Evening star., 1938-07-07
OF STARS
MEN AND ATOMS
Notebook of Science PROGRESS
in Field, Laboratory
and Study.
By THOMAS r. HENRY.

Finding of the third star making up
the unique triad Of Algol, the Demon.
was reported before astronomers OF the
American Association for the Advance
ment of Science meeting in Ottawa
last week by DR.. j. A. Pearce OF the
Dominion Observatory at Victoria.
British Columbia.
Algol, the one bright star in the con-
stellation Of Perseus which is how creep
ing over the horizon in the Northern
United States and Canada about 10 pm.
has constituted one of the outstanding
mysteries of astronomy for q thousand
wears. Arabian astronomers named 1t
"the demon" because of its inexplicable
behavior. 1t is fairly bright star which
maintains a constant brightness for 56
hours. Then, in short space of six
and a half hours, 1t declines to one
fourth of its normal luminescense. AL
most Immediately it starts to brighten
again, regaining its normal status in
another six and half hours. 1t has
about the same regular brightness as
the North Star.
Astronomers began to fathom the
secret of the demon star when the fact
that many celestial bodies which seem
to be single stars actually are double
stars revolving around their common
center of gravity. Although the men,
bers of such pair may be millions OF
miles apart, their distance from the
earth is so great that they appear as a
single body even when viewed through
the most powerful telescope.
One Of the stars of the Algol COM
bination, it was determined, was about
four times brighter than the other.
Every Sc hours the dim star passed
between the bright star and the earth,
causing the remarkable light diminu-
ton. From evidence gathered with the
spectroscope it was determined that the
system was revolving at the rate of about
rs miles q second and that 1t was ad-
vancing toward the earth at a speed Of
a little more than two miles a second.
But even with this explanation some
Of the queer behavior of Algol remained
unexplained. Mathematical considera-
tions led astronomers to the theory that
there was still third star moving about
the common center Of gravity, consti-
tuting a combination which. so far as
known, is unique in the heavens.
The third star remained a theory,
however, until the announcement of
DR.. Pearce yesterday that by means of
improved spectrographic apparatus he
has been able for the first time not only
to prove the existence, but actually to
obtain the spectrum Of the mysterious
celestial body.
Analysis Of the lines Of this spectrum,
it is expected, will reveal the direction
Of motion and the speed Of the so-called
Algol c and will show what 1t Is made Of.
Northern Hemisphere stars moving
five times as fast as the sun in SEEM
ingly aimless race around the center
Of the universe were reported by DR..
r. K. Young, director Of the astronomi-
cal observatory Of the University Of
Toronto.
He told Of measuring the proper mo-
tions Of 500 faint stars in selected areas
OF the heavens north Of the celestial
equator, bringing to a total Of nearly
5000 the number of heavenly bodies
whose speeds and directions are now
known. Some, he said show speeds Of
more than 60 miles q second. Earth
with its nine planets is relatively q
laggard, with steady pace Of only about
II miles q second.
The investigations reported are part
Of long time program to determine
more accurately the mechanics Of the
celestial system Of about 10000 .000, 900
stars which are circling forever. but ap-
parently in two opposite directions,
around some central point located near
the constellation Of sagittarius, the
hunter.
Generally the more massive the stars
the slower they appear to be moving.
DR.. Young said in explaining his report,
but there are 50 many exceptions to
this rule that some other factor, as yet
unknown, must be operating. The
speed Of star is determined quite ac-
curately by shifts in the lines Of its light
spectrum which can be photographed
with telescope. From this it is nee
essary to subtract the speed Of the sun
itself, which seems to be moving in q
straight line at right angles to the CEN
ter of the universe toward a point mid
way between the consultations of Her
cules and Lyra, both Of which now are
almost directly above in the midnight
sky.
The problem Of the universes star
swarming is only very generally UNDER
stood at present, DR.. Young said.