Relation between the Spectra of Swnspots and Stars. 53 



" On the Eelation between the Spectra of Sunspots and Stars." 

 By Sir NOKMAX LOCKYEK, K.C.B., LL.D., F.E.S. Eeceived 

 June 8,Eead June 16, 1904. 



As the period throughout which the observations of widened lines 

 have been made at South Kensington now includes two maxima and 

 three minima epochs of solar activity, it has seemed desirable to 

 discuss the results obtained, taking in DO account the chemical origins 

 of the lines affected in passing from the photosphere to the sunspot 

 nuclei. This is going on, but in anticipation of its publication, I 

 desire to direct attention to one of the conclusions arrived at in its 

 bearing upon the question of the temperature conditions of the 

 Arcturian and lower type stars, which formed part of the subject of 

 a recent paper. * 



Since 1894, when the last discussion of the widened line results 

 was published,! nearly 10,500 observations of lines in sunspot spectra 

 have been made at South Kensington. An analysis of these lines, 

 in respect to their origins, shows that the elements chiefly affected during 

 the period 1892 1903, inclusive, were Vanadium and Titanium. 



The great importance of Vanadium and Titanium in sunspot spectra 

 has also been demonstrated by Father Cortie during his observations 

 in the B D region at Stony hurst. | 



It was foreshadowed in a previous paper on the chemical classifica- 

 tion of the stars that it seemed probable that, as the result of further 

 work, the " genera " then proposed might have to be split up into 

 " species." During the more recent research mentioned above the 

 temperature classification was tested by comparing the relative 

 intensities of the red and ultra-violet ends of the spectra of stars, 

 situated on various horizons of the temperature curve, including 

 Capella and Arcturus, which, according to the original general 

 classification, belong to the same type, viz., " Arcturian." It was 

 found that the spectrum of Capella extended on an average about 

 70 tenth-metres further into the ultra-violet than that of Arcturus, 

 whilst the red portion of the spectrum is certainly stronger in the 

 latter. That is to say, the general temperature of Arcturus is probably 

 appreciably lower than that of Capella. 



The next step was to see if chemical change accompanied this 

 reduction of temperature, and if so, whether the change was in any 

 way related to the change from the photosphere to the sunspot 

 spectrum. 



* ' Koy. Soc. Proc.,' vol. 73, pp. 227238, 1904. 



f ' Roy. Soc. Proc.,' vol. 57, p. 199, 1894. 



I ' Monthly Notices (K.A.S.),' vol. 63, No. 8, pp. 479480, June, 1903. 



' Roy. Soc. Proc.,' vol. 65, p. 191, 1899. 



