THE NEW STAR WHICH FADED INTO STAR-MlST. 135 



and dense flight of meteors upon the central mass the 

 nucleus was roused to a degree of heat far surpassing its 

 ordinary temperature. Thus for a time it glowed as a sun. 

 At the same time the denser central portions of the nebulous 

 matter were also aroused to intenser heat, and the bright 

 lines which ordinarily (and certainly at present) would not 

 stand out bright against the rainbow-tinted background of a 

 stellar spectrum, showed brightly upon the continuous spec- 

 trum of the new star. Then as the rush of meteors upon 

 the nucleus and on the surrounding nebulous matter ceased 

 if that be the true explanation of the orb's accession of 

 lustre or as the cause of the increase of brightness, what- 

 ever that cause may have been, ceased to act, the central 

 orb slowly returned to its usual temperature, the nebulous 

 matter also cooling, the continuous spectrum slowly fading 

 out, the denser parts of the nebulous matter exercising also 

 a selective absorption (explaining the bands seen in the 

 spectrum at this stage) which gradually became a continuous 

 absorption that is, affected the entire spectrum. Those 

 component gases, also, of the nebulous portion which had 

 for a while been excited to sufficient heat to show theit 

 bright lines, cooled until their lines disappeared, and none 

 remained visible except for a while the three usual nebular 

 lines, and latterly (owing to still further cooling) only the 

 single line corresponding to the monochromatic light of the 

 fainter gaseous nebulae. 



