Only 25 light years away and three times larger than the Sun, the youthful Vega has a giant gaseous planet about the size of Neptune that orbits at the roughly equivalent distance of Neptune, they say.

This is good news, because it means there is plenty of room inside that wide orbit for small rocky planets to develop that could be similar to the Earth.

The study was carried out by astronomers at Britain's Particle Physics and Astronomy Research Council, who made observations using a highly sensitive submillimetric camera at the James Clerk Maxwell telescope in Hawaii.

The camera showed a disk of "very cold dust" whirling in orbit around the star, and at least one large gas planet that over an estimated 56 million years had migrated to a distant orbit.

"The irregular shape of the disk [around Vega] is the clue that it is likely to contain planets," lead author Mark Wyatt said in a press release.

"Although we can't directly observe the planets, they have created clumps in the dust around the star."

Planetary giants play a key role in the developing of solar systems. Their gravitational field attracts debris, essentially vacuuming up all the material in their neighbourhood.

If they are too close to the star, that prevents the formation of rocky planets like Mars, Earth, Venus and Mercury, of which only Earth is at a suitable distance from the Sun to sustain life as we know it.

But if the gas giants are too distant, orbiting debris can smash into planets in closer orbit, wiping out any life on it.

Jupiter, in fact, is believed to have played a vital part as the Earth's gatekeeper -- its distance from the Sun has helped nurture life on this planet by absorbing dangerous space rocks.

More than 100 planets have been discovered around other stars, but in almost every case, they are big gassy behemoths the size of Jupiter that orbit close to their sun.

The study is published in the United States in The Astrophysical Journal, the press release said.

SPACE.WIRE