This Echo is READ ONLY !   NO Un-Authorized Messages Please!
 ~~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Astronomers find 'home from home' - 90 light years away!

Julia Maddock
Particle Physics and Astronomy Research Council (PPARC)
July 3, 2003

Part 1 of 2

Astronomers looking for planetary systems that resemble our own solar
system have found the most similar formation so far. British
astronomers, working with Australian and American colleagues, have
discovered a planet like Jupiter in orbit round a nearby star that is
very like our own Sun. Among the hundred found so far, this system is
the one most similar to our Solar System. The planet's orbit is like
that of Jupiter in our own Solar System, especially as it is nearly
circular and there are no bigger planets closer in to its star.

"This planet is going round in a nearly circular orbit three-fifths
the size of our own Jupiter. This is the closest we have yet got to a
real Solar System-like planet, and advances our search for systems
that are even more like our own," said UK team leader Hugh Jones of
Liverpool John Moores University.

The planet was discovered using the 3.9-metre Anglo-Australian
Telescope [AAT] in New South Wales, Australia. The discovery, which
is part of a large search for solar systems that resemble our own,
will be announced today (Thursday, July 3rd 2003) by Hugh Jones
(Liverpool John Moores University) at a conference on "Extrasolar
Planets: Today and Tomorrow" in Paris, France.

"It is the exquisite precision of our measurements that lets us
search for these Jupiters - they are harder to find than the more
exotic planets found so far. Perhaps most stars will be shown to have
planets like our own Solar System", said Dr Alan Penny, from the
Rutherford Appleton Laboratory.

The new planet, which has a mass about twice that of Jupiter, circles
its star (HD70642) about every six years. HD70642 can be found in the
constellation Puppis and is about 90 light years away from Earth. The
planet is 3.3 times further from its star as the Earth is from the
Sun (about halfway between Mars and Jupiter if it were in our own
system). 

The long-term goal of this programme is the detection of true
analogues to the Solar System: planetary systems with giant planets
in long circular orbits and small rocky planets on shorter circular
orbits. This discovery of a -Jupiter- like gas giant planet around a
nearby star is a step toward this goal. The discovery of other such
planets and planetary satellites within the next decade will help
astronomers assess the Solar System's place in the galaxy and whether
planetary systems like our own are common or rare.

Prior to the discovery of extrasolar planets, planetary systems were
generally predicted to be similar to the Solar System - giant planets
orbiting beyond 4 Earth-Sun distances in circular orbits, and
terrestrial mass planets in inner orbits. The danger of using
theoretical ideas to extrapolate from just one example - our own
Solar System - has been shown by the extrasolar planetary systems now
known to exist which have very different properties. Planetary
systems are much more diverse than ever imagined.

However these new planets have only been found around one-tenth of
stars where they were looked for. It is possible that the
harder-to-find very Solar System-like planets do exist around most
stars.

The vast majority of the presently known extrasolar planets lie in
elliptical orbits, which would preclude the existence of habitable
terrestrial planets. Previously, the only gas giant found to orbit
beyond 3 Earth-Sun distances in a near circular orbit was the outer
planet of the 47 Ursa Majoris system - a system which also includes
an inner gas giant at 2 Earth-Sun distances (unlike the Solar
System). This discovery of a 3.3 Earth-Sun distance planet in a near
circular orbit around a Sun-like star bears the closest likeness to
our Solar System found to date and demonstrates our searches are
precise enough to find Jupiter- like planets in Jupiter-like orbit.

To find evidence of planets, the astronomers use a high- precision
technique developed by Paul Butler of the Carnegie Institute of
Washington and Geoff Marcy of the University of California at
Berkeley to measure how much a star "wobbles" in space as it is
affected by a planet's gravity. As an unseen planet orbits a distant
star, the gravitational pull causes the star to move back and forth
in space. That wobble can be detected by the 'Doppler shifting' it
causes in the star's light. This discovery demonstrates that the long
term precision of the team's technique is 3 metres per second (7mph)
making the Anglo-Australian Planet Search at least as precise as any
of the many planet search projects underway.

Notes for Editors:

The team is supported by the UK Particle Physics and Astronomy
Research Council, the Australian government and the US National
Science Foundation.

Dr Hugh Jones will be presenting details of the new planet on 3 July
at the "Extrasolar Planets: Today and Tomorrow" conference in Paris.
The conference will be web-streamed live from www.canalu.fr.The paper
describing the new planet has been accepted for publication by the
Astrophysical Journal Letters.

 - Continued -

@Message posted automagically by IMTHINGS POST 1.30
---