Evening star., 1939-07-20
Scientists Study Stars
Millions Of Times
Brighter Than Sun
30 to 40 q Year Are
Detected at Mt. Wilson,
Paris Session Told
BY THOMAS r. HENRY,
Star Stan Correspondent.

Star Stan Correspondent.
PARIS, July 20.-Once or twice in
every thousand years star 10000
900 to 1000, 900, 900 times as bright as
the sun at the same distance appears
in the sky.
The last one among the $4,000, ,000,-
000-odd stars of the Milky Way gal
axy famed in the Eastern heavens
in 1858, eight years before the land
ing of William the Conqueror.
Studies of these stars, the most
extreme energy outbursts in crea-
ton, were described before a world
conference of astronomers here to-
way by Dr. Walter Baade of the
Mount Wilson Observatory OF the
Carnegie Institution of Washington
He, together with Drs. F. Zwicky and
K. Minkowski of the Carnegie staff,
have been observing them for the
last three years as they appear in
other systems of stars, comparable
in size to the Milky Way galaxy, but
so far distant that their light, NOV
ing at 10000 miles a second, re-
quires several million years to reach
the earth.
30 to 40 a Year.
They started by combing these
extra -galactic systems for novae,
stars ordinarily of about the size
and brightness of the sun, which
suddenly flare up to as much as -00,-
000-fold their ordinary luminosity
and then fade back to normal in a
few weeks. Rarely observable from
the earth, these new stars appar-
entity are quite common in creation.
In some of the nearer external galax-
les, only few million light years
distant, the Mount Wilson observers
detected from 80 to 40 of them
year.
They knew, however, that these
seldom were more than 10000 times
brighter than the sun and would
be too faint to be seen at such enor-
nous distances except in some of the
closest neighbors of the Milky Way
galaxy. In galaxies millions of light
years beyond the possibility of dis
corning a mere nova their photo
graphic plates detected these enor-
nous outbursts of radiation. The
explosion of single star was causing
luminosity equal to that of all the
other millions of stars in the galaxy
combined. Up to now the Mount
Wilson astronomers have detected
nine of them in all the star systems
they have observed. Calculation
shows, DR.. Baade says. that this is at
the rate of one every 612 years per
galaxy. In some of the star systems,
however, they may be more frequent
and in others, perhaps including the
Milky Way galaxy, less frequent.
Old Records Found.
At the time their Investigations
started, no such phenomenon ever
had been observed in the Milky Way
system. Recently, however, old jap
anese records have become available
which indicate that such a super
novae actually was seen in the con-
stellation of Taurus, visible in the
West in late winter, in 1858. In this
same constellation there is a strange
dark nebula with crab-like claws
the so-called Crab nebula-which
long has puzzled astronomers. Re
calculation of the data, DR.. Baade
said, shows beyond much doubt that
this is the end of supernova. More
intensive study of this fossil of the
skies, they believe, may shed new
light on the nature of the process
responsible for such an explosion.
Meanwhile, Dr. Baade said, they
are trying to get some information
from the light itself. as observed in
the distant galaxies. This light,
they find. increases and decreases
generally in about the same fashion
as does that of an ordinary nova
except that it remains at its max
imum brightness for several days.
After that there is very sharp de-
cline-about one-tenth of a magni-
tude a day-for approximately d
month. After that the decline is
much more gradual-about O2 of a
magnitude a day-until it finally
disappears altogether.
Only Two Bands Identified.
1t has been impossible to date, he
said, to get clear spectrum of a
supernova and the astronomers dis
pair of doing this until one appears
in the Milky Way galaxy, which
might be anytime now. They have
been able to identify only two def
mite bands which are those of blue
green visible light.
A recent discovery only adds to
the mystery. Some of the light
bands seem to shift progressively
toward the red end of the spectrum
that is, toward longer wave
lengths-as the phenomenon con-
tinues. Ordinarily this would be
interpreted to mean that the source
of the light, in this case the ex-
ploding star, was moving very rapid
ly away from the observer. There
is no reason to suppose this true in
the case of supernova and the
Mount Wilson astronomers are at
complete loss to explain the queer
red shift.
Perhaps the most surprising re-
suit of the spectroscopic investiga-
tion, DR.. Baade said. is that all the
supernova seems to behave in identi-
cally the same fashion. Spectra of
different ones taken at the same
phases are so closely identical even
in minor details that one cannot be
dicfino,liShed from onnther