[Mesa-users] Energy conservation on the main sequence

[Pablo Marchant]

Things do seem to match at the beginning, which I assume is the pre-MS. So
I'm guessing you're missing something related to nuclear reactions. Maybe
L_neu?

Easier to check with inlists at hand for sure.

Cheers

On Sun, Feb 17, 2019 at 2:21 PM Bill Paxton <paxton at kitp.ucsb.edu> wrote:

> Hi Rich,
>
> Please provide inlists etc so we can play along with you, starting by
> being able to reproduce your plots.
>
> Thanks,
> Bill
>
> > On Feb 17, 2019, at 12:14 PM, RICHARD H D TOWNSEND via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
> >
> > Hi folks --
> >
> > I'm writing to ask about energy conservation on the main sequence, for a
> solar-mass star. I'm not yet sure whether this is more of a question about
> stellar evolution, or about MESA.
> >
> > In the attached figure, I plot two quantities as a function of time:
> >
> > tot_E_change -- the total energy change across each timestep
> > total_energy_sources_and_sinks -- the total energy sources/sinks across
> each timestep
> >
> > For this evolutionary stage, total_energy_sources_and_sinks is
> practically identical to (L_nuc - L)*dt, where L_nuc is the nuclear
> luminosity, L the surface luminosity, and dt the timestep.
> >
> > My understanding is that the two quantities should align perfectly --
> the net energy gain/loss is matched by a change in the star's total energy
> (which, according to the virial theorem, will result in an
> expansion/contraction). But that's clearly not what we see; while
> total_energy_sources_and_sinks is always positive (with the exception  of
> the ZAMS), the tot_E_change is initially negative and only becomes positive
> later on in the evolution.
> >
> > I'm clearly missing something important, but I'm not sure what. So, can
> anyone help clarify what's going on?
> >
> > cheers,
> >
> > Rich
> >
> > <energe-change.pdf>_______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
>
> _______________________________________________
> mesa-users at lists.mesastar.org
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>
>

-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
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