New evidence for Solar-like planetary system around nearby star (Forwarded)

Particle Physics and Astronomy Research Councils
Swindon, U.K.

CONTACTS

Eleanor Gilchrist (Mon- Wed)
PR Officer, ROE
+44 (0) 131 668 8397,

Dr Mark Wyatt
Astronomer, UK ATC
+44 (0) 131 668 8318,

Dr Wayne Holland
Astronomer, UK ATC
+44 (0) 131 668 8389,

Julia Maddock
Press Officer, PPARC
+44 (0) 1793 442094,

Douglas Pierce Price
James Clerk Maxwell Telescope
+1 808 969 6524,

01 December 2003

New evidence for Solar-like planetary system around nearby star

Astronomers at the Particle Physics and Astronomy Research Councils UK Astronomy
Technology Centre (ATC) at the Royal Observatory, Edinburgh have produced
compelling new evidence that Vega, one of the brightest stars in the sky, has a
planetary system around it which is more like our own Solar System than any
other so far discovered.

All of the hundred or so planets that have been discovered around other stars
have been very large gaseous (Jupiter-like) planets orbiting close to their
star. This is very unlike our own Solar System. New computer modelling
techniques have shown that observations of the structure of a faint dust disk
around Vega can be best explained by a Neptune-like planet orbiting at a similar
distance to Neptune in our own solar system and having similar mass. The wide
orbit of the Neptune-like planet means that there is plenty of room inside it
for small rocky planets similar to the Earth the Holy Grail for astronomers
wanting to know whether we are alone in the Universe.

The modelling, which is described today (1 December 2003) in The Astrophysical
Journal, is based on observations taken with the world's most sensitive
submillimetre camera, SCUBA. The camera, built at the ATC, is operated on the
James Clerk Maxwell Telescope in Hawaii. The SCUBA image shows a disk of very
cold dust (-180 degrees centigrade) in orbit around the star.

The irregular shape of the disk is the clue that it is likely to contain planets
explains astronomer Mark Wyatt, the author of the paper. Although we can't
directly observe the planets, they have created clumps in the disk of dust
around the star.

The modelling suggests that the Neptune-like planet actually formed much closer
to the star than its current position. As it moved out to its current wide
orbit over about 56 million years, many comets were swept out with it, causing
the dust disk to be clumpy.

Exactly the same process is thought to have happened in our Solar System, said
Wyatt, Neptune was pushed away from the Sun because of the presence of Jupiter
orbiting inside it. So it appears that as well as having a Neptune-like planet,
Vega may also have a more massive Jupiter-like planet in a smaller orbit.

The model can be tested in two ways as Wayne Holland, who made the original
observations, explains, "The model predicts that the clumps in the disk will
rotate around the star once every three hundred years. If we take more
observations after a gap of a few years we should see the movement of the
clumps. Also the model predicts the finer detail of the disks clumpiness which
can be confirmed using the next generation of telescopes and cameras."

Paradoxically the star barely appears in the SCUBA image because it is far too
hot to be seen with this kind of detector. Vega is, however, easily seen with
the naked eye. It is the third brightest star visible from Northern latitudes
and is bluish-white in colour. Tonight you can see it in the west at around 7pm.

Facts about Vega

* Vega is the fifth brightest star in the sky and the third brightest visible in
the Northern hemisphere.
* It is 25 light years away from the Sun (1AU is the distance between the Earth
and Sun).
* It has a diameter three times bigger than the Sun.
* It is 58 times brighter than the Sun.
* Together with Deneb and Altair, Vega forms the summer triangle.
* Vega is the brightest star in the constellation Lyra, the Harp. The lyre, or
harp, is supposed to have been invented by the Greek God Hermes who gave it to
his half-brother Apollo. Apollo then gave it to his son Orpheus, the musician of
the Argonaughts.
* Vega was the first star ever to be photographed. During the night of July
16-17, 1850 the historic picture was taken at Harvard Observatory using a 15
inch refractor telescope during a 100 second exposure.

NOTES:

The UK ATC

The UK Astronomy Technology Centre is located at the Royal Observatory,
Edinburgh (ROE). It is a scientific site belonging to the Particle Physics and
Astronomy Research Council (PPARC). The mission of the UK ATC is to support the
mission and strategic aims of PPARC and to help keep the UK at the forefront of
world astronomy by providing a UK focus for the design, production and promotion
of state of the art astronomical technology.

The ROE

The Royal Observatory, Edinburgh comprises the UK Astronomy Technology Centre
(UK ATC) of the Particle Physics and Astronomy Research Council (PPARC), the
Institute for Astronomy (IfA) of the University of Edinburgh and the ROE Visitor
Centre.

The James Clerk Maxwell Telescope (JCMT)

The JCMT is the worlds largest single-dish submillimetre telescope. It collects
faint submillimetre signals with its 15 metre diameter dish. It is situated near
the summit of Mauna Kea on the Big Island of Hawaii, at an altitude of
approximately 4000 metres (14000 feet) above sea level. It is operated by the
Joint Astronomy Centre, on behalf of the UK Particle Physics and Astronomy
Research Council, the Canadian National Research Council, and the Netherlands
Organisation for Scientific Research.

SCUBA

SCUBA (the Submillimetre Common-User Bolometer Array) is the worlds most
powerful submillimetre camera. It is attached to the James Clerk Maxwell
Telescope, and contains sensitive detectors called bolometers, which are cooled
to 60 milliKelvin, 0.06 degrees above absolute zero (60 milliKelvin is about
-273.1 Celsius, -459.6 Fahrenheit). SCUBA was built in the UK by the Royal
Observatory, Edinburgh, at what is now the UK Astronomy Technology Centre.

PPARC

The Particle Physics and Astronomy Research Council (PPARC) is the UKs strategic
science investment agency. It funds research, education and public understanding
in four broad areas of science particle physics, astronomy, cosmology and space
science.

PPARC is government funded and provides research grants and studentships to
scientists in British universities, gives researchers access to world-class
facilities and funds the UK membership of international bodies such as the
European Organisation for Nuclear Research,

CERN, the European Southern Observatory and the European Space Agency. It also
contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia
and in Chile, the UK Astronomy Technology Centre at the Royal Observatory,
Edinburgh and the MERLIN/VLBI National Facility.

Websites

* http://www.roe.ac.uk/atc
* http://outreach.jach.hawaii.edu/
* http://www.pparc.ac.uk/

IMAGES:
(These are the highest resolution available.)

[Image 1. SCUBA image:
http://www.pparc.ac.uk/Nw/vega_observations_hires.gif (26KB)]
This is a false colour image of the heat emitted from the dust disk around Vega.
The image shows the disk seen face-on. The disk structure includes two bright
clumps, represented by the yellow and red colours. The star is barely noticeable
and is located at the centre of the image, mid-way between the two clumps. The
dust were seeing is actually confined to a region relatively far from the star:
more than twice as far as the distance from the Sun to Neptune. The lack of dust
close to the star is the first indication that a planetary system is hiding in
the hole. The modelling published today implies that this system looks very much
like our own Solar System.

[Image 2:
http://www.pparc.ac.uk/Nw/vega_with_star_hires.gif (27KB)]
SCUBA image with the position of the star (*) and the predicted position and
direction of the planet (x) marked. The distance between the star and the planet
is equivalent to twice that between the Sun and Neptune.

[Image 3:
http://www.pparc.ac.uk/Nw/horizon_map_hires.gif (7KB)]
Sky map showing the position of Vega tonight at 7pm (1 December 2003 19:00 GMT)