Light For Short Periods Research Articles

THE NEW STAR IN PERSEUS.—Sir Norman Lockyer recently communicated to the Royal Society some further observations of the new star in Perseus made at the Solar Physics Observatory in continuation of the last previously recorded (Roy. Soc. Proc, vol. Ixviii. p. 399). In the present paper, which brings the information up to the end of September, it is first pointed out that the short period light variations have ceased and that the Nova was gradually becoming fainter, reaching about magnitude 6·7. In the visual spectrum the nebular line at wave-length 5007 was the strongest. Photographs of the spectrum showed that since last April a great change has taken place. The lines then were very broad and ill defined, but are now much narrower with better defined edges. The lines of hydrogen, which were the strongest in the spectrum have become comparatively very weak. Other lines have made their appearance, the strongest of which are 3868 and 3970, 4364 and 4720. The first is an unknown line strong in the spectra of planetary nebulæ, while the other three are of unknown origin. It is suggested that the second line (3970λ) is not the line of hydrogen at He, as the other hydrogen lines in the spectrum are so weak. There is, further, a new line in the ultra-violet at wave-length 342 (about), which Gothard has independently recorded. It is interesting to note that the new gas lines show a structure somewhat similar to that of the hydrogen lines in earlier photographs. The enhanced lines of iron, magnesium, &c., which were such a conspicuous feature of the first photographs, have entirely disappeared, and. the probability is that the bright lines now, other than hydrogen and helium, belong to gases the terrestrial equivalents of which have not been found.

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