'''
List of physical, astronomical, and cosmological constants.

'''

# Define pi.
pi = 3.141592653589793
two_pi = 2.0 * pi

#
# Basic constants
#

# Speed of light, in cm/s.
c_cgs = 29979245800.0
c_kms = 299792.458

# Planck constant, in erg s.
h_cgs = 6.6260755e-27
h_bar_cgs = 1.05457266e-27

# Gravitational constant, in cm^3 g^-1 s^-2.
G_cgs = 6.67259e-8

# Electron charge, in esu.
e_cgs = 4.8032068e-10

# Electron mass, in g.
m_e_cgs = 9.1093897e-28

# Proton mass, in g.
m_p_cgs = 1.672623e-24

# Neutron mass, in g.
m_n_cgs = 1.6749286e-24

# Hydrogen mass, in g.
m_H_cgs = 1.6733e-24

# Atomic mass unit, in g.
amu_cgs = 1.6605402e-24

# Boltzmann constant, in erg/K.
k_cgs = 1.38064e-16

# Electron volt, in erg.
eV_cgs = 1.6021772e-12

# Radiation density constant, in erg cm^-3 K^-4.
a_cgs = 7.5646e-15

# Stefan-Boltzmann constant, in erg cm^-2 K^-4.
sigma_sb_cgs = 5.67051e-5

# Fine structure constant.
alpha_cgs = 7.29735308e-3

# Rydberg constant, in erg.
ryd_cgs = 2.1798741e-11
rinf_cgs = 109737.31568538999

#
# Astro units
#

# Astonomical unit, in cm.
AU_cgs = 1.496e13

# Parsec, in cm.
pc_cgs  = 3.08568e18
kpc_cgs = 3.08568e21
Mpc_cgs = 3.08568e24

# Solar mass, in g.
Msun_cgs = 1.99e33

# Solar radius, in cm.
Rsun_cgs = 6.96e10

# Solar luminosity, in erg/s.
Lsun_cgs = 3.9e33

#
# Cosmological constants
#

# Hubble parameter with h = 1, 100 km/s/Mpc, in 1/s.
H0_100_cgs = 3.2407767493712897e-18
H0_100_yr = 1.0220113556817299e-10

# Critical density with h = 1, in g/cm^3.
# rho_crit = 3 H_0^2 / (8 pi G)
rho_crit_100_cgs = 1.8788200386793017e-29
rho_crit_100_Msun_Mpc = 277386144370.4126