Astronomers say they have evidence for Earth-like planets orbiting a nearby
star, making it more like our own Solar System than any yet discovered.
By Dr David
BBC News Online science
The star, Vega, is one of the brightest in the sky, only 25 light-years
The clumps rotate around the star approximately once every 300 years
It is three times larger than our Sun and, at 350 million years old, much
younger as well.
Vega has a disc of dust circling it, and at least one large planet which
could sweep debris aside allowing smaller worlds like Earth to exist.
The analysis, by astronomers from the Royal Observatory, Edinburgh, is
published in The Astrophysical Journal, and is based on observations taken
with one of the world's most sensitive cameras.
The device, the Submillimetre Common-User Bolometer Array (Scuba), is
attached to the James Clerk Maxwell radio telescope in Hawaii.
Its detailed images of Vega and its environment confirm the presence of a
disc of very cold dust (-180C) in orbit around the star.
New computer modelling techniques show that structure seen in the disc 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 disc contains a Neptune-like planet
"The shape of the disc is the clue that it is likely to contain planets,"
says Mark Wyatt of the Royal Observatory, Edinburgh.
"Although we can't directly observe the planets, they have created clumps in
the disc of dust around the star."
If this is the case then it may mean that Vega has a planetary system like
Subject to test
The Vega system may have evolved a similar way to our Solar System with gas
giants such as Neptune forming close to the Sun, and then being pulled out to
their current orbits by gravitational interactions with their neighbours.
During this process such giant planets suck in all the debris that would
otherwise pound young planets, allowing life to develop more easily upon
The idea can be tested in two ways as Wayne Holland, who made the original observations, explains: "The model predicts that the clumps in the disc will rotate around the star once every 300 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 disc's clumpiness which can be confirmed using the next generation of
telescopes and cameras."