[Mesa-users] BD deuterium burning

[Jared Goldberg]

By default, MESA uses a very simplistic nuclear reaction network called "
basic.net" which does not include deuterium or its burning pathways. (See
https://docs.mesastar.org/en/latest/net/nets.html)

Even when using a network including deuterium, it does not initialize stars
with any deuterium by default, so you will need to explicitly set the
initial abundances including deuterium, in addition to making sure that
your nuclear reaction network contains deuterium burning.

In practice, this means that in the &star_job section of your inlist, you
will want to switch to a net that includes the appropriate reactions, for
example:

change_net = .true.
> change_initial_net = .true.
> new_net_name = 'pp_and_cno_extras.net'


You will then need to add deuterium by setting the initial composition or
relaxing the composition, e.g.

set_uniform_initial_composition = .true. (documentation:
> https://docs.mesastar.org/en/latest/reference/star_job.html#set-uniform-initial-composition
> )
> initial_h2 = 1d-5 ! or however much deuterium you want


and set the other initial abundances and abundance ratios as desired.

Cheers,
~Jared


On Wed, Aug 6, 2025 at 2:13 PM Matias Jones via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi Ealeal,
>
>
> Probably you need to modify the default rate_list.txt file (I guess is
> under data/rates_data/rate_tables/ dir) to include D burning. This worked
> for me.
>
> I am using an older MESA version, but probably this is also the case for v
> 23.5.1.
>
>
>
> Cheers,
>
>
>
> *--------------------------------------------------------------------*
> *Dr. Matía**s Jones F.*
>
> *VLT Operations Staff Astronomer *
> * ESPRESSO Instrument Scientist  *
> *SPHERE Instrument Scientist (IS2)*
>
>
> *European Southern Observatory Alonso de Córdova 3107, Vitacura, Santiago,
> Chile --------------------------------------------------------------------*
> ------------------------------
> *De:* Mesa-users <mesa-users-bounces at lists.mesastar.org> en nombre de
> Bear Ealeal via Mesa-users <mesa-users at lists.mesastar.org>
> *Enviado:* miércoles, 6 de agosto de 2025 12:26:50
> *Para:* mesa-users at lists.mesastar.org
> *Asunto:* [Mesa-users] BD deuterium burning
>
> This email was sent from outside of ESO from the address *[mesa-users-bounces at lists.mesastar.org
> <mesa-users-bounces at lists.mesastar.org>]*. If it looks suspicious, please
> report it to phishing at eso.org.
>
>
> Dear Mesa-users,
>
> I am working on MESA 23.5.1 and I run the example from test -suite named: "make_brown_dwarf"
> with no changes.
>
> mass and radius are:
>
> mass_in_gm_for_create_initial_model = 1.9892d31 ! 0.01 Msun;  m_jupiter =
> 1.8986d30; msun = 1.9892d33
>
>    radius_in_cm_for_create_initial_model = 3.5d10 ! 5 r_jupiter;
> r_jupiter = 6.9911d9.  ok for most brown dwarfs.
> The age when the inilist stops is 2Gyr.
>
> However, I do not get deuterium burning although I get *raw_rate_r_h2_pg_he3
> up to 1e18, t*he temperature at the center is too low also and there is
> no increase even not in the core in He3.
> Does someone have experience with BD in MESA, especially how to make the deuterium
> burn ?
>
> Thanks,
>
> Ealeal
>
>
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20250806/6aa9204d/attachment.htm>