INDEX OF SUBJECTS 
The numbers refer to the pages 
a Aquilae (Altair), 7, 53 
a Aurigae (Capella), 41, Plate VI (p. 49), 57, 59 
a Bootis (Arcturus), 41, Plate VI (p. 49), 56, 59 
a Canis Maj. (Sirius), 5, 7, 31, 33, 41, Plate VI 
(p. 49), 58, 59, 129, 130, 182 
a Canis Min. (Procyon), 7, 33, 41, Plate VI 
(p. 49), 63, 182 
a Centauri, 5, 7, 8, 23, 24, 31, 33, 59, 129, 130, 
298 
a Cygni (Deneb), 41, 53 
a Lyrae (Vega), 8, 31, 41 
a Orionis (Betelgeux), 41, Plate VI (p. 49), 56, 
59, 129 
a Scorpii (Antares), 56, 59 
a Tauri (Aldebaran), 41, 53 
a Ursae Min. (Polaris), 41, 53, 313, 382 
Absorption-lines in stellar spectra, 48, 49 
Absorption of radiation, 83 
Adiabatic equilibrium, 61, 92, 258 
Age of the earth, 396, 409 
,, universe, 139, 381, 421 
Ages of the stars, 129, 130, 139, 185, 316 ff., 
376, 380, 381, 417 
Albert (asteroid), 4 
Aldebaran, 41, 53 
Altair, 7, 53 
Andromeda, nebula M 31 in, Plates I (p. 15), 
VII (p. 331), VIII (p. 332), 15, 
18, 19, 333, 352 
Angstrom unit (A), 39 
Annihil ation of matter, 113, 127, 135, 139, 418 
Antares, 56, 59 
Arcturus, 41, Plate VI (p. 49), 56, 59 
Asteroids, 3 
Atomic diameters, 48, 412 
,, numbers and atomic weight of stellar 
matter, 102, 103, 108, 112, 134, 
161, 167, 380, 419 
,, structure, 412 
|3 Cephei, 382, 390 
(3 Lyrae, 288, 289 
|3 Orionis (Eigel), 41, 53 
B-type stars, system of, 375 
Belt of Orion, 3, 24 
Betelgeux, 41, Plate VI (p. 49), 56, 59, 91, 129 
Bifurcation, points of, 189 
Binary stars, 20, 225, 288, 310, 323 
,, ,, eccentricities and periods of, 21, 
289, 290, 291, 295, 301, 305, 
306, 307 
„ „ mass-ratio in, 326 
,, ,, number of, 22 
,, ,, planes of orbits of, 379 
,, „ spectroscopic, 20, 288, 290, 310, 
325, 326, 327 
,, ,, visual, 20, 178, 291, 310 
Birth of stars, 328, 350, 380 
Bolometric correction, 43, 45, 46 
,, magnitude, 42, 48 
Braking action of radiation, 274 
Calcium clouds, 28 
Capella, 41, Plate VI (p. 49), 57, 59, 180 
Cepheid parallaxes, 10, 18, 25 
,, variables, 11, 12, 23, 382, 387, 388, 
391, 394 
Chemical elements, 51 
„ ,, in solar spectrum, 51 
,, ,, in stars, 133, 134 
Clusters (globular), 12, Plate III (p. 25), 25, 
26, 372, 377 
„ (moving), 24, 26, 372, 375, 379, 417 
,, (open), 26 
Collisions of stars, 319 
Colour-index, 42, 43, 45, 54 
Companion of Sirius (Sirius B ), 33, 58, 59, 132, 
182 
Condensations in spiral nebulae, 345, 379, 416 
Contraction-theory of stellar energy, 110, 122 
Convection currents, 69, 92, 93 
8 Cephei, 11, 383, 387 
Decrease of stellar mass, 114, 131, 298, 417 
“Degeneracy” of stellar gas, 74 
Deneb, 41, 53 
Density of star distribution in space, 8,12,15, 
17, 368 
Density distribution inside a star, 91, 282 
Distances, stellar, 1, 5, 9 
,, nebular, 18, 341 
Dwarf stars, 61 
Dwarfs (white), 63,132, 143, 160, 165,180, 181, 
182, 184, 185, 419