Smithsonian Report, 1941. — Adams 



PLATE 2 



AVg> 4000 



CONTINUOUS 



INTER- 



STELLAR 



HYDROGEN 



COMBINED 



Ca H H Na 



EARTH 



Diagram Showing the Origin of the Continuous Spectrum and Various 

 Types of absorption lines in Stellar Spectra. 



i 



2. Stellar Spectra Showing Absorption lines Due to Interstellar Gases. 



a, 55 Cygni. H and K lines due to interstellar ionized calcium, and diffuse lines due to stellar elements. 



b, f Ophiuchi. Interstellar lines \ 4232, unidentified, and X 4300, hydrocarbon cas (CH). 



c. ^O nhiuchi. Interstellar lines of CH, X 3886 and X 3890; also X 3874.6 and a trace of X 3874.0, both cyanogen 

 (ON). 



