Spitzer Telescope Reveals Jet of Matter Around Dead Star

http://www.southampton.ac.uk/mediace...un/06_83.shtml

Spitzer Telescope reveals jets of matter around dead star
University of Southampton News Release
27 June 2006

A team of scientists, including researchers in the University of
Southampton's School of Physics and Astronomy, have shown that black
holes are not the only known objects in the universe to produce
infrared
light from beams of particles being shot into space at nearly the speed
of light.

Previously, these steady 'relativistic jets' were only seen from black
holes which form part of a black hole X-ray binary, a system containing
a black hole orbited by a normal star which is so close that the black
hole's gravity can peel off the outer part of the normal star and suck
in its gas through an accretion disk or disk of matter.

Using the extremely sensitive infrared Spitzer Space Telescope recently
launched by NASA, the team discovered one of these steady jets of
matter
coming from a neutron star (a super-dense type of dead star) in an
X-ray
binary system. For many years scientists have debated whether there was
something unique to black holes that fuelled relativistic jets. It is
now clear that the jets must be fuelled by something that both black
holes and neutron stars share.

Neutron stars form in the death knells of massive stars, when the
pressure at the centre of the star is so large that the electrons and
protons of normal matter combine to form a star made almost entirely of
neutrons. Not quite dense enough to be black holes, they have masses
slightly larger than the Sun's, but diameters about the size of a city,
making them as dense as the nuclei of atoms.

Dr Thomas Maccarone, of the University of Southampton, explains: 'Jets
of matter shot off by black holes are usually observed with a radio
telescope which enables astronomers to isolate the jet from everything
else in the system. However, observing a neutron star's jets with a
radio telescope would take many hours because the jets are very faint.
The Spitzer Space Telescope sees light which is redder than the reddest
colours visible by the human eye and also redder than the light given
off by normal stars.'

Using the Spitzer Telescope, the researchers were therefore able to
detect the faint jet of a particular neutron star, 4U 0614+091, in
minutes even though it is located about 10,000 light-years away in the
constellation Orion. This signal would have taken almost a day to
detect
on the most powerful radio telescopes on Earth. The Spitzer Telescope
also helped the team infer details about the jet's geometry. The team's
data indicates that the presence of an accretion disk and an intense
gravitational field may be all that is needed to create and fuel a jet
of matter.

Dr Maccarone continues: 'For the past 25 years, astronomers have
debated
the importance of a black hole in jet production. By comparing the
behaviour of the relativistic jets seen from neutron star X-ray
binaries
and from black hole X-ray binaries, astronomers have hoped to compare
neutron stars and black holes directly and possibly to see whether
these
jets are extracting the black holes' rotational energy. This discovery
blazes the trail for future studies which should help reveal the nature
of relativistic jets.'


Notes for editors:

1. A computer-generated visualisation of a black hole or neutron
star
X-ray binary system is available from Media Relations on request.

The image was produced using a visualisation tool provided by Rob
Hynes of the Louisiana State University, USA.

2. The research findings are published in the 20 May 2006 issue of
Astrophysical Journal Letters in a paper by Dr Thomas Maccarone,
Professor Rob Fender and David Russell, a PhD student, University
of Southampton; Dr Simone Migliari and Dr John Tomsick,
University
of California San Diego; Dr Elena Gallo, University of California
Santa Barbara, and Dr Gijs Nelemans, Radboud Universiteit in
Nijmegen, The Netherlands.

3. The University of Southampton is one of the UK's top 10 research
universities, with a global reputation for excellence in both
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engineering, health, arts and humanities, the University has
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of ??287 million.

Southampton is recognised internationally for its leading-edge
research in engineering, science, computer science and medicine,
and for its strong enterprise agenda. It is home to world-leading
research centres, including the National Oceanography Centre,
Southampton; the Institute of Sound and Vibration Research; the
Optoelectronics Research Centre; the Textile Conservation Centre;
the Centre for the Developmental Origins of Health and Disease;
and the Mountbatten Centre for International Studies.


For further information:

Dr Thomas Maccarone, School of Physics and Astronomy,
Tel. 023 8059 7548, email:
Sue Wilson, Media Relations, University of Southampton,
Tel. 023 8059 5457, email:

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