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PHOTO CAPTION:

EMBARGOED UNTIL: 2:00 P.M. (EDT) September 24, 1997

PHOTO NO.: STScI-PRC97-32


HUBBLE SEES A NEUTRON STAR ALONE IN SPACE

This is the first direct look, in visible light, at a lone neutron
star, as seen by NASA's Hubble Space Telescope. The Hubble results show the
star is very hot (1.2 million degrees Fahrenheit at the surface), and
can be no larger than 16.8 miles (28 kilometers) across. These results
prove that the object must be a neutron star, because no other known
type of object can be this hot, small, and dim (below 25th magnitude).

The first clue that there was a neutron star at this location came in
1992, when the ROSAT (the Roentgen Satellite) found a bright X-ray
source without any optical counterpart in optical sky surveys. Hubble's
Wide Field Planetary Camera 2 was used in October 1996 to undertake a
sensitive search for the optical object, and found a stellar pinpoint
of light within only 2 arc seconds (1/900th the diameter of the Moon) of
the X-ray position. Astronomers haven't directly measured the neutron
star's distance, but fortunately the neutron star lies in front of a
molecular cloud known to be about 400 light-years away in the southern
constellation Corona Australis.

Credit: Fred Walter (State University of New York at Stony Brook), and NASA