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How to Interpret your MESA-Web Calculation

Once your MESA-Web calculation has finished, you will have a directory which contains the data from your stellar model. We describe below how to interpret this data and also recommend the user visit the Tools & Utilities section to helpful resources to begin plotting your data.


Movies

MESA-Web calculations output mp4 videos constructed using PGSTAR, the live plotting software allowing a user to dynamically plot MESA output variables. The plots include: an abundance profile, Kippenhahn diagram, HR Diagram, Rotational profile, and T-Rho-P profile panels.

Diagrams are created at every fifth timestep and a mp4 is rendered using the snapshots the end of your MESA-Web calculation to provide a visual history of the overall evolutionary properties of your model. An example of a 15M star is shown below:




History Output

MESA-Web calculations contain a 'trimmed_history.data' file that contains items of interest about your stellar model at each timestep. The history output provides general information about the entire star at a particular timestep and are described below:

Column Datum Description
1 Model Number Number of model from the start of the calculation
2 Age (yr) Elapsed simulated time since the start of the calculation
3 Mass (M) Mass of the star in terms of Solar Mass
4 log L (L) Luminosity of the star in terms of log10 Solar Luminosity
5 log R (R) Radius of the star in terms of log10 Solar Radii
6 log Teff (K) Log10 effective temperature of the star
7 log Tc (K) Log10 temperature at the center of the star
8 log ρc (g cm-3) Log10 density at the center of the star
9 log Pc (dyn cm-2) Log10 pressure at the center of the star
10 ηc/kBT The electron chemical potential
11 X(1H) Hydrogen mass fraction at the center of the star
12 X(4He) Helium mass fraction at the center of the star
13 X(12C) Carbon 12 mass fraction at the center of the star
14 X(14N) Nitrogen 14 mass fraction at the center of the star
15 X(16O) Oxygen 16 mass fraction at the center of the star
16 X(18O) Oxygen 18 mass fraction at the center of the star
17 X(22Ne) Neon 22 mass fraction at the center of the star
18 τdyn (s) Dynamical timescale of the star
19 τkh (s) Kelvin-Helmholtz timescale of the star
20 τnuc (s) Nuclear timescale of the star
21 log Lpp (L) Log 10 luminosity due to all pp chain reactions
22 log LCNO (L) Log 10 luminosity due to CNO cycle
23 log L (L) Log 10 luminosity due to the triple alpha process
24 log LZ (L) Log 10 luminosity due to all nuclear burning excluding H and He
25 log Lν (L) Log 10 luminosity emitted by neutrinos (thermal and nuclear)
26 MHe (M) Amount of mass enclosed in outermost region where the Helium 4 mass fraction is greater than 0.01
27 MC (M) Amount of mass enclosed in outermost region where the Carbon 12 mass fraction is greater than 0.01
28 MO (M) Amount of mass enclosed in outermost region where the Oxygen 16 mass fraction is greater than 0.01
29 RHe (R) Radius of outermost region where the Helium 4 mass fraction is greater than 0.01
30 RC (R) Radius of outermost region where the Carbon 12 mass fraction is greater than 0.01
31 RO (R) Radius of outermost region where the Oxygen 16 mass fraction is greater than 0.01
32 ZAMScrit)i,surf Surface Average angular frequency divided by the Keplerian critical angular frequency at ZAMS
33 log Jtotal (g cm2s-1) Log 10 total angular momentum of the star at a particular model
34 Ωsurf (rad s-1) Surface Average angular frequency
35 vrot,surf (km s-1) Surface Average Rotational Velocity
36 dM/dt (M yr-1) Mass Loss Rate


Profile Output

MESA-Web calculations contain multiple 'profile$N.dat' files, where $N is the N'th profile of your calculation. MESA profile files contain information about each zone in your stellar model at a discrete timestep. A list explaining which profile corresponds to which timestep number can be found in the 'profiles.index' file from your calculation. The profile output provides general information about the entire star at a particular model number and are described below:



Column Datum Description
1 M (M) Mass coordinate of outer boundary of zone
2 R (R) Radius at outer boundary of zone
3 L (L) Luminosity at outer boundary of zone
4 P (dyn cm-2) Total pressure at center of zone (radiation + gas)
5 log ρ (g cm-3) Log 10 density at center of zone
6 log T (K) Log 10 temperature at center of zone
7 Eint (erg g-1) Internal energy
8 S/NAkB Specific entropy
9 Cp (erg g-1K-1) Specific heat capacity at constant total pressure
10 Γ1 (∂lnP/∂lnρ)S Gamma 1 at constant entropy
11 ad Adiabatic temperature gradient at constant entropy
12 μ Mean molecular weight per gas particle (ions + free electrons)
13 ne- (Ne- cm-3) Mean number of free electrons per nucleon
14 Pgas (dyn cm-2) Gas pressure at center of zone (electrons and ions)
15 Prad (dyn cm-2) Radiation pressure at center of zone
16 rad (∂lnT/∂lnρ)S Radiative temperature gradient
17 T (K g-1) Temperature gradient
18 vconv (cm s-1) Convection velocity
19 κ (cm2 g-1) Opacity measured at the center of zone
20 εnuc (erg g-1 s-1) Energy generation rate from all nuclear reactions excluding those from neutrino reactions
21 εpp (erg g-1 s-1) Energy generation rate from pp chain reactions
22 εCNO (erg g-1 s-1) Energy generation rate from CNO cycle
23 ε (erg g-1 s-1) Energy generation rate from triple alpha process
24 εν (erg g-1 s-1) Energy generation rate of neutrinos from all reactions
25 εcool (erg g-1 s-1) Non-nuclear-reaction neutrino losses
26 εgrav (erg g-1 s-1) Gravitational heating rate
27 X(1H) Hydrogen mass fraction
28 X(3He) Helium 3 mass fraction
29 X(4He) Helium 4 mass fraction
30 X(12C) Carbon 12 mass fraction
31 X(14N) Nitrogen 14 mass fraction
32 X(16O) Oxygen 16 mass fraction
33 X(18O) Oxygen 18 mass fraction
34 X(22Ne) Neon 22 mass fraction
35 η Electron Degeneracy Parameter
36 log ω (rad s-1) Log 10 specific angular frequency
37 vrot (km s-1) Rotational velocity at cell boundary
38 j (g cm2 s-1) Specific angular momentum
39 log Br (Gauss) Log 10 radial magnetic field
40 log Bφ (Gauss) Log 10 azimuthal magnetic field
41 log Dconv (cm2 s-1) Log 10 Dmix for regions where mix_type = convective_mixing