Evening star., 1951-06-22
Dwarf Stor Studies Open
New Field in Astronomy
Unknown Until Two Years Ago,
implications Called SturtIinq
By Thomos R. Henry

Flaring dwarf stars, probably the most
numerous of all stars in creation but
which have remained unknown until
two years ago, may have opened up q
new chapter in astronomy.
"The implications are startling" says
DR.. Harlow Shapley Harvard professor
OF astronomy, in report on their sig
nificance to the American Association
for the Advancement of Science here.
They are dwarf, red stars, too small
to appear in any but the most powerful
telescopes. Their average luminosity is
less than thousandth that Of the sun.
Sometimes they are less than ten
thousandth as bright. More than half
of the SO stars nearest, the sun are
of this type, yet they are completely
missed in almost all surveys of the
heavens.
They are. presumably. very old stars
struggling against extinction, DIR.
Shapley points out. At one time they
may have been objects comparable to
the sun but through the millenniums
they have lost most of their masses
through radiation. The sun itself loses
in the form Of light thousands Of tons a
day, as do most other luminous bodies
in the heavens, and eventually all will
become cold cinders in space.
A few years ago. DR.. Shapley said, it
first was realized that these stars were
not dying calmly. Periodically they
flare up to twice. sometimes as much
as four-fold their customary brightness.
Flares of Dying Stars.
These flares are of about the same
magnitude as the flares which take
place every few days on the suns sur
face and which are known to interfere
seriously with radio broadcasting on
earth. The sun is so bright that the
increase in luminosity hardly can be
detected but flares make q very decided
difference with the weak stars.
There are implications in several di-
rections, DR.. Shapley says. One, Of
some practical significance, is that they
may explain the perpetual static Of the
Milky Way where they can be considered
equally numerous as in the neighbor-
hood of the sun.
Superimposed on this static are quite
definite short-wave radio signals. Ex-
cept in few Instances they came from
regions almost devoid of stars. Per-
haps the most notable instance is that
Of the so-called Crab nebula which,
nine centuries ago. was an exploding
star OF about the size of the sun. It
blew up and in few days became
more than million times brighter
than the sun. Now there is only great
mass of gas visible there but, says DIR.
Shapley. presumably blue-hot nucleus
remains buried in this gas from which
the radio signals come. The other
sources are more difficult to explain, but
there is considerable probability that
they are regions where there is a con-
siderable accumulation of these fiaring
red dwarfs. In any event, they can
account for good deal Of the back.
ground static. $50,
New Studies Facilitated.
Perhaps of more significance is the
opportunity they give Of studying the
old-age Of stars.
They are" ;" 1t seems. presumably ap-
preaching a cold senility. They are too
faint to appear In ordinary surveys, yet
they probably are more numerous than
any other type Of star in the universe.
We have opened up suddenly q new
phase in the study Of the evolution Of
StcllaT DOQleS. =. q.
The most specific sources of celestial
radio signals, however, probably remain
objects like the Crab nebula, the remains
OF exploded stars. About 100 of these
have been recorded in the Milky Way
galaxy throughout history.
Three new ones have been added
during the past year, according to an
announcement from Carnegie Institute
OF Technology. Astronomers at the in
stitute's Mt. Palomar Observatory found
them in systematic survey of this
heavens. They reached a brightness
$4,000 times that of the sun in a few
days. although it is probable that they
originally were objects quite similar to
the sun.
The Mount Palomar observers also
have found beyond the Milky Way, in
other galaxies which lie thousands of
light years across voids of empty space.
IL super-novae which reach brightnesses
$50 million times that Of the sun. Such,
1t is likely. was the Crab nebula, the
only known instance of such q phenome.
non in this star system.