[mesa-users] [MESA]: Question Astrophysical Factor

[Robert Farmer]

Hi
You cant change the s-factor directly, however you can give mesa a file
with a customized set of nuclear reaction rates where you have changed the
s-factor yourself.

What you need to do (and example inlists and rate files can be found here
http://mesastar.org/results/properties-of-carbon-oxygen-
white-dwarfs-from-monte-carlo-stellar-models) follows:

Add this to the star_job section of your inlists

rate_tables_dir = './rate_tables'

Then make a folder rate_tables in your mesa work directory. Inside that
folder make a file rates_list.txt file with the following line:

r_h1_pg_h2     'r_h1_pg_h2.txt'

This says we want to alter the reaction h1+h1 -> h2 by looking for a file
called r_h1_pg_h2.txt where we will specify the rate as a function of
temperature

Then make a file called r_h1_pg_h2.txt in (rate_tables), where the first
two lines are:
#  r_h1_pg_h2 low rate:
# T8            RATE

Then you need to add a line with the number of rate points you have. Then
give the temperature in units of 10**8 K and a rate with one rate per line.
An example file might look like this though you will want many more rate
points than this:

#  r_h1_pg_h2 low rate:
# T8            RATE
5
0.01    0.0
0.5      1.0
1.0      2.0
10.5    3.0
100.0 10.0

Then run mesa and it should be using your new nuclear rate.

Rob



On Thu, Sep 15, 2016 at 4:25 PM, Gonçalo Andrade <gnmandrade at hotmail.com>
wrote:

> Dear Sir or Madam,
>
>
>
> I'm a MSc student and I'm doing my master thesis on asteroseismology of
> red giant stars. I'm using MESA to do models of these stars.
>
>
> I found this email on the MESA community website and I decided to try it
> as a last resource.
>
>
> The thing I need to do now in my project is to change the Astrophysical
> Factor (S-Factor) from the pp nuclear reaction to try to find out what
> changes does it have in the star and if these can be measured using
> seismology. The problem is I've been been searching online for some weeks
> and I can't find out how to change this factor. I've tried several things,
> the closest to what I wanted, I think, was to change the value on the file
> $MESA_DIR/rates/private/ratelib.f90 , but after that change the code no
> longer compiles...
>
>
> I a few words, I just need to change the S-Factor of the pp reaction.
>
>
>
> I thank you in advance and hope I'm not being inconvenient.
>
>
> Yours faithfully,
>
> Gonçalo Andrade
>
>
>
> ------------------------------------------------------------
> ------------------
>
> _______________________________________________
> mesa-users mailing list
> mesa-users at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/mesa-users
>
>
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