168 SOME RECENT ASTRONOMICAL EVENTS. 



Popular Astronomy, November, 1901, shows the histoiy of the bright- 

 ness of the stur up to the last of April. 



Immediately after its discover}^ the spectrum of Nova Persei was 

 thoroughh' studied both by photography and visual obserA^ations. 

 When first found its spectrum was almost perfectly continuous, but a 

 close examination revealed a few delicate dark Fraunhofer lines in 

 the green, so that at that time the spectrum was, though feebly devel- 

 oped, yet of the so-called Orion type, and very unlike that of the other 

 new stars which had heretofore been observed, and of which bright 

 lines are the most conspicuous feature. By Februar}^ 24 the spectrmn 

 showed a remarkable change, being now traversed by numerous dark 

 and bright bands and closely resembling that of the famous Nova 

 AurigtB (an earlier discovery of Dr. Anderson), so that the star now 

 became entirely similar to other new stars. This type of spectrum 

 continued with onl}" moderate variations until March 19, when there 

 appears to have been a peculiar change in the spectrum. No dark 

 lines were present on that date except a few faint lines due to the par- 

 tial reversal of the bright bands, but the continuous spectrum was 

 almost invisible. On March 23, however, the continuous spectrum had 

 reappeared with narrow dark lines, and on ]March 27 and afterwards 

 there was a strong continuous spectrum. During the month of April 

 the spectrum departed from the recognized type in many particulars, 

 and occasionalh" the continuous part was absent, only separated bright 

 bands remaining. There appears then to have been two tj^pes of spec- 

 trum during the months of March, April, and May, while the bright- 

 ness of the star was so variable, and it is interesting to note that on 

 the dates when the spectrum was peculiar — that is to say, not similar 

 to the spectra of the other new stars— the brightness of Nova Persei 

 was at a minimum. 



But not only has Nova Persei made a characteristic record for itself 

 as regards the variations of its brightness and of its spectrum, but in 

 August it presented a new and still more remarkable feature. Reports 

 came from France that a faint nebula had been photographed about 

 the star, and while this was at first contradicted and ascribed to optical 

 defects in the apparatus, yet it was not long before the discovery was 

 thoroughl}^ confirmed, and a faint circular nebula was photographed 

 surrounding the planet like a halo. IS[or was this all, for there were 

 in the nebula several condensations of nebulosity, which were suffi- 

 ciently marked to have definite positions. 



On November 7 and 8 this nebula was photographed at the Lick 

 ObservatorA", and upon comparing the position of the condensations of 

 which I have spoken with the photograph obtained on Septeml)er 20, 

 at the Yerkes Observatory, it was found that these condensations had 

 actually moved at a rate which, if continued for a year, would amount 

 to 11 minutes of arc in the heavens. The reader will find evidence 



