TABLE 874.— GIANT AND DWARF STARS (concluded) 763 



Typical supergiants, giants, and main-sequence stars 



TABLE 875.— TEMPERATURE IN INTERSTELLAR SPACE* 287 



Because interstellar matter is far from being in thermodynamic equilibrium, the tempera- 

 ture of space will depend on the measuring process used. 



Temperature from energy density of starlight 3°K 



Color temperature of starlight 10,000 — 15,000°K 



dilution factor 10" u 



Temperature of gas (kinetic) 



H I region (hydrogen neutral) 60° K 



H II region (hydrogen ionized) 10,000°K 



Temperature of grains (internal energy) 20°K 



* Prepared bv B. Donn, Harvard University. 



287 Dunham, Proc. Amer. Philos. Soc, vol. 81, p. 277, 1939; Eddington, Proc. Roy. Soc. London, 

 vol. A 111, p. 424, 1926; Spitzer, Astrophys. Journ., vol. 107, p. 6, 1948; vol. 109, p. 337, 1949; vol. Ill, 

 p. 593, 1950; van de Hulst, Rech. Astron. Obs. Utrecht, vol. 11, pt. 1, 1946. 



SMITHSONIAN PHYSICAL TABLES 



