620 Tables 792-795 



SPECTROSCOPIC DATA 



(Mostly derived by permission from Russell, Dugan, and Stewart, Astronomy, 



Ginn & Co., 1917.) 



TABLE 792. — Percentage of Stars of Various Spectrum Classes 

 (Henry Draper Catalogue) 



Visual B A 

 magnitude (HotoBs) (B8toA3) 



Brighter than 2.24... 28 28 



2.25 to 3.24 25 19 



3.25 to 4.24 16 22 



4.25 to 5.24 9 2,-7 



5.25 to 6.24 5 38 



6.25 to 7-24 4 30 



7.25 to 8.24 2 26 



8.25 to 9.24 1 27 



Below 9.25 1 S3 



All together 2 29 



Among 6000 brighter than 6.25 m only 20 are recorded at Harvard as Class O, 8 of N. 

 The brightest stars of Class O are 7 Velorum (2.22 m) and ? Puppis (2.27 m) ; of Class N, 

 19 Piscium (5.30 m) ; only about 70 of Class R and 20 of S known. Brightest R, 

 — I0°5057, (7.04 m) ; S, 2 Gruis (6.65 m). 



TABLE 793. — Galactic Concentration of Various Spectrum Classes 

 (Henry Draper Catalogue) 



Above 7.0 mag. B 



40 to Q0° 0.2 



0° 10.8 



7.0 to 8.25 mag. 



40 to 90° O.I 



o° 18.9 



Star density per 100 sq. degrees. O stars entirely confined to Milky Way. N stars also 

 strong galactic concentration. 



TABLE 794. — Distribution of Binaries as to Spectrum Class 



Brighter 8.75 mag. No. 



All stars 98675 



Visual pairs 3939 



Eclipsing pairs 132 



Visual orbits no 



TABLE 795. — Masses of Spectroscopic Binaries. Sun 



Class 08 



No. of stars 1 



Inferior limit il/isin 3 i ... 75 

 " " .l/isin^i. . . 63 

 Ratio 84 



Note. — 16 Urs. Maj., spec, binary, F8 dwarf, RA 9" 6", dec. + 61 ° 51', annual p. m. 

 0.032", M + 4, 7r 0.06, rad. veloc. — 15.0 km/sec. in about io° yrs will pass within 2 parsecs 

 of sun. Barnard's star and a Centauri are only two stars known closer than 2 parsecs. 

 They will pass the sun distant 1.1 and 0.93 parsecs. Kapteyn's star was distant 1.6 parsecs 

 10,000 years ago; 279 Sagittarii, 1.4 parsecs, 35>ooo years hence. (Pop. Astron. 32, 

 324, 1924.) 



Smithsonian Tables 



