The New Star in Hercules

Abstract

THE discovery of this star in the early morning of December 13 by Mr. J. P. M. Prentice at Stowmarket was kindly reported to the Solar Physics Observatory at Cambridge by the Astronomer Royal later in the same morning. Watch has been kept the whole of each night since, the star being circumpolar, and spectra were obtained with the Newall telescope in the early mornings of December 14 and 15. The spectrum is of the usual Nova type, just after maximum brightness, consisting of bright bands of hydrogen and of ionised metals with absorption borders on the side of shorter wave-length. The unusual features on this occasion are the outstanding strength of the displaced absorption lines due to Mg II at 4481 and the fact that the velocity of approach given by the hydrogen and other absorption lines has shown a decrease from about 500 km./sec. to about 250 km./sec. between December 14 and 15. This decrease of the velocity of the first outburst was shown by Nova Geminorum 1912, but it is not a usual feature in Novæ.