DOUBLY IONIZED NITROGEN
The lines of doubly ionized nitrogen were singled out by Lockyer[218] as showing “abnormal behavior”—they do not appear in the same classes as the N+ line. The early work on the subject is discussed by Baxandall.[219] The most conspicuous lines are those at 4097, 4103, and they attain great intensity in the
stars;[220] they are, for example, very conspicuous in 29 Canis Majoris. H. H. Plaskett[221] places the maximum of the N++ lines in the Victoria class
. They are last seen in some
stars.
The occurrence and behavior of the N+ and more especially the N++ lines in the Nova spectrum has been the subject of numerous investigations.[222][223][224][225][226][227]
OXYGEN (8)