Evening star. [volume] (Washington, D.C.) 1854-1972, 1905-09-30


ably similar to enormous cyclones In the
Vaporized and intensely hot body Of the sun.
ninth magnitude telescope star Il sud
denly blazes out at irregular intervals of
ABOUT eleven months, becoming one OF the
conspicuous stars of the sky This re-
markable periodic change in this great sun
mas been thus observed for four centuries
and as yet it shows sign of relaxation
Another celebrated variable is the Demon
star, Algol, which will be found at D.
Fig. 1. This instead of growing brighter
VIII at perfectly definite interval of two
Gays twenty-one hours lose more than a
whole magnitude of five-sixths of its light
remaining thus faint for about twenty min
utes and in about three and one-haIf hours
regaining its original brightness 1t is now
known that this darkening is caused by n
second star which Is revolving about Algol.
ana winch passes between US and this star
at every revolution Altogether seventeen
stars which vary in this way have been
discovered. One of the most striking OF
them is at L. Fig. 1. This diminshes one
whole magnitude in brightness every three
days twenty-three hours
The observer will find Algol at its faint
est on October 1, a. m; October 4, l a.
m, and October @. 8 D. m The star /,
is at its falntest October g. 1 pm and at
intervals of three days twenty-three hours
after this.
In third type of variable stars the
brightness will gradually increase then fall
away a little, and finally increase again
much more than before, after which IT
VIII die out until the star is as faint as
before any increase began. The time that
elapses between the successive outbreaks Is
apt to be very variable
The star at e Gig. u, is one of these
III Is at Its fainteSt October /, II D. m and
october 10, 10 p. m, and at its brightest
october 0, II a. m, and October IS. 4
"a m. The star at T Gig. u is faintest
October ?, a. m, and October o, noon;
1t is brightest October 4, D. m and DC
tober IL, IL p. m The star at X is faint
est October 6. a. M. and October IL,
noon. and at its brightest October Z, noon
lose about one whole magnitude of five
sixths of their light in changing from max
imum to minimum brightness.
1t Is certain that inconceivably violent
disturbances are occurring In these great
suns to cause such changes in their light
1t may be that each variable star is com
posed of two suns, formed of incandescent
SaporlZed matter, and that in each revo-
luton these suns Craze even partially
lnterpenetrate each other. shown in Fig.
2. Or the second star may only pass near
the first, in which case its attraction would
distort both stars into demonstrated fig
ures and thus set up violent oscillations in
them which might account for the increase
of light observed.
1t may be, on the contrary, that a va
riable star is but one sun which has sun
spots on II just our sun has but very
much larger ones, and the irregular in
crease and diminution of the number and
size of these spots may be the cause OF
the changes observed. Indeed, our own
sun is slightly variable star whose
brightness is at a minimum every eleven
years, when the spots are most numerous
Its spots are so small, however that the
variation of its light is very slight The
explanation of what Is actually going on
in these remote suns to cause the enormous
changes observed remains yet to be discov-
cred.