German astronomers discover "giant baby" planet in deep space

Society Materials 11 February 2008 07:18 (UTC +04:00)

( dpa ) - German astronomers have discovered a "giant baby" planet in deep space which they say has a mass 10 times as dense as Jupiter but is a scant 10 million years old - a newborn by cosmic standards.

The scientists at the Max Planck Institute for Astronomy in Heidelberg say it is the youngest known planet outside of our solar system.

Its host star is still surrounded by the disk of gas and dust from which it was only recently born. It orbits its mother star every 3.65 days.

This discovery allows scientists to draw important conclusions about the time spans involved in planet formation.

Estimated to be only 10 million years old, the newly discovered planet is only 0.2 per cent of the age of our solar system. Our Earth is 4.5 billion years old, and the Sun around 100 million years older than that.

The newly formed planet orbiting a young star offers the first observational evidence for the long-held theory that planets form early, within the first 10 million years of a parent star's life, according to a new study.

Until recently all of the 250-plus planets outside our solar system have been found around much older stars - 100 million years of age or more.

But now a research team led by Johny Setiawan of the Max Planck Institute for Astronomy in Heidelberg, Germany, detected a newborn extra-solar planet - or exo-planet - around a star that's between 8 million and 10 million years old.

The exo-planet is still linked to the dusty disk of material surrounding its parent star.

With this new find, Setiawan said, so-called proto-planetary disks have at last earned their name.

"It is very exciting to know that things we called 'protoplanetary' disks are indeed protoplanetary. They form planets!"

Setiawan and colleagues describe the findings in the journal Nature.

The new planet's star, known as TW Hydrae, is 180 light-years from Earth in the constellation Hydra. Although TW Hydrae is our galactic neighbour, the young planet it hosts is too small and distant to be seen with modern instruments.

Instead astronomers spotted the exoplanet using an indirect technique called radial velocity, according to a press release from the Heidelberg institute.

This method measures the effect of the gravitational tug of a planet on its host star's movement.