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Russia's Top Astronomer
Comments On Pulsar Signals

"As interesting a development
for science now as a trip to the
moon" said a leading Russian astronomer,
Prof. J. S. Shkovsky, of
a recent pulsar discovery. This discovery
was made by two National
Radio Astronomy Observatory astronomers,
and is felt by Mr.
Shklovsky to practically explain
what pulsars are.

Mr. Shklovsky was visiting the
National Radio Astronomy offices
at the University Tuesday, and delivered
the third annual Karl G.
Jansky lecture Tuesday night. He
heads the radio astronomy department
of the Sternberg, Astronomical
Institute in Moscow, and is
regarded as one of the world's
leading astrophysicists.

In an interview Tuesday afternoon,
Mr. Shklovsky spoke on the
recent work of two NRAO radio
astronomers, David Staclin and Ted
Reifenstein. The two men discovered
pulsar, or emitter of extremely
regular radio signals from space,
within the Crab Nebula, the filmy,
gaseous remains of a supernova
explosion. In the opinion of Mr.
Shklovsky this discovery shows "
quite possibly" that the pulsars are
neutron stars, objects the astronomers
believe should theoretically
exist after a large star explodes. In
any case the new observation will
"undoubtedly give new insights
into pulsars".

When stars undergo a supernova
explosion, they rapidly increase in
brightness, at times reaching a
brilliance of 100 million suns. Much
of the star's gases are blown into
space.

The central core of these stars
may be pulled together by gravitational
forces in this rare event. The
matter in this core would then be
extremely dense. If the original star
was about the size of our sun the
core would become a white dwarf
star about the size of earth. If the
star was about two and a half times
the size of our sun, the resulting
core would be a neutron star with a
diameter of about ten miles, due to
the increased gravitational attractions.

Pulsars have been suspected to
be either white dwarf stars, which
have been detected, or neutron
stars, which have not been detected,
since their discovery earlier
this year. This new evidence suggests
to Mr. Shklovsky that pulsars
are indeed neutron stars. He further
suggests that their regularity of
radio emission is due to the rotation
of the star, which swings a
radio source like a searchlight, and
the star's oscillation, which gives
rise to signals between the large
pulses.

One of Mr. Shklovsky's major
contributions to astronomy is the
development of theories related to
supernova remnants, their origins
and evolution.