Evening star., 1951-11-02
odd Stars Flicker Out
AS New Ones Are Born
DR.. Splitter Reports on Studies
OF Two Distinct Families
By Thomos R. Henry

The "old stars" are Pickering out. New
ones constantly are being born out Of
cosmic dust clouds to take their places.
Otherwise the universe would be doomed
to everlasting darkness.
This is the thesis presented to the
Philosophical Society of Washington by
DR.. Lyman Splitter, jr, of the Princeton
University Observatory.
1t now is recognized. he explained, that
the universe contains two distinct star
families. One consists of medium bright
objects moving at extremely high
velocities ranging from so to 18o kilo-
meters a second. Their composition is
that of primevai matter-about 10000
parts of hydrogen to 1000 parts Of
helium, with about ten parts of carbon,
oxygen and nitrogen and one part of the
metallic elements.
For various sound reasons, he said, it
may be assumed that these are "origi-
mails" which came into existence at the
beginning of the universe about three
billion years ago. How 1t happened and
what went before nobody knows.
Theory Generally Accepted.
Astronomers now generally accept the
theory that most of the light and heat
OF stars comes from the continuous COM
bination, at very high temperatures, of
hydrogen atoms to form helium-the
mechanism of the proposed H-bomb
which it now seems impossible to dupli-
cate on earth. A star can shine only
as long as its hydrogen, the principal
constituent, holds out. When this ap-
proacheS exhaustion, it becomes q
burned-out cinder in the sky, impossible
to detect except rarely by its gravita-
tional effects on other objects.
Three billion years is long time and
it can be assumed. DR.. Splitter said, that
many of the primeval stars have long
since disappeared. Only the slower burn
ing, less luminous ones still persist. These
will drop out one after another until
eventually all are gone.
But there Is second type of stars of
which the sun, and all the others in this
neighborhood of space. are good ex-
amples. Some of them are enormously
large and enormously hot. AL turn
slowly on their axes and move slowly
through space. So far as the major ele-
ments, hydrogen and helium, are con-
cerned they have about the same compo-
sltlon as the primeval stars, but they
contain twice as much carbon, nitrogen
and oxygen and four times as much of
the metallic elements. Many of them
burn out rapidly. Yet there is no evil
dence Of lessening number of stars.
A solution of the puzzle comes, DR..
Splitter reported, when it is observed
that the second family are all found in
extremely dusty parts of the Milky Way
galaxy. The primeval stars nearly all
are found in essentially dust-free re-
gionS. The conclusion is that the SEQ
ond type. including the sun, have been
formed, and are continually being
formed, out Of this cosmic dust As
tronomerS can postulate, at least, how
it happens.
No Space Absolutely Empty.
There is no such thing as absolutely
empty space. The regions between the
stars in the Milky Way galaxy contain
at least one atom OF hydrogen per cubic
centimeter. But in some regions, notably
In this part OF the Milky Way, the con-
centration is many times this. Great
cesmlc clouds shut off the light of the
stars which lie beyond them. Such
clouds. for example, forever hide the
center of the galaxy. At their greatest
density. OF course, they are far more
tenuous than the finest vacuum ever
attained on earth. Given such cloud of
a certain size, DR.. Splitter said a method
OF star formation can be formulated.
Atoms must be brought together first
to form particles. Even in the thickest
cloud the attraction of gravity between
atoms probably is much too small for
this sort of cohesion to come about.
But there is another force which, neg
ligible and essentially unreasonable on
earth, assumes enormous proportions in
the depths Of space. This is the pres
sure OF light. Rays of light, coming
IN from all directions, tend to push
the atoms together, aided by the fact
that each of them throws a shadow
within which there is no resistance to
this pressure.
The eventual result. Dr. Splitter says.
is the eventual formation of relatively
heavy particles-that is, grains about q
three e-hundred- -thouSandth of a CEN
timeter in radius.
such grains, he says, constitute the
seeds" OF new stars. 1t might almost be
said that the stars are growing from
seed sown in empty space by light. The
particles exert a mutual attraction be-
tween themselves. The light pressure
pushing them together continues, and
in few million years the density be-
comes sufficient to constitute new star.