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 | ℏ | 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 |