NATURE 



[May 4, 1893 



Surely it is not too much to assume the existence of 

 meteoritic swarms of such comparatively small 

 dimensions. 



In some incidental remarks upon temporary stars, Mr. 

 Maunder agreed with Mr. Lockyer in iZ()o {Journal of 

 the British Astronomical Association, vol. i. No. i, p. 29) 

 that they " must be stars in quite another sense to our 

 sun. The rapidity with which their brightness diminishes 

 is plain proof of this. Only small bodies could cool so 

 rapidly, and since despite their vast distance (for their 

 parallax is insensible) these Novas show themselves con- 

 spicuous, we are obliged to explain their brilliancy by 

 considering them as consisting of aggregations of such 

 small bodies ; the total extent and mass of the swarm 

 making up for the insignificant size of its components." 



It will be seen that Mr. Lockyer's theory fits in with 

 these observations most aptly. " New stars," he says 

 (Roy. Soc. Proc, vol. xliii. p. 154), "whether seen in con- 

 nection with nebulas or not, are produced by the clash of 

 meteor swarms. Clearly, as the swarm cooled down 

 after the collision, we should find its spectrum tend to 

 assume the nebular type." It is quite immaterial whether 

 the chief nebular line is considered to be due to magne- 

 sium or not. According to the meteoritic hypothesis, a 

 new star, as it diminishes in brilliancy, and presumably 

 in temperature, must degrade towards the condition of a 

 nebula. Accept the observations in proof of such a 

 transformation, and the idea that nebute are entirely 

 composed of glowing gas becomes untenable, unless it is 

 believed that a Nova increases in temperature as it dimin- 

 ishes in brightness. On the other hand, the change of a 

 new star into a nebula gives strong support to Mr. 

 Lockyer's view that nebulae are low temperature phe- 

 nomena. In a paper " On the Causes which Produce the 

 Phenomena of New Stars"(Phil. Trans., vol. clxxxii.(i89i) 

 A. pp. 397-448) Mr. Lockyer shows that the spectroscopic 

 observations of Nova Coronas, Nova Cygni, and Nova 

 Andromedae are in agreement with his hypothesis. It 

 was therefore expected that Nova Aurigae should 

 assume the characteristic badge of a nebula. The ex- 

 pectation has been strikingly realised. In August, 1892, 

 the star revived, and on the 19th of that month Prof. 

 Campbell, of the Lick Observatory, wrote the following 

 account of his observations of it {Astr. Nach., No. 3133): — 

 "The brightest line previously observed was resolved 

 into three lines, whose wave-lengths were about 501,496, 

 and 486, which were at once recognised to be the three 

 characteristic nebular lines. The same morning Prof. 

 Barnard, using the 36-inch equatorial, observed the Nova 

 as a nebula 3" in diameter, with a tenth magnitude star 

 in its centre. Thus the nebulous character of the object 

 was independently established by two entirely different 

 methods." Writing on the same subject. Prof. Barnard 

 remarks {Astr. Nach., No. 3143): — "I think it unques- 

 tionable that had any decided nebulosity existed about 

 the star at its first appearance, it would have been detected 

 in observations with the 36-inch, especially when the star 

 had faded somewhat. So it is clearly evident that there 

 has been an actual transformation in every sense of the 

 word of a star into a nebula within an interval of only 

 four months." Herr Renz has also observed the nebular 

 character of the Nova by means of the Pulkowa refractor. 

 On the other hand, one or two observers have been unable 

 to detect the nebulosity, and it does not appear on Dr. 

 Roberts's photograph of the region. It is impossible, how- 

 ever, to think that an observer of Prof. Barnard's calibre 

 could have been deceived in the matter ; hence the con- 

 flicting observations are probably accounted for by 

 fluctuations in the extent and brightness of the nebulosity. 

 The fact that Dr. Max Wolf's photographs of the Nova 

 fail to show any haziness round the star goes for nothing, 

 for a patch 3" in diameter could not be distinguished 

 from a point upon the scale of his pictures. 



The spectroscopic evidence of the nebular character 



NO. 1227, VOL. 48] 



of Nova Aurigas in its old age does not rest merely upon 

 Prof Campbell's observations. Prof. Copeland examined 

 the spectrum on August 25 and 26, and also Mr. J. G. 

 Lohse. From the measures obtained the mean values 

 assigned to the two brightest lines were X 5003 and 

 X 495'3, while a fainter line was seen in the position 

 X 5801, which is also the position of a bright line found 

 in the Wolf-Rayet stars and Nova Cygni (Nature 

 vol. xlvi. p. 464). Mr. Fowler has also observed the 

 two lines at 5006 and 4956 {Ibid. vol. xlvii. p. 399). But 

 perhaps the most convincing of all testimonies is con- 

 tained in a paper by Herr Gothard on the spectrum of 

 the new star in Auriga as compared with the spectra of 

 planetary nebulae (Monthly Notices R.A.S., vol. liii. p. 55). 

 The author has photographed the spectra of a number of 

 nebulae, and compared the results with his _ photographs 

 of the Nova spectrum. " Each new photograph," says he, 

 " increased the probability, which may be considered as 

 a proved fact that the spectrum not only resembles, but 

 that the aspect and the position of the lines show it to be 

 identical with the spectra of the planetary nebulce. In 

 other words the new star has changed into a planetary 

 nebula." In the face of this array of facts nothing could 

 appear to be more satisfactorily established than the 

 descent of the Nova to the condition of a nebula. Up 

 to the present only one observer. Dr. Huggins, has de- 

 livered himself of a contrary conviction. His observa- 

 tions have led him to believe that " the bright band in 

 the Nova spectrumis resolved into a long group of lines ex- 

 tending through about fifteen tenth-metres" when a high 

 dispersion is employed {Astr. Nach., No. 3153). This 

 observation, however, has not been confirmed, hence it 

 cannot be " implicitly accepted." It can hardly be dis- 

 cussed until Dr. Huggins gives a more explicit descrip- 

 tion of the number and positions of the individual lines 

 he has seen. 



Such are the theories with regard to the origin 

 of Nova Aurigae and new stars generally. From the 

 survey we see that Huggins' theory of burning worlds 

 suggested to account for the appearance of a new star 

 has gone the way of Tycho Brahe's idea that such 

 bodies are new creations. Any and all chromospheric 

 theories fail to explain the transformation of the 

 Nova into a nebula, so they should be abandoned. And 

 finally, the whole sequence of spectroscopic phenomena 

 is explainable on the hypothesis that the light was pro- 

 duced "by the clash of meteor-swarms." From the 

 point of view of the meteoritic hypothesis things could 

 hardly have turned out more satisfactorily than they 

 have, yet at least one carping critic, after being forced 

 to admit the testimony of his eyes that the Nova now 

 exists as a nebula, has ventured to say that the fact 

 tells against it. How, forsooth ? Simply to make such 

 a statement without backing it up reminds one very 

 forcibly of mud-thrOwing. Let the blows to the hypo- 

 thesis be fairly given, and as fairly met, for only by 

 such means can the truth prevail. 



Richard A. Gregory. 



THE ROYAL SOCIETY SELECTED 

 CANDIDATES. 



THE following fifteen candidates were selected on 

 Thursday last (April 27) by the council of the 

 Royal Society, to be recommended for election into the 

 Society. The ballot will take place on June i at 4 p.m 

 We print with the name of each candidate the statement 

 of his qualifications. 



William Burnside, M.A., 



Professor of Mathematics at the Royal Naval Collejre, Green 

 wich. Formerly Fellow of Pembroke College, Cambridge 

 Author of the following papers among others:— "On Deep 



