Astrophysical Formulae

This book is meant to be a reference source for the fundamental formulae of astrophysics. Wherever possible, the original source of the material being pre- sented is referenced, together with references to more recent modifications and applications. More accessible reprints and translations of the early papers are also referenced. In this way the reader is provided with the often ignored his- torical context together with an orientation to the more recent literature. Any omission of a reference is, of course, not meant to reflect on the quality of its contents. In order to present a wide variety of concepts in one volume, a concise style is used and derivations are presented for only the simpler formulae. Ex- tensive derivations and explanatory comments may be found in the original references or in the books listed in the selected bibliography which follows. Following the convention in astrophysics, the C. g. S. (centimeter-gram-second) system of units is used unless otherwise noted. To conserve space, the funda- mental constants are not always defined, and unless otherwise noted the fol- lowing symbols have the following meaning and value. Symbol Meaning Value 10 c Speed of light in vacuum 2. 997924562(11) x 10 cm S-l h=2nh Planck's constant 6. 626196(50) x 10 - 27 erg s Rationalized Planck's constant 1. 0545919(80) x 10- 27 erg s h=h/2n k Boltzmann's constant 1. 380622(59) x 10 - 16 erg K - 1 4.