The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1896-04-08
The Curious Way in Which Astronomers
Discovered Its Size and Relations to
Other Stars.
(Prof. Young in the Youths Companion.

Chair.
But Algol is not like other stars; if
one watches it long and carefully he will
be surprised some evening to find that it
has lost almost quarters of its light.
Once in about SO hours-6S hours 4S
minutes, and SO seconds to be exaot-it
faints away and "comes to-" again, &C.
cupying between 9 and 10 hours in The
whole operation. The star fades for a
little less than five hours, remains I'M
changed for about 20 minutes and
then regains it's former splendor some
what faster than it lost it. The phenom-
enon recurs with perfect regularity, so
that the "fainting fits" can be predicted
almost to the second, and the following
are the times-eastern standard-of
those observations which will occur dur
ing the evening hours of 1896 at times
when our readers can easily observe
them, namely:
Jan. II, 9.a5; Jan. 10 6.45; Jan. 81. 11.o5
Feb. 3, 1855; Feb 23, 9. 80; Feb 26, 6.27
Mar. Il, 11.20; Mar. II, 8. 10;
Sept. %, 7.35; Oct. 10. 9.15;
Nov. z, 10. %; Nov. 10, 7.45; Nov. 80, 9.25
Dec. g. lie; Dec. 90, lilo; Deo %, 100
The changes in the light Of the star
seem TO have been first noticed more than
200 years ago but it was the deaf mute
amateur astronomer, Goodricke of York
in England, who first thoroughly studied
the peculiar behavior of the star, and in
1888 suggested the explanation that has
lately proved true.
The star is now and then partly hidden
or eclipsed by dark object which re-
wolves around it, and comes between 1t
and the earth 1t has q dusky partner,
and the pair waltz swiftly around each
other once in 60 hours. Moreover, from
the way in who the light wanders and
revives again, and the amount by which
it is reduced when the star LIS faintest,
we can learn many things about the size
of the obscuring body, and the dimen-
siOns OF its orbit.
Prof Pickering Of Harvard College,
who, examined the matter very carefully
in 1880, concluded that everything might
be explained by surprising that the dark
star which produces the s'eclipses" has
diameter not quite four-fifths as great
as that of Algol itself, and that in their
motion the two stars keep at an almost
unchanging distance, (which is a little
more than three times the diameter Of
Algol. Both stars move, OF course, the
center of their motion being tie point
between them where their weights would
balance-their common "center of grav-
ity," to use the technical term; and the
circle'on which the larger star moves is
just about half as large as that Travelled
over by the smaller, because the bright
star weighs little more than twice as
| much as the other.
But this is not all. As Prof. Picker
laft fn
determine the real size of the stars, or
the diameter of the race tracks on which
they run. He pointed out way, how
ever, by which they might be found out
| if one could only make observations
sufficiently precise; 1t depends upon the
use of the speotrosoope, that wonderful
| instrument which has almost recon-
| structed astronomy within the last 40
| years.
| When We look at star with the SPEC
| troscope, we see, instead of a star, mar
row stripe of family colored light, with
certain dark lines across 1t and If star. 10
coming toward us these lines are all
pushed out Of their natural position q
| little toward the blue end of the spec
trum, while if it is receding they are dis
placed in the opposite direction. BY care
| FIJI measurements on the lines one can
therefore find out whether star Is NOV
| ing toward or from us, and how fast.
Now for the application;
Dr. Vogel, OF Potsdam, in Germany.
first succeeded III making the necessary
observations in 1889. He arranged an
instrument with which he photographed
the spectrum of the star in all stages of
its revolution, and by measuring the
photographs under powerful microscope
he showed that about II hours before the
minimum the bright star is receding
from us at the tremendous rate of 2615
l l. l. nft In
minimum it is rushing toward US With
the same speed. We know, then, the
circum ference of the circle on which this
star moves by simply multiplying the
number of seconds in SO hours by its We
locityof 2615 miles second; and all the
other Dimensions Of the figure follow cas-
lily from this.
Here are Vogel's results, which, now
ever, are not to be considered absolutely
exact, but only as near the truth as we
can get at present, and probably very
nearly right, the bright star being des-
ignated as A and the dark body as b;
Distance between centers of
A and B. 3,o23, 900 miles
Diameter Of A, LOGO, 900 miles
Diameter Of Is, $50, 900 miles
Velocity of A, 26k miles per second.
Velocity of B. 55 miles per second.
According to this A is considerably
| ldTBsr butU uU6 sui, duo ID ID d UElhe
smaller but from the motion of the
bodies it can be shown that their united
mass is only about two thirds that of the
sun, and their density only one-fourth
. as great; so that they are much lighter
than water and cahnot be solid bodies
but only heavy olouds-A being much
more brilliant than the sun, while B, fol
some reason not yet determined, is dark.
) A1gol is the only fixed star in all ths
heavens whose size we know; as for al
the rest, we can only guess at their rea
: magnitude. But this is not all the
. strange story Of our star. Observation
has made it plain that the interval be
tween it's minima has been slowly chang
ing for the past hundred years. frs
, lengthening but later shortening, 81
that at present it is about six second
shorter than it was in Goodricke's time.
MIR. Chandler Of Cam bridge, has shown
that this effect runs though its change
, in about 100 years. and can be explained
!. by surprising that Algol and its com
L panion are both moving together in
=, great orbit, as large as that of the plane
i Uranus, uder the attraction of some in
visible body that controls the movement
1 There may be. however, some doubt as t
: this explanation, since Tisserand, one o
-