THE STARS IN ACTION" JOY 183 



ness in an hour's time. On the following- evening, June 8, having in- 

 creased another hundredfold, it was independently discovered within 

 a few hours after it rose above the eastern horizon by a score of 

 astronomers and amateurs in Europe and America. This remarkable 

 example of the careful watch of the sky which is being maintained 

 at all times leads us to believe that not many bright nova? have 

 escaped observation in recent years. The outburst reached its max- 

 imum on June 10 when the star was equal to Canopus in brightness, 

 being second only to Sirius itself. To know the real time of the 

 outburst about 1,000 years must be subtracted from the date of its 

 a[)pearance, for th(! star is so far away that it takes that time for its 

 light to reach us. 



After its maximum the decline set in, but at a much slower rate 

 than the rise. What was gained in brightness in the 2 days before 

 maximum was lost in 200 days, and af ler that the decline was even 

 slower. It took about 2 years to return to normal intensity after its 

 4 days of dissipation. 



The spectrum showed remarkable changes of a character observed 

 only in novae. At maximum, and presumably before, it resembled 

 the spectrum of a hot, massive star but with the lines greatly dis- 

 placed, indicating that the star was expanding at the terrific rate of 

 over 1,000 miles per second. In spite of this immense expansion to a 

 million times its original volume, the high temperature of over 

 10,000° was maintained so that the surface brightness did not change 

 much until after maximum. The increase in light seems to have been 

 largely the residt of an increase in the dimensions of the star itself. 

 The outbm^st was, in effect, an explosion. 



Soon after maximum a gaseous shell was formed, which has con- 

 tinued to increase in diameter for nine years up to the present time. 

 It now forms a neat ring of gas about the star similar to the ring 

 nebula in Lyra, but about one-fourth its apparent size. Whatever 

 may be the cause of the sudden outburst, we have observed in this 

 ease the actual formation of a ring or planetary nebula in an insig- 

 nificant interval of time, astronomically speaking. A truly amaz- 

 ing phenomenon has taken place before our very eyes. The delib- 

 erate processes of celestial evolution have become a spectacle of ac- 

 tivity and change, speeded up, as it were, so that in the minute 

 span of time loaned to man for his mundane existence he may behold 

 and ponder an example of the splendor of creation. 



As the shell of gas is thrown off from the star at a speed a thou- 

 sand times that of a projectile from a "big Bertha," the character 

 of its radiation changes rapidly. In the emptiness of space, the atoms 

 of the shell are cooled so that they would not be able to radiate at 

 all were it not that the intense ether waves of tlie central star are 

 continually bombarding them from behind and rousing them to 



