406 INDEX
Persico, E., 280
Perturbation of electron orbits, 71
Pettit, E., 206
Photometric orbits, 148, 209
Photosphere, 334, 360
Planck’s constant, 46, 395
Planck’s law, 21, 49, 53, 55
Planetary nebulae, 389
Plaskett, H. H., 330, 342
Plaskett, J. S., 148, 156, 214, 378
Plummer, H. C., 185
Point-source of energy, solution for, 124
Polytropic gas-sphere, 80; tables, 82; in
complete, 94; applicable to stars, 117, 128
Potential, gravitational, 79; at centre of
star, 83, 85
Potential energy of polytrope, 86 ; of a star,
141
Poynting vector, 57
Pressure, 79; at centre of a star, 85, 91; in
reversing layer, 349; in photosphere, 360;
electrostatic correction to, 266, 269;
broadening of lines by, 353
Pressure of radiation, 15; theory of, 27;
numerical value, 38; ratio to whole pres
sure, formulae, 117, 129; tables, 117, 137;
determines stellar masses, 16, 118, 308;
stress components of, 105, 335; in outer
layers, 357, 360; in chromosphere, 362;
escape of atoms by, 368
Principal lines, 74, 346, 349, 363
Procyon, 152; companion, 155
Protons, destruction of, 293
Pseudo-Cepheids, 181
Pulsation, of Cepheids, 180; criticisms, 185;
adiabatic theory of, 186; period of, 192;
limit to amplitude, 194; maintenance of,
200; of long period variables, 206
V Puppis, 147
Quanta, 41, 46; general conception of, 57
Quantisation, of hydrogen-like ion, 58; of
molecules, 352; lack of sharpness, 60, 354
Quantum numbers, 59, 70, 72
Quartic equation, fundamental, 117, 129
Radiation, 27; equilibrium of, 35; tempera
ture of, 37; Stefan’s law, 38; Wien’s law,
39; Planck’s law, 55; flow of, 101, 322;
from accelerated electron, 77, 223; pene
trating, 317
Radiation of stars (total), 114; relation to
opacity, 118; relation to mass and radius,
134; relation to luminosity, 138. See also
Luminosity, Absolute magnitude, Mass-
luminosity relation
Radiation pressure. See Pressure of radia
tion
Radiative equilibrium, 9, 97; equation of,
101, 107, 322
Radiative viscosity, 281
Radio-activity, 294, 315, 344
Radiometer, 138
Radius, of Cepheids, 182; of long period
variable, 208; of sun, 395
Radius of star, 2; interferometer measures,
6; method of calculating, 13; method for
Algol, 210
Rayleigh scattering, 384, 385
Reflection effect in eclipsing variables, 210,
213
Refractive index, 38, 237
Relativity, 6, 173
Reversible processes, 32
Reversing layer, 342; pressure in, 349, 359
Rigour of proofs, 102
Ring nebula, 389
Ritter, A., 5
Rosseland, S., 109, 238, 243, 264, 401
Rosseland’s correction, 112, 247, 356, 398
Rotating stars, brightness of, 287; currents
in, 285; von Zeipel’s theorem, 282
Rotation, of Algol, 210; of planetary nebulae,
389
Runaway electrons, 302, 320
Russell, H. N., 7, 148, 160, 163, 177, 295,
303, 354
Rutherford, E., 220
Saha, M. N., 345, 347
Sampson, R. A., 9
Scattering by electrons, 74, 243, 384; co
efficient of, 76
Schuster, A., 400
Schwarzschild, K., 9, 322, 342
Seares, F. H., 174
Selection principle, 71, 73, 351
Series in spectra, 74
Shajn, G., 160, 311
Shapley, H„ 8, 146, 181, 310, 342, 384
Shielding of nuclear field by electrons, 67, 71,
264
Shinjo, S., 203
Silicon, spectra of, 345
Sirius, companion of, 171
Size of atoms and ions, 165, 262, 359
Smart, W. M., 312
Sodium, fixed lines of, 378, 383
Sorting demon, 37
Source of stellar energy, 289; relative dis
tribution of, 122, 295; point-source, 124
Space, interstellar, 371 ; temperature in, 371,
377; density in, 372, 382; ionisation in,
383; absorption of light in, 383; pene
trating radiation from, 318
Specific heats, ratio of, 9, 35; for radia
tion, 10, 29; for stellar material, 270; in
Cepheids, 157, 190, 203; limit of stability,
142
Spectra, X-ray, 70, 230, 234; optical, 72;
molecular, 350. See also Absorption.
Emission, Spectral type
Spectral energy curve, 324