Astro Constants

Constants and Units

Physical Constants

Name Symbol Number Units
Speed of light c 2.99792458 1010 cm/s
Planck constant h 6.6260755(40) 10-27 erg.s
Reduced Planck constant 1.05457266(63) 10-27 erg.s
Gravitational constant G 6.67259(85) 10-8 cm3/g/s2
Electron charge e 4.8032068(14) 10-10 esu
Mass of electron me 9.1093897(54) 10-28 g
Mass of proton mp 1.6726231(10) 10-24 g
Mass of neutron mn 1.6749286(10) 10-24 g
Mass of hydrogen mH 1.6733 10-24 g
Atomic mass unit amu 1.6605402(10) 10-24 g
Avogadro’s number NA 6.0221367(36) 1023 mol-1
Boltzmann constant kB 1.380658(12) 10-16 erg/K
Electron Volt eV 1.6021772(50) 10-12 erg
Radiation density constant a 7.5646 10-15 erg/cm3/K4
Stefan-Boltzmann constant σ 5.67051(19) 10-5 erg/cm2/K4/s1
Fine structure constant α 7.29735308(33) 10-3
Rydberg constant R 2.1798741(13) 10-11 erg

Astronomical Units

Name Symbol Number Units
Astronomical Unit AU 1.496 1013 cm
Parsec pc 3.086 1018 cm
Light Year ly 9.463 1017 cm
Solar Mass M 1.99 1033 g
Solar Radius R 6.96 1010 cm
Solar Luminosity L 3.9 1033 erg/s
Eff. Solar Temperature Teff 5.780 103 K

CGS to SI

From To Multiply By
CGS SI  
cm m 10-2
g kg 10-3
erg J 10-7
dyn N 10-5