June 13, 1918] 



NATURE 



285 



HUE NEW STAR IN AQUILA. 



THE unremitting- character of the watch kept 

 on the sky by the amateur astronomers in. this 

 country is well shown by the number of indepen- 

 dent discoveries of the new star. Apparently, the 

 first observation was made by Miss Grace Cook 

 at Stowmarket when on the watch for meteors at 

 9.h, 30m. G.M.T. on June 8. Other independent | 

 discoveries were made by Mr. W. F. Denning, at , 

 Bristol, and Mr. David Packer, at Birmingham, at ' 

 lo.o G.M.T. ; Mr. C. L. Brook, at Meltham, at 

 10.15 G.M.T.; Mr. W. H. Steavenson, at West 

 "Norwood, at 10.30 G.M.T. ; Mr. H. Thomson, at 

 Newcastle, at 10.44 ^- ^- T., and Mr. Felix de 

 Roy, at Thornton Heath, at 10.45 G. M. T. It was 

 ; also noticed at 9.40 G. M. T. by Mr. Witchell, of 

 the Royal Observatory, Greenwich, but" not identi- 

 fied as a Nova. On the following day it was also 

 detected independently in Scotland by Dr. Ander- 

 son, the discoverer of Nova Persei and Nova 

 1 Aurig-ae. Mr. Denning says that the increase in the 

 I light of the star must have occurred during day- 

 time in England on June 8, for he was observing 

 meteors nearly the whole of the preceding 

 night and saw nothing unusual in the sky. Pre- 

 sumably, therefore, the object must have been faint 

 at the time and, in any case, of such small magni- 

 tude as to enable it to escape detection. As yet 

 little information has been received with regard 

 to observations in other countries ; the star was 

 seen at the Hector Observatory in New Zealand, 

 but apparently i2h. after its discovery in England. 

 At discovery the star was very nearly of the 

 same brightness as Altair (ogm.). The testimony 

 of all the discoverers agrees on this point. It 

 was confirmed by photometric observations at 

 Greenwich by Mr. Jonckheere, who determined 

 the magnitude with a wedge photometer by com- 

 parison with Vega, Arcturus, and x\ltair. The 

 change of brightness in the short night of June 

 8 was very slight, if indeed perceptible. In colour 

 the star was like a Aquilae. With the highest 

 power the star showed a sharply-defined stellar 

 nucleus in the 28-inch telescope at Greenwich. So 

 far as could be seen with an eye-piece prism, the 

 L spectrum appeared to be perfectly continuous, no 

 [ night lines being detected. At the Cape Observa- 

 tory the important observation has been made that 

 the Nova contains hydrogen and calcium absorp- 

 tion lines similar to Nova Persei, February 22, 1901, 

 It is not stated in the cablegram whether the 

 observation was made on June 8 or June 9. 



A great increase of brightness occurred in the 

 next twenty-four hours. On Sunday night the 

 star certainly equalled Vega (oim.) in brightness, 

 though Vega was at a much greater altitude. 

 Observation at Greenwich was somewhat difficult 

 (iwing to some faint, low-lying haze. To some 

 observers the star appeared to be considerably 

 brighter than Vega. As on the previous night no 

 l:)right lines were seen in the star's spectrum. 



The position of the star relative to B.D. 

 + 0*4023° (8'5m.) was determined by M, Jonck- 

 heere. Using the position of this star given in 



NO. 2537, VOL. lOl] 



the Abbadia Catalogue (1900) the position of the 



Nova is found to be 



R.A. i8h. 44m. 43v||8s., Dec. 0° 29' 282'' for i9i8*o 



Direct observation at the Transit-Circle by Mr. 

 Witchell gave 

 R.A. i8h. 44m.-43'47s., Dec. 0^29' 31 5'' for i9i8'o 



It was noticed by M. Jonckheere that a star on 

 the Algiers Chart Zone +1°, No. 141, having the 

 co-ordinates - 3' and - 32' and of the ninth magni- 

 tude seemed to be in the position of the Nova. 

 Reference to the measures of the Algiers Astro- 

 graphic Catalogue shows that this star is No. 108 

 on plate 1003. Its, magnitude is given as 8'8m. Its 

 co-ordinates on this plate (centre : i8h. 40m. and 

 0°) are +570074' and +27-8588'. With the data 

 given in the catalogue the position of the star is 

 found to be 

 R.A. i8h. 44m.,43'52s., Dec. o°29'3i'o'/ for i9i8'o 



It thus seems very probable that the Nova is 

 identical with this star of the Algiers Astrographic 

 Chart and Catalogue, photographed on the dates 

 Aug. 20, 1909 and June 26, 1895. This star is 

 also shown on a Franklin Adams plate taken at 

 Johannesburg in 1910. It cannot be said with 

 certainty that these three photographs show no 

 evidence of variability, though on the photographs 

 of 1909 and 1910 the star is perceptibly fainter 

 than the neighbouring star (No. 105 in the Algiers 

 Catalogue) while in the catalogue (date of photo- 

 graph, 1895) it is given as of the same magnitude 

 (8-8m.). If the identity of the Nova with this star 

 is confirmed the point is one of great interest. 



It is fortunate that the Nova will be well placed 

 for observation for some months, so that; ample 

 records of its varying luminosity and spectrum will 

 probably be secured. At the present time the star 

 rises practically due East at about-7.20 p.m., and 

 is on the meridian, 39° above the horizon at 

 London, at about 1.20 a.m., G.M.T. 



F. W. Dyson. 



The spectrum of the Nova was observed by 

 me on June 10 with a McClean star spectro- 

 scope on a 3-inch refrajctor, and on June ii with 

 a ZoUner spectroscope on the 6-inch refractor at 

 the Imperial College. It was not notably different 

 on the two evenings, except that the continuous 

 background was possibly more intense on June 

 10. In each case the spectrum' strongly recalled 

 those of Nova Aurigae and Nova Persei in their 

 early stages, shortly after maximum brightness. 

 The most striking feature of the spectrum was 

 the red line of hydrogen, which was of extra- 

 ordinary brilliancy. In the green there was a 

 group of four bright lines, of which the most re- 

 frangible and brightest was doubtless H^, while 

 the others may well have been the enhanced lines 

 of iron about wave-lengths 517, 502, and 492, 

 which were observed in previous novae. Another 

 conspicuous line in the blue was probably Hy. 

 There was also a broad nebulous line about 

 \ 532, and another of the same character which 

 was roughly estimated to be about \ 560. On the 

 red side of the latter was a dark shading, and there 



