Back to the article index

Physical Constants

The following table comes from Astrophysical Formulae by Kenneth R. Lang, California Institute of Technology, Pasadena, California and Tufts University, Medford, Massachussetts.

Symbol Meaning Value
c Speed of light in vacuum 2.997924562(11) x 1010 cm sec-1
h = 2 pi hbar Planck's constant 6.626196(50) x 10-27 erg s
hbar = h / 2 pi Rationalized Planck's constant 1.0545919(80) x 10-27 erg s
k Boltzmann's constant 1.380622(59) x 10-16 erg K-1
e Elementary charge of an electron 4.803250(21) x 10-10 ESU
me Rest mass of the electron 9.109558(54) x 10-28 g
G Gravitational constant 6.6732(31) x 10-8 dyne cm2 g-2
NA Avogadro's number 6.022169(40) x 1023 mole-1
a.m.u. = u Atomic mass unit 1.660531(11) x 10-24 g
alpha Fine-structure constant 7.297351(11) x 10-3
e / m Electron charge-to-mass ratio 5.272759(16) x 1017 esu g-1
Rinfinity Rydberg constant 1.09737312(11) x 105 cm-1
a0 Bohr radius 5.2917715(81) x 10-9 cm
h / (mc) Compton wavelength 2.4263096(74) x 10-10 cm
r0 = e2 / (mc2) Classical electron radius 2.817939(13) x 10-13 cm
R Gas constant 8.31434(35) x 107 erg K-1 mole-1
sigma Stefan-Boltzmann constant 5.66961(96) x 10-5 erg cm-2 s-1 K-4
sigmaT Thomson cross section 6.652453(62) x 10-25 cm2
au Astronomical unit 1.49597892(1) x 1013 cm
pc Parsec 3.0856(1) x 1018 cm
ly Light year 9.4605 x 1017 cm = 6.324 x 104 au
Msmsun Solar mass 1.989(2) x 1033 g
Rsmsun Solar radius 6.9598(7) x 1010 cm
Lsmsun Solar luminosity 3.826(8) x 1033 erg sec-1
eV Electron volt
  associated wavelength
  associated wavenumber
  associated frequency
  associated energy
  associated temperature 		1.23963 x 10-4 cm
8.0671 x 103 cm-1
2.41838 x 1014 Hz
1.60184 x 10-12 erg
1.16059 x 104 °K