i6 



NATURE 



[Feb. 8, 1877 



The star on that day, when the sky cleared up lor a few 

 hours, was of magnitude, 4-5 ; it appears then to have 

 decreased considerably in brightness, for Schmidt esti- 

 mated the star on November 24, at magnitude 3. The 

 colour of the star is not remarkable — yellowish-red ; the 

 spectrum is one of the most interesting that I know. It 

 is the coloured band crossed by numerous (from eight to 

 ten) dark bands, and besides there are several bright 

 lines visible. 



I have prepared an accurate drawing of the spectrum, 

 which exactly agrees with a drawing made shortly before 

 by Dr. Lohse. At the very first sight the spectrum of the 

 new star appeared to me entirely different from those of 

 the reddest stars, and a later accurate comparison with 

 the drawing has enabled me to discover no satisfactory 

 connection either with the so frequently met with band 

 spectrum lll.a, or with the rare class lll.b (Secchi's 

 type, III. and IV. respectively). Of the bright lines there 

 was one specially conspicuous in the farthest red, as also 

 one on the boundary of the green and blue, and two lines 

 in the blue. In the yellow and green appeared some very 

 bright stripes (.'' bands), which I, however, cannot con- 

 sider proper bright lines (of which the specimen of glow- 

 ing gas consists), but of which I believe there are places 

 in the spectrum, which, by contrast with the neighbouring 

 dark absorption bands, stand out conspicuously. In the 

 case of the very marked band spectra of Class 111.^, one 

 has very often, and especially with a disturbed sky, the 

 impression that there are bright lines in the spectrum, 

 while with favourable atmospheric conditions, it is clearly 

 perceived that regions of the spectrum deficient in lines in 

 the neighbourhood of dark bands produce that impres- 

 sion. 



The observations were made by means of a small spec- 

 troscope formerly described by me. With a larger Brown- 

 ing instrument some measurements were later attempted, 

 and one of the bright lines undoubtedly recognised as the 

 second hydrogen line F. The lines in the blue gave the 

 wave-lengths 474 and 470 mill. m.m. Bright places in 

 the spectrum (very possibly bright lines) were further 

 observed with 512 and 498 mill. m.m. wave-lengths. We 

 did not manage to measure the red lines. 



In further characterising the spectrum, I might state 

 that the blue and violet, in comparison with other stars 

 which showed a band spectrum, was very well seen, and 

 that, at all events, in consequence of the proportionally 

 small general absorption which this part of the spectrum 

 undergoes, the colour of the star differs little from the 

 mean star colour. 



On December 8 I succeeded in confirming and com- 

 pleting the observations herewith sent. I estimated the 

 star at magnitude 5 — perhaps it was even less. By means 

 of the small spectroscope several measurements were ob- 

 tained of bright lines and stripes ( .'' bands) of the spec- 

 trum ; especially was it possible to observe very accurately 

 the position of the red lines, and to identify them with 

 the red hydrogen line C. The following further measure- 

 ments were made : — 



Wave-lengths. 



587-589 



469-470 



526-528 (E)l 



513-514 



507-509 



497-499 



485 -486(F) 



Bright lines. 



Bright stripes, very possibly bright lines. 



Bright line. 



The state of the atmosphere was bad, and very often 

 the observations were interrupted by clouds for a long 

 time. The double numbers for the wave-length should 

 indicate the limits within which the particular line lies 

 according to the measurements. It is hereby evident 

 that besides the hydrogen lines C and F the line D.j 

 (wave-length 487-5) appears bright in the spectrum oif 

 the star. The magnesium line (6^ I have not been able 



to see bright, but I have repeatedly measured a bright 

 stripe, somewhat more broken than 6, which very possibly 

 is identical with a bright line which, under special circum- 

 stances, stands out as the brightest line in the spectrum 

 of the hydrocarbons. A line appeared to me to shine out 

 temporarily in the violet, apparently the third hydrogen 

 line in the neighbourhood of G. 



I hope to be able, ere the star becomes too weak for 

 spectroscopic research, to obtain some more accurate 

 measurements in the positions of the bright lines. 



I may in conclusion add the remark that in the con- 

 stellation Cygnus there are three stars,^ whose spectra 

 are without parallel ; we have therefore, in a tolerably 

 circumscribed space of the sky, including Schmidt's new 

 star, four objects which give a spectrum entirely differing 

 from the many hundred stars examined hitherto. 



H. VOGEL 



Since the receipt of the first account of Dr. Schmidt's 

 Nova the weather here has generally been of the most 

 unfavourable character, and it was not until January 2 

 that the new star could be examined with the 15-inch 

 refractor of this observatory. On the evening of that day 

 the Nova was of about the seventh magnitude and of a 

 decided red colour. The spectrum, as shown in a spec- 

 troscope of Dr. Vogel's construction, was of surprising 

 brilliancy, and consisted of a faint continuous spectrum 

 interrupted by five bright lines. The positions of these 

 lines determined in parts of the scale of the instrument, 

 and afterwards reduced to wave-lengths by comparing 

 the spectra of moonlight and various elements are as 

 follows : — 



Mill. m.m. 

 No. I W. L. 655 Intense bright red. 



2 581 Middle of a rather bright band in the 



yellow, fading off rapidly on both sides. 



3 504 Bright, well-defined line. 



4 486 ,, „ ,, 



5 456 Faint line in the violet. 



It is remarkable that four of these wave-lengths agree 

 closely with those of bright lines previously observed. 

 Nos. I and 4 are obviously the C and F lines of the 

 hydrogen spectrum. No. 3 coincides almost exactly with 

 the brightest line of gaseous' nebulce, and lastly, No. 2 

 corresponds very nearly with one of the bright lines in 

 the spectra of the three remarkable stars in the Swan, 

 pointed out by Messrs. Wolf and Rayet, and subsequently 

 observed by Dr. Vogel (see Berichte d. K'dnigl. Slicks. 

 Ges. der Wiss. Math. Phys. CI., 1873, p. 556 fif.). As yet 

 it has been impossible to confirm the above results, but 

 considering the great interest of the subject I venture to 

 lay this imperfect account before the readers of the Astro- 

 noinische Nachrichten. Ralph Copeland 



Lord Lindsay's Observatory, Dunecht, January 8 



Yesterday night I observed the star of M. Schmidt ; 

 it was about the seventh or eighth magnitude, of a colour 

 tending to greenish, but yellower than on the preceding 

 day. The spectrum is formed of two strong lines, of 

 which one corresponds to hydrogen and the other to mag- 

 nesium. The sodium was still more marked and bright. 

 There was besides another line in the violet, probably also 

 hydrogen. The red of this gas is very weak and does not 

 bear measurement. Besides these four very beautiful lines 

 there were a number of small lines between D and the 

 magnesium, but the space where are the two bright lines 

 of magnesium and the F and the H is almost devoid 

 of light. After these two bright hnes towards the violet 

 there is a dark gap, and then follows a group of very fine 

 lines. So that the description given by M. Cornu is cor- 

 rect : only the bright lines are not bordered by nebulosity, 

 but are as perfectly defined as the bright lines of nebulas. 



Rome, January 9 P. A. Secchi 



• B.D. No. 4001, 40013 -f 35° ; 3956 -f 36° ; by Wolf and Rayet disco- 

 vered, by me accurately examined. Communicated to the K. Scick 

 Geselhch. der Wiss., December 12, 1S73. 



