The Exotic World of Neutron Stars
NASA: We have booster ignition and liftoff
of Columbia, reaching new heights for women
and X-ray Astronomy.
Martin Elvis: The main thing Chandra does
is take these superb, sharp images.
Narrator: Ordinary matter, or the stuff we
and everything around us is made of, consists
largely of empty space. This is because matter
is made of atoms, and an atom is a cloud of
electrons orbiting around a nucleus composed
of protons and neutrons. Suppose we could
generate a force strong enough to crush all
the emptiness out of a stone roughly the size
of a football stadium. The stone would be
squeezed down to the size of a grain of sand
and would still weigh 4 million tons!
Now imagine something that dense that is not
the size of a sand grain, but rather the island
of Manhattan. Thats a neutron star, one of
the most exotic objects in the Universe. Slavko
Bogdanov of the Harvard University explains
how neutron stars are born.
Scientist: Neutron stars are created when
a massive star runs out of fuel and collapses.
As the star collapses, the density becomes
so immense that protons and electrons are
squeezed tightly together to form neutrons.
The end result is a star only 20 km across
but weighing 1 1/2 times more than our sun
and made up mostly of neutrons. These exotic
objects possess enormous gravitational fields,
about 100 billion times stronger than what
we experience on Earth and have very strong
magnetic fields.
Narrator: Once a neutron star is formed, however,
it does not mean that it just sits quietly
in the cosmos. Rather, neutron stars have
been found to do some incredible things that
astronomers are still trying to understand.
Scientist: Neutron stars are the most rapidly
rotating stars we know about, with the fastest
spinning at an incredible rate of over 700
times per second. For many neutron stars,
the strong magnetic fields and fast rotation
create a giant electric generator which forms
a deadly beam of high-energy particles. As
the neutron star rotates, the radiation from
the particles appears to pulse, analogous
to a rotating lighthouse beam. Such a neutron
star is called a pulsar. The wind of fast-moving
particles generated by a pulsar can also produce
a large glowing cloud surrounding the star,
called a pulsar wind nebula. Most of the radiation
from pulsars is observed at X-ray energies
so Chandra is a valuable tool in the study
of these intriguing objects.
Narrator: So while some neutron stars are
these stellar whirling dervishes, others are
intriguing in other ways. For example, there
is a class of neutron stars called magnetars
that have magnetic fields that are about a
quadrillion times the Earths. (Thats a one
followed by 15 zeroes for those keeping track.)
Dr. Bogdanov explains what these intense magnetic
fields can do to a star.
Scientist: The immense magnetic field of a
magnetar exerts enormous strain on the crust
of the neutron star. On rare occasions, the
strong magnetic forces can break apart the
crust resulting in a powerful starquake, similar
to how upheaval within the Earth causes earthquakes.
Such starquakes are among the most violent
events in the Universe, and release tremendous
amounts of energy much of it in the form of
X-ray radiation. By catching one of these
outbursts in the act and following its behavior
over time with X-ray telescopes such as Chandra,
we can learn a great deal about the extreme
conditions at the surface of these exotic
stars.
Narrator: Clearly, neutron stars are unlike
anything we know about here on Earth. And
because they are so extreme, they give scientists
a chance to test their ideas about matter
in a way that just cant happen in a laboratory.
No matter what flavor the neutron star, each
one is a chance to learn about the fundamental
laws of physics that rule our Universe.
