Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1899-09-16
THE NORTH STAR THREE SUNS

THE NORTH STAR THREE SUNS.
The news from Lick Observatory
that the North Star, 255, 900, 100000 of
miles away from us, has been found to
be not one star, but three-swingiDg
around in great orbits like the moon,
earth and suu-is another remarkable
result Of the application of photo.spec-
troscopy to the telescope study Of the
heavens. Always fascinating, the
search Tor double and multiple stars
has become of the highest interest since
the spectroscOpe has made it possible
to discover multiple stars which the
greatest telescopes do not reveal to the
eye. The three components ofPolarls
cannot DO seen with the most powerful
telescope in the world. But the Lick
star spectrosc0pe, attached TO the
great SO inch refractor, makes it plain
that there are suns revolving about a
sun where the eye distinguishes but
one twiDkling light.
Ten years AGO at the Harvard Uni
versity observatory the first photo
spectroscopic multiple star wGs discov
cred unexpectedly. The star Mizar,
the middle star of the handle Of the Big
Dipper, has been called "naked-eye"
double because it has visible compar-
ion, Alcor, close to it. But Riccoli
10 1850 discovered with the telescope
that Mizar had telescope double. Mi
zar seems to have been the first double
star discovered with telescope. The
apparent distance between Mizar and
Alcor is nearly forty times the distance
that separates the components OF Mizar.
The telescope shows, too, that there are
other stars between Mizsr and Alcor.
Two centuries after the telescope re.
vealed two stars in Mizar the spsctro-
scope showed that the brighter OF the
componepts was itself made up Of two
stars. In photographs taken at the
Harvard Observatory in 1889 the <
line in the spectrum of Mizar appeared
double. In other plates the line was
single, in others it was hazy. A close
scrutiny of all the plates showed that
the line was double at intervals OF fifty
two days. This proved TO astronomers
that the brighter component of Mizar
was really TWO stars. A spectroscope
takes cognizance of the motion OF
a star to or from the earth.
When one star begins to ap'
proach and the other to recede
from Us, the lines in the spectrum OF
the approaching star will be displaced
toward the violet end, while those OF
the receding star will be displaced to-
ward the red end. The lines will at
first appear hszy, but when the ap-
proach and recession of the stars reach
maximum the lines will appear
double. The calculated distance be-
tween the componenis of Mizar is about
143 900, 900 miles, and the brilliancy OF
the star is estimated to be over hun
dred times greater than that of our sun.
A number of other photo.spectro-
scopic multiple stars have been discov-
cred recently. With the Lick telescope
and spectroscope, fourteen have been
found. This method of discovery came
out from the use OF the spectra TO
determine the velocity with which stars
! approached or receded from the earth.
The North Star, it was found short
while ago, is now shooting earthward
at velocity of sixteen miles second.
Two of the suns of the North Star trip
let revolve about each other every
| four days and these two swing about
the third.