Evening star. [volume] (Washington, D.C.) 1854-1972, 1952-12-19
BIue-SheIIed Sturs
Sighted in Milky Way
Atmosphere Extends Far
Above Pleione's Photosphere
By Thomas R. Henry

There are great stars with blue shells
scattered through the Milky Way.
These strange objects have been stud
led through the year by astronomers of
the Carnegie Institution of Washington.
DR.. Paul w. Merrill of the Mount Wilson
Observatory staff has determined the
spectra, the wave lengths Of light emit
ted by luminous object which make it
possible to determine what it is made
Of, Of Is Of these shell stars. according
to the annual report Of the observatory.
Most intensively studied has been the
fifth-magnitude star Pleione in the PIE
ladies, or Seven Sisters, in the northern
heavens. An object about twice as bright
as the sun. it is just below the limit
where it can be seen with the naked eye.
Pleione began acting funny back in 1888.
It's light indicated that it was coming
from flaming hydrogen surrounding the
main star body. This continued until
1903 when the bright hydrogen lines in
the spectrum disappeared. For more
than 80 years it apparently acted like a
normal star of its type. In 1899 the
hydrogen lines reappeared.
Expanse Of Atmosphere.
4AAC oIOO1CS nave 1IlUlCdCCu, says UIl0
report, that the stars atmosphere, COM
posed largely of hydrogen. extended to
an unusual height above the photo
sphere, or light-emitting surface. This
high atmosphere apparently forms a
shell around the whole star formed by
atoms which have moved up from the
photosphere many thousands of miles
into space.
At first shell and star seem to rotate
with about the same velocity but gradu-
ally the speed of the shell increases.
Then it disappears. Eventually, it is
believed, the supply of atoms moving
upward from the philosophers fails and
the shell blows away.
Pleione Is perhaps the most striking
star OF this type, but all vary somewhat
In their behavior. In most Of the stars
studied by DR.. Merrill, the velocities
change slowly with time and some of the
shells appear quite stable. Besides n.y.
drogen there is evidence of a lot Of
metallic atoms in the envelopes.
Among the most curious stars studied
during the year, according to the report.
is one very blue. faint object which,
according to the studies carried out by
DR.. Jesse L. Greenstein Of the Carnegie
staff, must be about half way in size
between stars like the sun and the white
dwarfs the matter of which weighs
several tons per cubic inch. The size
of this body must be somewhat smaller
than that of the planet Jupiter. This
may be similar to some very faint blue
stars found in the globular clusters
which are hung like lanterns around the
edges of the Milky Way.
Such stars, according to the Mount
wilson report. may represent an impor-
tant period in the life history Of stellar
bodies-their collapse on the way to be-
coming white dwarfs. At this stage a.
star has reached the end Of its road.
unless it explodes as a nova or new
STAR" suddenly becoming visible to the
naked eye.
"Technicium Stars"
Inexplicable objects first reported are
"technicium stars" These, their light
lines show, contain considerable amounts
of the radioactive element technicium,
all Of which has disappeared from the
earth and sun billions of years ago. It
now is being made by bombardment Of
the element molybdenum with neutrons
in the Atomic Energy Commissions pile
at Oak Ridge, Tenn. The Carnegie
astronomers have possible explanations
for the appearance of the element in the
far heavens. There is one possibility that
there is non-radioactive form of tech
nicium, no trace Of which ever had been
found on earth. The star itself may
manufacture the element. acting as q
super-atomic pile. None of these ex-
plantations is very satisfactory, they
agree.