Useful Constants

Physical Constants

Gravitational constant G = 6.672(4)*10^-8 cm^3 g^-1 sec^-2
Velocity of light (vacuum) c = 2.99792458*10^10 cm s^-1 (by definition !)
Planck's constant h = 6.62618(4)*10^-27 erg s
hbar = 1.054589(6)*10^-27 erg s
Boltzmann's constant k_B = 1.038066(4)*10^-16 erg K^{-1}
Electron charge e = 4.80324(1)*10^-10 esu
e = 1.602189(5)*10^-19 Coulomb
Proton mass m_p = 1.6726949(9)*10^-24 g
Electron mass m_e = 9.10953(5)*10^-28 g
Stefan-Boltzmann constant sigma = pi^2 k_B^4/(60 hbar^3 c^2)
sigma = 5.6703(7)*10^-5 erg s^-1 cm^-2 K^-4
Thomson cross section sigma_T = 8 pi e^4/(3 m_e^2 c^4)
sigma_T = 6.65245(6)*10^-25 cm^2

Astronomical Constants

Astronomical Unit 1 AU = 1.49597892(1)*10^13 cm
Light-Year 1 ly = 9.4608953536(1)*10^17 cm
Parsec 1 pc = 648,000/pi AU (by definition)
1 pc = 3.08567802(2)*10^18 cm
1 pc = 3.26150740(2) ly
(Siderial) Year (1900) 1 yr = 3.1558149984*10^7 s
Solar Mass M_sun = 1.989(2)*10^33 g
G * M_sun = 1.32712497(1)*10^26 cm^3 s^-2
Solar radius R_sun = 6.9599(7)*10^10 cm
Bolometric Solar Luminosity L_sun = 3.826(8)*10^33 erg s^-1
Escape velocity from Sun v_* = 617.5 km s^-1
Absolute Solar Magnitude M_v = +4.83
M_B = +5.48
Earth Mass M_earth = 5.976(4)=10^27 g
Hubble constant H0 = 60..75 km s^-1 Mpc^-1
H0 = 18..23 km s^-1 Mly^-1
H0 = 1.9..2.4 *10^-18 s^-1
Hubble Time H0^-1 = 4.1..5.2*10^17 s
H0^-1 = 13.0..16.3*10^9 yr

Values in parentheses give inacuracy in preceding digit.

Useful approximate relations:

        1 km/s ~ 1 pc per million y               (1.023)
        M_sun/L_sun ~ 0.5 in cgs units            (0.52)
        1 radian = 206,265" ,  1 pc = 206,265 AU  (648,000/pi)

References


[SEDS]

Hartmut Frommert [contact]