APRIL 4, 1912] 
NATURE 
IzI 
OUR ASTRONOMICAL COLUMN. 
Tue SPECTRUM AND Orpir or 8 Scorpu.—In No. 14, 
vol ii., of the publications of the Allegheny Observa- 
tory, Drs. Daniel and Schlesinger discuss the measures 
of seventy-three spectrum plates of 8 Scorpii and 
deduce an orbit. They confirm Dr. Slipher’s state- 
ment that the H and K calcium lines do not share 
in the large oscillations shown by the other lines. As 
in 6 Orionis and o Persei, the velocity shown by 
‘these lines is approximately the velocity of the centre 
of mass of the system, thus indicating that the absorb- 
ing material producing the lines is really part of the 
system. Other notable features are the great eccen- 
tricity of the orbit, excessive for a star of the B type 
with so short a period, and the comparatively large 
masses of the components. 
Tne Axis aNnp Compression oF Mars.—Including 
observations up to 1909, Dr. Struve has determined 
the axis of Mars, from the shifts of the orbital planes 
of the satellites, which confirm similar values found 
by him in 1896. He finds the obliquity of the planet’s 
equator to the orbit to be 25° 102’, a value which, as 
Dr. Crommelin points out in the current number of 
The Observatory, is about the mean of previous deter- 
minations from observations of the snowcaps; 
Herschel gave 28°, while Prof. Lowell’s latest value 
was 23°. The compression of the planet is given as 
1/190°4, and the mass as 1/3,090,000, the same as 
formerly adopted. The daily angular motion of 
Phobos is 1128°844°, and of Deimos 285°162°. 
OBSERVATIONS OF NOVA GEMINORUM 
NOW 2: 
ANY observations of the nova, of which we give 
a selection below, are reported in No. 4563 of 
the Astronomische Nachrichten. The observations of 
magnitude are not very accordant, but they indicate 
that the nova was probably discovered before it 
reached its greatest brightness. 
Prof. Wolf reports that there was a star brighter 
than magnitude 12’0 in the position of the nova on 
March 7, while two Harvard photographs showing 
eleventh-magnitude stars do not show the nova on 
March 10; but two plates taken on March 11 show 
it as a fifth-magnitude star. A plate taken by Dr. 
Kopff in 1909 shows the image of a fifteenth-magni- 
tude star which is probably identical with the nova. 
Some of the magnitude estimations are given in the 
following table :— 
Date 
| G.M.T- Magnitude System Observer 
| h. m. 
March 13| 7°45 4°1 Harvard Revised | Stroémgren 
14| 10 30 3°6 — Wirtz 
15| 6 30 4°18 P.D. Guthnick 
15} 9 30 4°31 ’ Freundlich 
15] 11 42 4°5 Se Guthnick 
167 15 5°42 Harvard Revised Felix de Roy 
17| 8 49 537) Pa: Graff 
20| 7 29 5°34 » 
20/ IT 49 5°51 ” Fn 
24; — 4°6+ — Nijland 
24; — 50+ — Easton 
265 = oe = 
27; — 65 = Easton ; 
a Nijland 
In communicating the last four values, Dr. C. 
Easton directs attention to the oscillations of bright- 
ness indicated by the recrudescence observed on March 
NO. 2214, VOL. 89| 
24, when he observed at Amsterdam and Prof. Nijland 
at Utrecht; both observers were hampered by clouds 
and moonlight. 
M. de Roy estimated the colour to be orange- 
yellow, 5°5 c. on Osthoff’s scale, as seen in an 8-in. 
reflector, and Dr. Hartwig gives it as reddish. 
Prof. Wolf states that the spectrum on March 15 
was similar to that of Nova Aurigze, but on March 17 
it was more like that of Nova Lacerte during the 
period January 6-14, 1911. On March 14 Herren 
Struve, Guthnick, and Freundlich saw broad absorp- 
tion lines at Ha and H§&, and the last-named suspected 
bright condensations in several places; a bright line 
in the yellow is given as probably D or D,. Prof. 
Hertzsprung saw the H and K absorption lines doubled 
on March 15, the one part being very narrow and in 
its normal position, the other being about 7 A.U. 
broad, and, in the mean, displaced by an amount 
corresponding to —650 kms. per sec. A large number 
of fine absorption lines similar to those in a spectrum 
of F type were also seen. Prof. Schwarzschild states 
that the observations made with the Potsdam spectro- 
graph, No. 1, on March 15, showed a number of 
absorption lines about 1 A.U. in breadth. Among 
these are well-defined lines of the spark spectrum of 
titanium, indicating by their displacements a radial 
velocity, referred to the sun, of —540 kms. per sec. 
On March 17 the displacements of these lines indi- 
cated a motion of —350 kms. per sec. in the line of 
sight. Observations on March 17, 18, and 19 indi- 
cated that the continuous spectrum was becoming 
weaker relatively to the bright bands. 
Some interesting spectroscopic results secured by 
M.M. Hamy and Millochau at the Paris Observatory 
are published in No. 13 of the Comptes rendus (March 
25). Two spectrographs were employed, one with a 
slit giving a spectrum 40 mm. long from Hé8 to K, 
the other an ultra-violet prismatic camera giving the 
same length of spectrum between A500 and A300. On 
the plates secured with the latter the continuous 
spectrum is seen easily to extend to 4315, a fact which 
is accepted as showing the extremely high tempera- 
ture of the light-source. 
A large proportion of the total radiation from the 
star is shown to be concentrated in the bright hydrogen 
lines, which are about 20 A.U. in width, and become 
more and more diffuse towards the violet end of the 
spectrum. H6 is divided into three equal parts and a 
similar division is suspected in Hy; Hd, He, H¢, and 
H@ are also shown. These broad, bright hydrogen 
lines are strongly displaced towards the red by an 
amount equivalent in HS, Hy, and He to 3 A.U., 
and each is accompanied by a broad absorption band 
on the more refrangible side; the dark hydrogen bands 
are, as usual, considerably displaced, and have fine, 
bright reversals running down their centres. The 
displacements are equivalent to those that would be 
produced by a radial velocity of the order of —1300 
kms. per sec. in the atmosphere of hydrogen, which 
produces the double reversals. The authors, however, 
attribute the broadening and the displacement of the 
lines to the enormous pressures which might be pro- 
duced in the cataclysm following the impact of a star 
and a nebula, such as was outlined in Seeliger’s 
theory. 
Many apparently bright lines occur between A470 
and A390, but the authors are not sure that these are 
not merely the interspaces between feeble absorption 
bands; they do, however, affirm the existence of a fine 
absorption band at A394. Between A370 and A315, only 
continuous spectrum is seen, and the spectrum as a 
whole is similar to those of Nove Aurigze (1892), 
Persei (1901), and Geminorum (1903). 
