AMERICA-AUSTRALIA: A new planet forms

Astronomers have released the first close-up images of a young planet in the process of being formed. The research aims to shed light on the ways in which planets and solar systems begin.

Dr Adam L Kraus of the University of Hawaii and Dr Michael J Ireland of Macquarie University in Sydney published their discovery of the planet LcKa 15 b in the Astrophysical Journal last month. Kraus presented their findings at NASA's Goddard Space Flight Center meeting on 19 October.

"LcKa 15 b is a gas giant, similar to Jupiter," the astronomers said. "There have been quite a few detections of Jupiter-like planets in recent years but we've caught this one at the beginning of its life-cycle and orbiting a young, relatively nearby star."

Using the 10-metre Keck telescopes in Hawaii and a precision optical technique called aperture mask interferometry, the astronomers were able to capture the ground-breaking images for the first time of a planet surrounded by dust and gas.

They said the dusty matter was likely being deposited onto or ejected from the object. Such direct observation had not been possible before because light from the star was usually too bright to make accurate measurements. But the optical technique enabled the astronomers to account for the starlight so they could still capture a high resolution image.

Aperture mask interferometry involves placing a small mask consisting of nine holes in the line of light collected from a star, which is then amplified by a giant telescope such as the Keck in Hawaii.

"We can then manipulate the light and cancel out distortions," said Kraus. "It's enabled us to see inside disks of dust and gas around young stars closer than ever before. The gaps in those disks are the perfect zone for young planets in the process of formation."

Kraus and Ireland began searching for young planets through a survey of 150 young dusty stars in star-forming regions but refocused on a dozen stars as their search quickly yielded results.

"LkCa 15 was only our second target and we immediately knew we were seeing something new," said Kraus. "We knew it was more complex than a single companion object, so we collected data several times and at differing wavelengths over 12 months to get a clearer picture.

"What emerged is that we had indeed captured a young gas giant in the process of formation."

Guesses had been made previously about what this might look like, but to finally see it was a real milestone, the two astronomers said. They plan to continue their observations of nearby young stars in their efforts to construct a clearer picture of how planets and solar systems form.

Studying such systems could help astronomers to understand more about Earth's solar system in relation to others 'out there'. "It's one of those big questions - how unique are we really?" they said.