1st December 2003
Issued by the UK Astronomy Technology Centre
New evidence for Solar-like planetary system around nearby star
Astronomers at the Particle Physics and Astronomy Research Council's 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 Celsius) 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
disk's 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 7 pm.
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 Argonauts.
- 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.
SCUBA image: 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 we're
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.
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
Sky map showing the position of Vega as seen from the United Kingdom (and
similar latitudes) tonight at 7pm (1 December 2003
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
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 world's 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
SCUBA (the Submillimetre Common-User Bolometer Array) is the world's
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.
The Particle Physics and Astronomy Research Council (PPARC) is the UK's
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.
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
Press Officer, PPARC
+44 (0) 1793 442094
Dr Douglas Pierce Price
James Clerk Maxwell Telescope
+1 808 969 6524
- UK Astronomy Technology Centre
- Joint Astronomy Centre
- Particle Physics and Astronomy Research Council (PPARC)