Evening star., 1938-07-04
OF STARS
MEN AND ATOMS
Notebook of Science PROGRESS
in Field, Laboratory
and Study.
By THOMAS r. HENRY

New evidence of the 200 -miles-a- Sec
ond rotation of the 30-billion-star galaxy
around its center of gravity and of the
speed of the solar system at right an
giles to this motion was presented before
astronomers of the American AsSocia-
tion for the Advancement Of Science at
Ottawa last week.
Using flaming blue stars 10000 times
as bright as the sun as lighthouses in
the vastness of celestial space, observers
at the Canadian government Observa-
tory at Victoria, B. c., using the second
largest telescope now in operation in
the world, discovered curious paradox
IN the suns motion.
The direction and speed of this mo-
ton can be calculated from shifts in
the spectra of stars. When spectral lines
are shifted toward the blue end in the
spectroscope it is evidence that the lumi-
nous object is getting nearer-either
that it is careening headlong toward the
sun or that the sun is racing toward it.
Astronomers assume that the distant
star is fixed and that the movement is
on the part of the sun. When the shift
is toward the red end OF the spectrum it
means that the sun is moving in the
opposite direction.
The direction Of the solar systems
path is we'll recognized as being toward
point somewhere on the borderline be-
tween the consultations of Hercules and
Lyra. Evidence differs in respect to the
speed. If the bright hydrogen stars
within the celestial plane, represented
by the Milky Way, are taken as points
of reference, it was reported by DR.. w.
E. Harper director of observatory, the
suns velocity appears to be about 1874
kilometerS a second. If the reference
stars are about 100 light years-or the
distance light moving at 10000 miles a
second will travel in 100 years-from the
celestial plane the speed of the solar
system is approximately 18 kilometers
a second. When determined by stars
200 light years out from the celestial
plane the suns rate of motion slows
down to Ill kilometerS a second Thus
far, DR.. Harper said, the Dominion OBJ
servatory astronomers have not even a
plausible theory to account for this
paradox, since the sun, dragging the
earth with it, hardly can be moving at
two speeds in the same direction at the
same time. That is what it looks like
from the present observations.
The solar system, DR.. Harper explain
ed. is taking part in the titanic rota-
tion of the great galaxy to which it be-
longs, but in this direction of motion
the relative positions of the stars to each
other would be expected to remain con-
stant. Thus there would be no red or
blue shifts in the spectrum. But the
sun also is moving across the rotating
stream OF stars toward the Hercules
Lyra position and this is what intro
duces all the complexities.
The paradox, DR.. Harper explained.
seems TO indicate that the rotation of
the stars toward the center Of the galaxy
is much faster than that of those at
various distances away from this center
and that this speedier central motion
introduces complexities in the spectrum
shifts. The new determinations of the
solar systems speed were made possible
by laborious observations extending over
Is years in which the distances and
brightness of l,500 so-called class A
stars were determined.
These are the brightest stars in the
heavens, located in all parts of the
galaxy and believed to include about
one star in every hundred. The majority
of them give Spectrums notable for one
sharp blue line, one of the principle
lines characteristic of hydrogen gas.
Thus flaming hydrogen is believed to
be their most important constituent
In the past the broad assumption has
been made that they were about 10000
times as bright as the SUM- When this
luminosity figure was accepted the par
adox of the suns two speeds of rotation
did not appear. DR.. Harper was able to
devise method, he told the astronomers,
of determining such a stars real bright
ness from certain tell-tale irregularities
in the spectrum.
With this method. while many of the
blue hydrogen stars turn out to be even
more than 10000 times the luminosity of
the sun, many others, including the
great majority which show traces of
metallic element lines in their spectrums.
appear to be only from to 100 times as
bright. This necessitates radically diff
ferent calculations of their distances
and it is from reference to these new
distances. at which they are regarded
for purposes of calculation as fixed stars,
that the new values of the solar system
speed are derived
The brightest of these celestial light
houses, DR.. Harper said, is Alpha Cygae,
the brightest star in the Northern
Crown" Of the heavens. 1t turns out
from the new calculations to be ap-
proximately $4,000 times as luminous
as the sun.
Evidence confirming the rotation of
the celestial galaxy was presented by
Dr. Andrew Mcclellan of the same OBJ
servatory. He made a precise determi-
nation of the orbit of an abscure star in
the northern heavens known in cata-
logues as H. D. 1885, 1t is a double
star, each of whose component celestial
bodies is affected by the gravity of the
other so that both are kept moving in a
eljspsoid orbit.
This orbit was determined by the
spectrum lines emitted by the various
elements in the two stars. All the lines
agreed with the calculated orbit except
those OF calcium, which showed a para
doxical difference. The Victoria observ-
atory astronomers concluded, however,
that they actually were getting two cal
clum lines superimposed upon each
other. One was from the calcium ac-
tually in the star. The other was from
the great clouds of calcium atoms in
interstellar space.
The discrepancy could be accounted
Tor very exactly by the assumption of
the 2OO-mile-a- a-second revolution of the
celestial system about it's center of grav-
ity. The great calcium clouds take part
in this rotation as we'll as the stars