April 25, 1913] 



SCIENCE 



643 



2 are peculiar in an increased intensity of X 4363. 

 A broad bright band approximately at X 4363 was 

 the strongest band in the spectrum of Nova Gemi- 

 norum, No. 2, on November 9, 1912, and may be 

 characteristic of the spectra of new stars when 

 they become gaseous, as it is also very bright in 

 the photographs of Nova Arje and Nova Velorum. 



A second class of the spectra of gaseous nebulse 

 has a line in the violet, which is probably a blend 

 of X STSG' and X 3729, for the strongest line, while 

 X 3S69 and X 4686 are absent, and the chief nebular 

 lines X 4959 and X 5007 are barely visible. No. 

 418 of the Index Catalogue, DM. — 12M172, is 

 the only object so far found belonging to this 

 class. Since X 3727 and X 5007 are both present 

 in the spectrum of the Great Nebula of Orion, it 

 may be intermediate between the two classes 

 represented by N.G.C. 7662 and I.C. 418. A third 

 division of gaseous nebulae has X 4686 for its 

 strongest line. N.G.C. 40 is typical of this class, 

 and one other a = 19''0"".5, S = — 6°8' (1900), 

 simUar to it, has been found. This class of nebula 

 is of special interest, owing to a possible connec- 

 tion with the spectra of Class O, in which a bright 

 band at the same approximate wave-length is the 

 distinguishing feature. When an object is faint, 

 it may show only the bright band 4686, and it 

 would then be impossible to determine, from its 

 photographic spectrum, whether it belonged to 

 Class O or to the third division of gaseous nebulae. 

 N.G.C. 40 was observed by Herschel, and a pho- 

 tographic chart plate shows its nebulous character. 



For the purpose of comparison a composite pho- 

 tograph was exhibited showing the spectra of 

 Sirius, of I.C. 418, N.G.C. 7662, Nova Geminorum 

 II., on November 9, 1912, the same on March 13, 

 1912, H.E. 2583 typical of Class 06 and N.G.C. 

 40. 

 Stellar Spectroscopic Notes: Walter S. Adams. 



The following notes contain some of the recent 

 results obtained in the course of the regular 

 radial velocity work with the 60-inch reflector. 



The seven stars following are spectroscopic 

 binaries with large range in velocity. ? Arietis, 

 Boss 54s, Mag. 5.6, Spectrum JBj.'^The range 

 shown by the first three plates was 57 km. On a 

 fourth plate two spectra were visible and measures 

 of the separate components gave a relative velocity 

 of 262 km. The spectra of the two stars are 

 nearly identical. Boss 24Si, Mag. 6.2, Spectrum 

 A^. The range shown by three plates 88 km. 

 2 Comw Berenicis, Boss 3150, Mag. 6.2, Spectrum 

 A^, The range shown by three plates 53 km. Boss 



SSJfO, Mag. 6.8, Spectrum A^ peculiar. Range 

 shown by three plates 105 km. 16 SagitarU, Boss 

 .'tGlS, Mag. 6.2, Spectrum B^, peculiar. Range 

 shown by three plates 86 km. Traces of a second 

 spectrum are visible, a Aquilae, Boss 5018, Mag. 

 5.2, Spectrum B^. Two spectra are visible on the 

 first plate, one of the type B5 and the other B,. 

 The relative velocity of the two components on 

 this plate is 367 km. Boss 5070, Mag. 5.8, Spec- 

 trum Bj. Range shown by three plates 138 km. 



Two photographs of the spectrum of the star 

 Lalande 15290, Mag. 8.2, Spectrum G5, show that 

 its radial velocity is the largest of any star ob- 

 served to date in the northern sky. The spectro- 

 grams which were taken in April and November, 

 1912, give values of — 243 and — 241 km., respect- 

 ively. A photograph of this star taken in Decem- 

 ber, 1910, with a temporary spectrograph gave an 

 approximate velocity of — 250 km. Its proper 

 motion is 1".97 annually and its parallax is 0".045 

 according to the values summarized by Kapteyn 

 in Groningen Publications No. 24. Its velocity in 

 space accordingly as referred to the sun is 318 km., 

 a value only slightly inferior to that of 1830 

 Groombridge. 



Observations of a number of the brighter stars 

 in the h and x P^rsei clusters lead to the inter- 

 esting conclusion that most of these stars have 

 nearly the same radial velocity and apparently are 

 moving together. The stars observed are as fol- 

 lows: 



Mean 

 Mag. Spectrum Velocity 



B.D. -4- 57°.494 6.5 A^ —44 



+ 56°.438 6.5 B„ —40 



■4- 56°.470 7.0 B, — 43 



+ 56°.471 6.6 jB, —43 



Boss 519 6.9 B3 — 46 



B.D. + 56°.530 6.9 B. —45 



-4- 56°.568 6.7 A^ —45 



+ 55°.612 6.3 B, —46 



The velocity of Boss 519 is probably variable. 

 The spectra of most of these stars belong to 

 division c of Miss Maury's classification — that is, 

 have relatively sharp lines. The average velocity 

 is exceptionally high for stars of this type and 

 this fact taken in connection with their proper 

 motions and the similarity of their spectra makes 

 it very probable that they form a true group. 

 The star B.D. -4- 55°. 598, Mag. 5.7, has a velocity 

 of . — 18 km. as determined from one plate and 

 should additional photographs show this velocity 

 to be constant it would seem probable that the 



