TABLE 851.— STELLAR SPECTRA* 

 Part 1. — The Harvard spectrum classification 



747 



Principal spectral lines 

 Class (absorption unless otherwise stated) 



P Gaseous nebulae. Emission lines and 



bands of H, He I and II, and O II. 



W Wolf-Rayet objects divided into two 



sequences : carbon, WC, have emis- 

 sion lines attributed to He I and II, 

 C II, III, and IV, and O II, III, IV, 

 V, and VI ; nitrogen sequence, WN, 

 have emission lines attributed to He 

 I and II, and N III, IV, and V. 



O Lines of H, He I and II, O II and III, 



and N II and III. 



B Neutral H and He, N II, and O II, 



and a few ionized lines of metals. 



A H series at maximum, Ca II (H and 



K), and weak ionized metallic lines. 



F Ca II (H and K) strong, H lines 



fainter, metallic lines more abundant. 



G H lines faint, Ca II (H and K) strong, 



many fine metallic lines. 



K Ca II (H and K) very strong, many 



neutral metallic lines. Spectrum 

 faint in the violet. 



M Molecular bands of TiO, lines of Ca I 



and II, and other metals. Long-pe- 

 riod variables have emission H lines. 



S ZrO bands and metallic lines. Long- 



period variables have emission H 

 lines. 



R Bands of Ca, CN, and CH ; many me- 



tallic lines. 



N Bands of C 2 , CN, and CH ; very little 



violet light. 



Q Novae. Rapid spectral changes from 



early supergiant type near maxi- 

 mum, through nebular stage, and 

 finally to a Wolf-Rayet type. 



Example 



7 Velorum 



Antares 



r tl Gruis 



BD 



-10°5057 



19 Piscium 



Number 



brighter 



than 



6.2S, 



mag 



457 



Percent 



in 



galactic 



region 



100 



54 



63 

 87 



Part 2. — Prototypes for luminosity classification 



For description of classification of Wolf-Rayet stars see reference, footnote 274. The "galactic 

 region" here means the zone between galactic latitudes ± 30°, and including half the area of the 

 heavens. 96 percent of the stars of known spectra belong to classes A, F, G, K, 99.7 percent 

 including B and M (Innes, 1919). Henry Draper Catalog, 9 vols., 1918-24, and H. D. Extension, 

 2 vols., 1925-49, give positions, magnitudes, and spectra of nearly 360,000 stars. See also Yale 

 Zone Catalogs, and the Bergedorf and Potsdam Spectral-Durchmusterungen. 



* Prepared by M. W. Mayall, Harvard College Observatory. 



273 Trans. Int. Astron. Union, vol. 7, p. 408, 1950. 



274 Trans. Int. Astron. Union, vol. 6, p. 248, 1938. 



SMITHSONIAN PHYSICAL TABLES 



