Tables 825-827 



TABLE 825. — The Cepheid Period-Luminosity Curve 



635 



Shapley, Harvard Bull., 861, 1928. 



Shapley, Harvard Monogr., 2, 1930. 



TABLE 826.— Novae 



Novae (temporary stars) : Between 10 to 20 brighter than the 9th app. mag. occur in a 

 year (Bailey). Numerous in spiral nebulae. More than 80 in Andromeda nebula 

 (Hubble) ; 30 per year estimated. Mean parallax of five, 0.01" ; abs. mag. + 8.5 to — 3.1 

 (Russell). Nova Aquilae, 1918, class A before outbreak; then appears as rapidly expand- 

 ing gas 1700 to 2300 km/sec; fades to Wolf-Rayet, class O (T Coronae Bor. changed 

 finally to gM) ; gaseous envelope visible 1918 to 1926, reached diameter 16"; abs. mag. 

 + 3 to — 8.8; distant 1200 light years. Nova Persei : Diffuse cloud faint light expanding 

 6' to 7' in 7 months. Six weeks later moved 35" to 65" — apparently due to illumination of 

 dark nebulous matter near star by outgoing light (Russell). See Milne, Nature, 128, 715, 

 1 93 1. If after outburst it has dwindled to previous magnitude but spectrum shows a 

 higher temperature, then radius must have decreased, say 10-fold, and the density would 

 be much greater (compare white dwarfs, Table 828), 



TABLE 827. — Observed Maxima of Spectrum Lines in the Giant Sequence 



(Shapley.) 



* Data for the supergiant sequence. 

 Smithsonian Tables 



