# Equation of state for solar modeling

On this page you can compute thermodynamics for conditions which exist inside the Sun. Different equations of state tables can be used, including SAHA-S equation of state.

>

## Select output values [help]

>Pressure P, dyn/cm^2
>Reduced pressure PI = P/(T*rho)
>Logarithmic partial derivative dlogP/dlogT (hi_t)
>Logarithmic partial derivative dlogP/dlogRHO (hi_rho)
>Logarithmic partial derivative dlogP/dlogX (hi_x)
>Expansion coefficient Q
>Specific internal energy U, erg/g
>Specific heat at constant volume Cv
>Specific heat at constant pressure Cp
>Logarithmic partial derivative dlogU/dlogRHO (ksi_rho)
>Sound speed, cm/sec (cs)

If you do not select anything, pressure will still be printed.

## Enter input data [help]

Enter here temperature T, density rho and chemical composition, one set of values per line (multiple lines are allowed). Chemical composition can be entered in four possible ways:

1) separate input fields for X and Z are used, each line contains only T and rho; example:

```2.17e6 0.18
```

2) each line contains T, rho, X and Z; separate input fields for X and Z are ignored; example:

```2.17e6 0.18 0.74 0.018
```

3) each line contains T, rho, X, Z(CNO), Z(Ne), Z(FeSi); separate input fields for X and Z are ignored; example:

```2.17e6 0.18 0.74 0.010 0.002 0.006
```

4) each line contains T, rho, X and 19 components for Z (C, N, O, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Ti, Cr, Mn, Fe, Ni); separate input fields for X and Z are ignored (this format is not very useful currently)

It is possible but not recommended to mix different numbers of Z components in one job. Input field size does not limit the amount of data entered; you can type or paste thousands of lines (10,000 lines tested with output size over 5MB).

Hydrogen mass fraction X (0.0 - 0.9):

Heavy elements mass fraction Z (0.0 - 0.02):

EOS tables may take up to 20 seconds to load! Please be patient...

Results [help]\n"; echo "

Using equation of state tables file \$EOS, " . "mixture \$mixture

\n"; \$cmd = "\$phys_path/hpcse.exe -e \$EOS -x \$X0 -z \$Z0 " . "-w \$phys_path/\$mixture P " . join (",", \$items); if (\$debug == 1) \$cmd .= " 2>&1"; \$tmp = "/tmp/eos." . getmypid() . "." . microtime(true); file_put_contents (\$tmp, \$input_data); if (\$debug == 1) echo "

running command \$cmd

"; putenv ("HPCSE_DATA=\$phys_path/data"); echo "
```\n";
system ("\$cmd <\$tmp");
echo "```