Re: free quarks??

[Larry Cartwright <exit60@CABLESPEED.COM>]

"Michael N. Monce" wrote:
>         A very strange article in the paper this a.m. from Knight Ridder
> service. Makes claim for evidence of unbound quarks in two neutron stars
> by observations from the Chandra spacecraft. Observers are Helfand from
> Columbia and Drake from CfA.  No mention of what sort of x-ray evidence
> would point to this, or why this does not blow the Standard Model to
> shreds.  Can anyone with more information provide some enlightenment?

Here (with thanks to Ron Baalke at JPL) is the original Release from the
people at Marshall and Chandra, along with Chandra website links, which
triggered the articles now appearing in the popular press.

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Dolores Beasley
Headquarters, Washington                   April 10, 2002
(Phone: 202/358-1753)

Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-6535)

Megan Watzke
Chandra X-ray Observatory Center, Cambridge, Mass.
(Phone: 617/496-7998)

RELEASE: 02-65

COSMIC X-RAYS REVEAL EVIDENCE FOR NEW FORM OF MATTER

     NASA's Chandra X-ray Observatory has found two stars --
one too small, one too cold -- that reveal cracks in our
understanding of the structure of matter. These discoveries
open a new window on nuclear physics, offering a link between
the vast cosmos and its tiniest constituents.

Chandra's observations of RXJ1856.5-3754 and 3C58 suggest
that the matter in these stars is even denser than nuclear
matter found on Earth. This raises the possibility these
stars are composed of pure quarks or contain crystals of sub-
nuclear particles that normally have only a fleeting
existence following high-energy collisions.

By combining Chandra and Hubble Space Telescope data,
astronomers found that RXJ 1856 radiates like a solid body
with a temperature of 1.2 million degrees Fahrenheit (700,000
degrees Celsius) and has a diameter of about seven miles
(11.3 kilometers). This size is too small to reconcile with
standard models for neutron stars -- until now the most
extreme form of matter known.

"Taken at face value, the combined observational evidence
points to a star composed not of neutrons, but of quarks in a
form known as strange quark matter," said Jeremy Drake of the
Harvard-Smithsonian Center for Astrophysics (CfA) in
Cambridge, Mass., and lead author of a paper on RXJ1856 to
appear in the June 20, 2002, issue of The Astrophysical
Journal. "Quarks, thought to be the fundamental constituents
of nuclear particles, have never been seen outside a nucleus
in Earth-bound laboratories."

Observations by Chandra of 3C58 also yielded startling
results. A team composed of Patrick Slane and Steven Murray,
also of CfA, and David Helfand of Columbia University, New
York, failed to detect the expected X-radiation from the hot
surface of 3C58, a neutron star believed to have been created
in an explosion witnessed by Chinese and Japanese astronomers
in A.D. 1181. The team concluded that the star has a
temperature of less than one million degrees Celsius, which
is far below the predicted value.

"Our observations of 3C58 offer the first compelling test of
models for how neutron stars cool, and the standard theory
fails," said Helfand. "It appears that neutron stars aren't
pure neutrons after all -- new forms of matter are required."

A teaspoonful of neutron-star material weighs a billion tons,
as much as all the cars, trucks and buses on Earth. Its
extraordinary density is equivalent to that of the nucleus of
an atom with all the typical space between the atoms and
their nuclei removed. An atom's nucleus is composed of
positively charged protons and neutral neutrons, particles so
small that 100 billion trillion of them would fit on the head
of a pin.

Protons and neutrons are composed of even smaller particles
called quarks, the basic building blocks of matter. Enormous
atom-smashers are designed to probe the forces between quarks
and the structure of the nucleus by smashing high-energy
beams of nuclei into each other and observing the violent
aftermath for a fraction of a second.

Drake cautioned that the observations of RXJ1856 could be
interpreted as a more normal neutron star with a hot spot.
Such a model is under consideration by Fred Walter of the
State University of New York, Stony Brook, one of the
discoverers of RXJ1856, which was originally found in 1996 by
the German Roetgen satellite. However, the hot-spot model
requires a very special orientation of the star with respect
to the Earth to explain the absence of pulsations, which
would be expected from the hot spot. The probability of such
an orientation is quite small.

"Regardless of how these mysteries are resolved, these
precise observations are highly significant," said Michael
Turner of the University of Chicago. "They demonstrate our
ability to use the universe as a laboratory where we can
study some of the most fundamental questions in physics."

NASA's Marshall Space Flight Center in Huntsville, Ala.,
manages the Chandra program, and TRW, Inc., Redondo Beach,
Calif., is the prime contractor. The Smithsonian's Chandra X-
ray Center controls science and flight operations from
Cambridge, Mass.

Images and additional information about this result are
available at:

http://chandra.harvard.edu

and

http://chandra.nasa.gov

                        -end-

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Best wishes,

Larry

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Larry Cartwright   <exit60@cablespeed.com>
Retired (June 2001) Physics Teacher
Charlotte MI 48813 USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~