A computer graphic of the youngest planet

New Delhi, Jan. 2: Astronomers have detected the youngest planet so far, a newborn world located in the planetary nursery of a distant star only 10 million years old.

Scientists at the Max Planck Institute for Astrophysics in Germany used a telescope in Chile to pick up indirect evidence of the planet orbiting a star 180 light years from the solar system, in the constellation Hydra — the snake.

The solar system is at least 4.5 billion years old, but until now the average age of planets discovered outside the solar system has been about two billion years.

The new planet provides the first direct evidence for the theory of how planets are born in the so-called protoplanetary disks of gas and dust along with their host stars, the scientists said in a research report to appear in the journal Nature tomorrow.

“This is the first planet discovered in its nursery,” said Johny Setiawan, lead author and a team member. “We can see the connection between the newborn star, the planet, and the place where it was born,” Setiawan told The Telegraph.

Astronomers have long hypothesised that planets form out of protoplanetary disks, but until now there was no evidence of a star-disk-planet system.

The planet, TW Hya, has a mass nearly 10 times that of Jupiter and is so close to its host star that it completes its orbit every three-and-a-half Earth days.

The discovery also allows scientists to set a time limit for the birth of planets. “The process has to be fast. The planet formation time must be shorter than 10 million years,” Thomas Henning, director of the Max Planck Institute for Astrophysics told The Telegraph.

“This is the youngest planet ever discovered. We know the age of the host star is about ten million years,” Henning said.

The astronomers weren’t expecting to find an infant planet outside the solar system because the environment around young stars makes it difficult to detect the subtle orbital wobbles — the signatures of extrasolar planets.

“It’s a big surprise,” said Setiawan. “We are lucky the planet is big enough that we could detect the signal. We didn’t expect a planet there, but it’s really there.”

“The other surprise was that planet TW Hya is relatively massive and already located closer to the star than the inner edge of the disk,” Henning said.

In earlier observations, astronomers have spotted young stars surrounded by protoplanetary disks, but no planets had been found in them. Until now.

Over the past decade, astronomers have found more than 270 planets outside the solar system, most giant planets, and all of them orbiting much older stars.

Although TW Hya is the only planet detected so far around its host star, it is possible more planets might also have formed in the protoplanetary disk.

“We plan to continue observations,” said Setiawan. The Max Planck team used a telescope in Chile managed by the European Southern Observatory and the La Silla observatory to find TW Hya.

Three years ago, scientists at the University of California, Berkeley, had discovered a young star only 12 million years old, but at the time were unable to detect any planets around it.

Planet hunters at the US National Aeronautics and Space Administration had also indicated that a cloud of dust around a star named CoKu Tau 4 only one million years old may have planets.

But the Max Planck astronomers available evidence suggests that TW Hya is indeed the youngest planet.