1866,] 



Spectrum of a New Star in Corona Borealis. 



147 



that this nebulosity really existed about the star. When the spectroscope 

 was placed on the telescope, the light of this new star formed a spectrum 

 unlike that of any celestial body which we have hitherto examined. The 

 light of the star is compound, and has emanated from two different sources. 

 Each light forms its own spectrum. In the instrument these spectra appear 

 superposed. The principal spectrum is analogous to that of the sun, and is 

 evidently formed by the light of an incandescent solid or liquid photosphere, 

 which has suffered absorption by the vapours of an envelope cooler than 

 itself. The second spectrum consists of a few bright lines, which indicate 

 that the light by which it is formed was emitted by matter in the state of 

 luminous gas *. These spectra are represented with considerable approxi- 

 mative accuracy in a diagram which accompanies this paper. 



Spectrum of Absorption and Spectrum of Bright Lines forming the Compound 

 Spectrum of a New Star near e Coronas Borealis. 



Description of the spectrum of absorption. — In the red a little more 

 refrangible than Fraunhofer's C are two strong dark lines. The interval 

 between these and a line a little less refrangible than D is shaded by a num- 

 ber of fine lines very near each other. A less strongly marked line is seen 

 about the place of solar D. Between D and a portion of the spectrum 

 about the place of b of the solar spectrum, the lines of absorption are 

 numerous, but very thin and faint. A little beyond b commences a series 

 of close groups of strong lines ; these follow each other at small intervals, as 

 far as the spectrum can be traced. 



Description of the gaseous spectrum. — A bright line, much more bril- 

 liant than the part of the continuous spectrum upon which it falls, occupies 

 a position which several measures make to be coincident with Fraun- 

 hofer's Ff. At rather more than one-fourth of the distance which 



* The position of the groups of dark lines shows that the light of the photosphere, 

 after passing through the absorbent atmosphere, is yellow. The light, however, of the 

 green and blue bright lines makes up to some extent for the green and blue rays (of 

 other refrangibilities) which have been stopped by absorption. To the eye, therefore, 

 the star appears nearly white. However, as the star flickers, there may be noticed an 

 occasional preponderance of yellow or blue. Mr. Baxendell, without knowing the re- 

 sults of prismatic analysis, describes the impression he received to be " as if the yellow 

 of the star were seen through an overlying film of a blue tint." 



t On the 17th, the lines of hydrogen, produced by taking the induction -spark through 

 the vapour of water, were compared in the instrument simultaneously with the bright 

 ines of the star. The brightest line coincided with the middle of the expanded line of 

 hydrogen which corresponds to Fraunhofer's F. On account of the faintness of the red 



VOL. XV. O 



