INDEX 
Abbot, C. G., 325 
Absolute magnitude, 13; of sun, 14, 149. 
See Luminosity 
Absorption, of radiation, 3, 20, 21, 47, 217; 
of light in space, 384 
Absorption coefficient, for terrestrial X-rays, 
22, 236; relation to emission coefficient, 
50, 54,105; astronomical determination of, 
118, 146; law of variation, 121, 202, 219, 
229, 248; in photosphere, 355; mono 
chromatic, 368 
Absorption edges, 70 
Absorption lines, 238; formation of, 337; 
broadening of, 353; fixed lines, 377 
Abundance of the elements, 369 
Accretion of mass by stars, 391 
Adams, W. S., 2, 160, 171, 172, 307 
Adiabatic changes, 35 ; equilibrium, 97 ; pul 
sations, 186 
Adiabatic principle, 72, 355 
Aetherial heat, 18 
Age, of sun, 289; of earth, 290 
Aitken, R. G., 150, 155 
Albedo of stars, 211 
Algol, 209 
Amplitude of pulsations, 185, 195 
Anderson, J. A., 12, 300 
Annihilation of protons and electrons, 293 
Aston, F. W., 293, 295 
Astronomical constants, values of, 395 
Atom, structure of, 10 
Atomic absorption coefficient, 54, 236 
Atomic numbers of elements, 10, 252 
Balancing, principle of detailed, 45 
Band spectra, 350 
Betelgeuse, 6 
Bialobjesky, I., 397 
Binary hypothesis of Cepheids, 184 
Binary stars, 11, 152, 161; mass ratios of, 
160; change of mass, 311, 312 
Birge, R. T., 350 
Bjerknes, V., 286 
Black body, 39; sun’s deviation from, 325 
Blackness of absorption lines, 340, 342, 347, 
350 
Bohr atom, 60, 72 
Bolometric magnitude, 13; reduction to 
visual magnitude, 138 
Boltzmann’s constant, 51 
Boltzmann’s formula, 49; inapplicable to 
free electrons, 263 
Boundary conditions, 95, 116, 127, 211 
Boundary temperature of stars, 323, 332 
Bright fine spectra, 343 
Broadening of spectral lines, 353; in Ceph 
eids, 206 
Buisson, H., 330 
Calcium, in chromosphere, 362; in inter 
stellar space, 378; ionisation of, 345, 349, 
382 
Cameron, H., 318 
Campbell, W. W., 11, 147 
Canonical variables, 58 
Capella, 11, 14, 85, 145 
Capture of electrons, 23, 218, 221, 230, 245 
TV Cassiopeiae, 214 
Cell of unit weight, 68 
Central temperature of stars, formulae for, 
85, 136; minimum value, 91; numerical 
values, 136, 151, 182; constancy on main 
serips, 177, 299 
8 Cephei, 146, 199, 290 
Cepheid variables, 157, 180, 290 
o Ceti, 206, 208; companion of, 173 
Chapman, S., 277, 279, 280 
Chemical constitution of stars, effect of, 2, 
10, 243; assumptions as to, 250, 370 
Chromosphere, Milne’s theory of, 362 
Circulating currents in rotating stars, 285; 
tendency to die out, 99 
Classical theory, of emission, 223 ; of electron 
scattering, 77 
Classification of spectra, 2 
Cloud, interstellar, 378 
Clusters, masses of stars in, 162; variables in, 
181; giant and dwarf stars in, 310 
Coeval stars, difficulty arising from, 310, 392 
Collisions, inelastic and superelastic, 339, 373 
Companion of Sirius, 171 
Composition. See Chemical constitution 
Compressibility of a gas, 165 
Compton effect, 76, 316 
Condensations in interstellar medium, 381 
Conduction of heat, 97, 281 
Constants, fist of natural, 395 
Contraction hypothesis, 5, 289 
Contrast. See Blackness 
Contrast, centre-limb, 328, 331; in chromo 
sphere, 365 
Convection currents, 98, 285 
Convective equilibrium, 9, 97 
Conversion of subatomic energy, 315 
Correspondence principle, 53,64,230,241,263 
Currents, circulating, 98, 285 
Cyanogen bands, 350 
Dark nebulae, 387 
Darkening at the limb, 212; law of, 324 
Debye and Hückel’s theory, 264, 280 
Decay of pulsations, time of, 199 
Delaunay’s canonical variables, 58 
Dense stars, 130; gas laws in, 165 
Density, of photosphere, 336,360; of chromo 
sphere, 368; of interstellar matter, 372 
382; of nebulae, 382