[mesa-users] oscillation data

Bill Paxton paxton at kitp.ucsb.edu
Sun Jun 23 16:41:21 EDT 2013

On Jun 23, 2013, at 1:09 PM, Ehsan Moravveji wrote:

> Hello Bill,
> Just got a chance to take a look at the way you produced a pulsation_info file from extras_check_model.
> There is a difference regarding the epsilon_nuc term and its derivatives with the way it is implemented in /private/pulsation_info.f, and I find that you are subtracting the contribution from other heat sources.
> I was expecting to have this already taken care of when s% eps_nuc(k) is evaluated.

Hi Ehsan,

It is always exciting to try to figure out what is meant by those little greek symbols -- "alpha" is another fun one.
In this case "epsilon" for non-adibatic pulsation is the one in question -- what exactly should be included?
I've Cc'd Rich this time in case he'd like to help us out.

In the mesa/star energy conservation equation we have dL/dm = eps_grav + eps_burn
where eps_grav = -T*Ds/Dt
and eps_burn = eps_nuc - non_nuc_neu + extra_heat + irradiation_heat.
eps_nuc is the energy from nuclear reactions with nuclear neutrinos subtracted.
non_nuc_neu is the energy leaving as neutrinos created by non-nuclear-reaction sources.
extra_heat is usually 0, but the user can specify it to do "stellar engineering" such as tidal heating in binary.
irradiation_heat is also usually 0, but it can be set to model heating from a binary companion.
If you are only concerned about cases in which non-nuclear neutrinos are irrelevant,
and you aren't setting extra_heat or irradiation_heat, this reduces epsilon to eps_nuc.

In the code I sent recently, epsilon = eps_burn.  That's what GYRE uses.

However, as you note, there is still the question of what "epsilon" is for FGONG and OSC.
When I implemented those, I was using the File Formats pdf from http://www.astro.up.pt/corot. (attached)
In the "Notation" section, it says epsilon is "rate of energy generation per unit mass".
In the FGONG section, it includes "epsilon" as VAR(9) at each point.
In the OSC section, it has VAR(9) = eps_t = eps_nuc + eps_grav, nuclear plus gravitational energy production.
In the mesa code in pulsation_info.f, it sets VAR(9) = eps_nuc + eps_grav.


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