DISPATCH
constants.py
1 #
2 """
3  Useful physical constants with units given in the comments.
4 """
5 
6 # radiation and atomic physics:
7 clight = 2.99792e10 # speed of light [cm s**-1]
8 SBc = 5.670373e-5 # Stefan-Boltzmann constant [erg s**-1 cm**-2 K**-4]
9 arad = 4.0 * SBc / clight # radiation constant [erg cm**-3 K**-4]
10 kBoltz = 1.3807e-16 # Boltzmann's constant [erg/K]
11 mpro = 1.6726e-24 # proton mass [g]
12 mamu = 1.66054e-24 # atomic mass unit [g]
13 hPlanck = 6.6260755e-27 # Planck's constant [erg s]
14 
15 # astronomical:
16 au = 1.49598e13 # astronomical unit [cm]
17 m_sun = 1.98892e33 # mass of the Sun [g]
18 r_sun = 6.9598e10 # radius of the Sun [cm]
19 l_sun = 3.839e33 # luminosity of the Sun [erg s**-1]
20 gcnst = 6.67e-8 # gravitational constant [cm**3 g**-1 s**-2]
21 pc = 3.0856776e18 # parsec [cm]
22 m_earth = 5.972e27 # mass of the Earth [g]
23 r_earth = 6.371e8 # radius of the Earth [cm]
24 
25 # conversion factors:
26 eV_to_K = 1.1604505e9 # electron volts to Kelvin
27 Habing = 1.6e-3 # CGS units of flux [erg cm**-3 s**-1] to Habing units
28 yr_to_s = 3.156e7 # years to seconds