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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) Total mass of the star
4 log10 L (L) Luminosity of the star at the outermost cell
5 log10 R (R) Radius of the star at the outermost cell
6 log10 Teff (K) Log10 effective temperature of the star
7 log10 Tc (K) Log10 temperature at the center of the star
8 log10 ρc (g cm-3) Log10 density at the center of the star
9 log10 Pc (dyn cm-2) Log10 pressure at the center of the star
10 Xc(1H) Hydrogen 1 mass fraction at the center of the star
11 Xc(3He) Helium 3 mass fraction at the center of the star
12 Xc(4He) Helium mass fraction at the center of the star
13 Xc(12C) Carbon 12 mass fraction at the center of the star
14 Xc(14N) Nitrogen 14 mass fraction at the center of the star
15 Xc(16O) Oxygen 16 mass fraction at the center of the star
16 Xc(20Ne) Neon 20 mass fraction at the center of the star
17 Xc(24Mg) Magnesium 24 mass fraction at the center of the star
18 Xc(28Si) Silicon 28 mass fraction at the center of the star
19 Xc(32S) Sulfur 32 mass fraction at the center of the star
20 Xc(36Ar) Argon 36 mass fraction at the center of the star
21 Xc(40Ca) Calcium 40 mass fraction at the center of the star
22 Xc(44Ti) Titanium 44 mass fraction at the center of the star
23 Xc(48Cr) Chromium 48 mass fraction at the center of the star
24 Xc(52Fe) Iron 52 mass fraction at the center of the star
25 Xc(54Fe) Iron 54 mass fraction at the center of the star
26 Xc(56Fe) Iron 56 mass fraction at the center of the star
27 Xc(56Ni) Nickel 56 mass fraction at the center of the star
28 ηc/kBT The electron chemical potential at the center of the star
29 Ye,c The ratio of electrons to baryons at the center of the star
30 Sc/(kB baryon) The entropy at the center of the star
31 ξm=2.5 (M) Compactness parameter
32 τdyn (s) Dynamical timescale of the star
33 τkh (s) Kelvin-Helmholtz timescale of the star
34 τnuc (s) Nuclear timescale of the star
35 log10 Lpp (L) Log10 luminosity due to all pp chain reactions
36 log10 LCNO (L) Log10 luminosity due to CNO cycle
37 log10 L (L) Log10 luminosity due to the triple alpha process
38 log10 LH (L) Log10 luminosity due to all H nuclear burning
39 log10 LHe (L) Log10 luminosity due to all He nuclear burning
40 log10 LZ (L) Log10 luminosity due to all nuclear burning excluding H and He
41 log10 Lν (L) Log10 luminosity emitted by neutrinos (thermal and nuclear)
42 MHe (M) Amount of mass enclosed in outermost region where the Helium 4 mass fraction is greater than 0.01
43 MC (M) Amount of mass enclosed in outermost region where the Carbon 12 mass fraction is greater than 0.01
44 MO (M) Amount of mass enclosed in outermost region where the Oxygen 16 mass fraction is greater than 0.01
45 MSi (M) Amount of mass enclosed in outermost region where the Silicon 28 mass fraction is greater than 0.01
46 MFe (M) Amount of mass enclosed in outermost region where the Iron 56 mass fraction is greater than 0.01
47 RHe (R) Radius of outermost region where the Helium 4 mass fraction is greater than 0.01
48 RC (R) Radius of outermost region where the Carbon 12 mass fraction is greater than 0.01
49 RO (R) Radius of outermost region where the Oxygen 16 mass fraction is greater than 0.01
50 RSi (R) Radius of outermost region where the Silicon 28 mass fraction is greater than 0.01
51 RFe (R) Radius of outermost region where the Iron 56 mass fraction is greater than 0.01
52 |vmax| (cm s-1) Absolute value of maximum velocity of the star
53 ZAMScrit)i,surf Surface Average angular frequency divided by the Keplerian critical angular frequency at ZAMS
54 log10 Jtotal (g cm2s-1) Log10 total angular momentum of the star at a particular model
55 Ωsurf (rad s-1) Surface Average angular frequency
56 vrot,surf (km s-1) Surface Average Rotational Velocity
57 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 log10 ρ (g cm-3) Log10 density at center of zone
6 log10 T (K) Log10 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 Ye Specific ratio of electrons to baryons
15 Pgas (dyn cm-2) Gas pressure at center of zone (electrons and ions)
16 Prad (dyn cm-2) Radiation pressure at center of zone
17 rad (∂lnT/∂lnρ)S Radiative temperature gradient
18 T (K g-1) Temperature gradient
19 v (cm s-1) Velocity at outer boundary of zone
20 vconv (cm s-1) Convection velocity
21 κ (cm2 g-1) Opacity measured at the center of zone
22 εnuc (erg g-1 s-1) Energy generation rate from all nuclear reactions excluding those from neutrino reactions
23 εpp (erg g-1 s-1) Energy generation rate from pp chain reactions
24 εCNO (erg g-1 s-1) Energy generation rate from CNO cycle
25 ε (erg g-1 s-1) Energy generation rate from triple alpha process
26 εν (erg g-1 s-1) Energy generation rate of neutrinos from all reactions
27 εcool (erg g-1 s-1) Non-nuclear-reaction neutrino losses
28 εgrav (erg g-1 s-1) Gravitational heating rate
29 X(1H) Hydrogen mass fraction
30 X(3He) Helium 3 mass fraction
31 X(4He) Helium 4 mass fraction
32 X(12C) Carbon 12 mass fraction
33 X(14N) Nitrogen 14 mass fraction
34 X(16O) Oxygen 16 mass fraction
35 X(20Ne) Neon 20 mass fraction
36 X(24Mg) Magnesium 24 mass fraction
37 X(28Si) Silicon 28 mass fraction
38 X(32S) Sulfur 32 mass fraction
39 X(36Ar) Argon 36 mass fraction
40 X(40Ca) Calcium 40 mass fraction
41 X(44Ti) Titanium 44 mass fraction
42 X(48Cr) Chromium 48 mass fraction
43 X(52Fe) Iron 52 mass fraction
44 X(54Fe) Iron 54 mass fraction
45 X(56Fe) Iron 56 mass fraction
46 X(56Ni) Nickel 56 mass fraction
47 η Electron Degeneracy Parameter
48 log10 ω (rad s-1) Log10 specific angular frequency
49 vrot (km s-1) Rotational velocity at cell boundary
50 j (g cm2 s-1) Specific angular momentum
51 log10 Br (Gauss) Log10 radial magnetic field
52 log10 Bφ (Gauss) Log10 azimuthal magnetic field
53 log10 Dconv (cm2 s-1) Log10 Dmix for regions where mix_type = convective_mixing
54 log10 Dsemi (cm2 s-1) Log10 Dmix for regions where mix_type = semiconvective_mixing
55 log10 Dovr (cm2 s-1) Log10 Dmix for regions where mix_type = overshoot_mixing
56 log10 Dthrm (cm2 s-1) Log10 Dmix for regions where mix_type = thermohaline_mixing