On the Chemistry of the Hottest Stars. 



177 



Bellatrix, 

 /3 Persei, 



7 Ly ra3 > 



Sirius, 

 Castor, 

 Procyon, 

 Arctnrus. 



Map V indicates the variations of the metallic lines in this series of 

 stars, and it will be seen that at the highest temperature magnesium 

 and calcium are represented by their enhanced lines alone ; with a 

 fall of temperature the enhanced lines of iron are next added, and, 

 later, the arc lines of all three metals ; at the lowest temperature, 

 the enhanced line of magnesium disappears, while those of iron are 

 ■either absent or very weak ; the enhanced lines of calcium, on the 

 other hand, being relatively strong in the arc, remain. 



BELLATRIX 



T T ' t 



. ft PERSEI 



Li , t 



* ■ y LYR£ 





1 1 . 1 Llit, 1 l_ 



1 T 1,1 1 1 



SIRIUS 



Iff 



1 ! ! II 11 1 II 



ii 1 1 



CASTOR 







ll fl i ll ' 



> id 





PROCYON 













1 





\ ML l l 



ARCTURUS 



) 

















! . ' 



ENHANCED 



LINES 









i 



> 1 



i 







' CHARACTERISTIC 

 j ARC LINES 



" 1 



! II 





! 



58 



39 40 41 42 AZ 4 4 4-5 



46 



Map V.— Behaviour of metallic lines in stars of decreasing temperature. 



