*log10(max(1,abs(val)))) 
> ! where val = ergs/gm/sec nuclear energy minus all neutrino losses. 
> ! the second column for a region gives the q location of the top of the region 
> ! entries for extra columns after the last region in the star will have a value of -9999 
> ! all regions are included starting from the center, so the bottom of one region 
> ! is the top of the previous one. 
> ! since we start at the center, the bottom of the 1st region is q=0 and top of last is q=1. 
> 
> ! the columns in the log file will have names like 'burn_type_1' and 'burn_qtop_1' 
> 
> ! if the star has too many regions to report them all, 
> ! the smallest regions will be merged with neighbors for reporting purposes only. 
> 
> Otherwise you will have to make your own definition and add it to your history file via run_star_extras.  There are tutorials,  
> 
> http://mesa.sourceforge.net/run_star_extras.html#adding-history--profile-output 
> 
> Good luck! 
> 
> Aaron 
> 
> On Wed, Aug 22, 2018 at 1:21 PM Pedro Nuno David Gomes <pedro.david.gomes at ist.utl.pt> wrote: 
> 
> A 2018-08-22 17:24, Aaron Dotter escreveu: 
> Hi Pedro, 
> 
> This will depend upon how you define the hydrogen core.  So, how do you define it? 
> 
> Aaron 
> 
> On Wed, Aug 22, 2018 at 11:26 AM Pedro Nuno David Gomes via Mesa-users <mesa-users at lists.mesastar.org> wrote: Dear MESA users,
> 
> Regarding the evolution of Main Sequence stars, how can I obtain as 
> output the fractional mass and radius of the hydrogen core?
> 
> Thank you for your attention.
> Regards,
> 
> Pedro
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users

Hi Aaron, 

Thank you for your reply. 

I consider the core of a MS star to be the region in which nuclear
fusion of hydrogen into helium is occuring. In what concerns MESA, I
haven't defined anything regarding the core (sorry if I'm missing
something obvious, but I only started working with MESA recently).  

Since the radius of the He core can be obtained for other evolution
stages by uncommenting "he_core_radius" in history_columns.list, I
imagined there could be something similar for H core. I'm trying to
evolve a 1.5M_sun star until the subgiant branch. 

Thank you. Cheers, 

Pedro
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