Physical constants
Constants used throughout VULCAN, defined in phy_const.py. All values are in cgs units,
taken from the astropy package.
| Symbol | Name | Value | Units |
|---|---|---|---|
kb |
Boltzmann constant | 1.38064852e-16 |
erg K\(^{-1}\) |
Navo |
Avogadro's number | 6.02214086e23 |
mol\(^{-1}\) |
hc |
Planck constant × speed of light | 1.98644582e-9 |
erg nm |
au |
Astronomical unit | 1.49597871e13 |
cm |
r_sun |
Solar radius | 6.957e10 |
cm |
r_jup |
Jupiter equatorial radius | 7.1492e9 |
cm |
ag0 |
Asymmetry factor (radiative transfer) | 0 |
— |
Gas constant \(R\)
The universal gas constant is \(R = k_B \times N_\text{avo}\), and the specific gas constant for a species with molar mass \(M\) is \(R_\text{spec} = R / M\).
hc is used to convert the stellar flux to actinic flux (photons cm\(^{-2}\) s\(^{-1}\) nm\(^{-1}\)).