640 



Tables 837-839 

 TABLE 837. — Diffuse Galactic Nebulae, Dimensions 



(Trumpler, Proc. Astron. Soc. Pacific 43. 255, 1931-) 



TABLE 838. — Nongalactic Nebulae 



(Hubble, Astrophys. Journ., 64, 1926.) 



Some 400 considered. Distribution of magnitudes appears uniform throughout sequence. 

 For each stage in the sequence the total magnitude (Mr) is related to the max. diameter 

 (d) by the formula: Mr = C-5 log d. When minor diameter is used, C approx. constant 

 throughout sequence (C = 10. 1). Mean absolute visual magnitude —15.2. The statistical 

 expression for distance in parsecs is log D = 4.04 + 0.2 M T . Masses appear to be of the 

 order of 2.6 X io 8 X our sun's. Apparently nebulae as far as measured are distributed 

 uniformly in space, one to io 17 parsecs 3 or 1.5 X io~ 31 in C.G.S. units. 



Corresponding radius of curvature of the finite universe of general relativity is of order 

 of 2.7 X io 10 parsecs, about 600 times the distance at which normal nebulae can be detected 

 with the Mt. Wilson 100-inch reflector. 



TABLE 839. — The Magellanic Clouds and N.G.C. 6822, Dimensions 



(Hubble, Astrophys. Journ., 62, 409, 1925.) 



* Harvard Coll. Obs. Circ. no. 268. t loo cit. 255. t loo cit. 260. § Harvard Coll. Obs. Bull. no. 816. 

 Smithsonian Tables 



