Accreting protoplanets in the LkCa 15 transition disk

25 November 2015

Stunning images of an alien planet nursery 450 light years away have been captured by a team of scientists for the first time. One of the newborn planets is glowing, as a maelstrom of dust and particles rains down on it and gets heated to ferocious temperatures.

An artist's impression of the planetary system in the making. Photo: Sydney University
An artist's impression of the planetary system in the making. Photo: Sydney University

A star known as LkCa 15 lying 450 light years from Earth has exhibited all the trappings of an expectant parent: it is surrounded by a vast disk of dust and gas making an ideal environment for planets to grow. Furthermore the dust shows distinct signs of disturbance: something within has eaten away part of the disk, clearing a gap.

Now a team from the University of Arizona and including researchers from the University of Sydney has released new images of this system. The researchers' results were published today in Nature.

The way any planetary system is assembled is a very hot topic in astronomy. - Professor Peter Tuthill.

The work was led by two University of Arizona graduates, Steph Sallum and Kate Follette, who is doing a post-doc at Stanford University. Astrophysicist professorPeter Tuthill from the University of Sydney was part of the collaboration.

Researchers are just now being able to image objects that are close to and much fainter than a nearby star. Co-author of the paper, Professor Tuthill, said the images provided unambiguous evidence. "This is the first time we've imaged a planet that is definitely still in the process of forming."

The photo provided the proof: "The difficulty had been that when you have indirect evidence, there are always alternate explanations that might fit the data," Professor Tuthill said.

Professor Peter Tuthill. Photo: Chris Bennett
Professor Peter Tuthill. Photo: Chris Bennett

"Results like this have only been made possible with the application of a lot of very advanced new technology to the business of imaging the stars."

Instruments and techniques that have made that difficult observation possible include the Large Binocular Telescope, or LBT - the world's largest telescope, located on Arizona's Mount Graham - and the University of Arizona's Magellan Telescope and its Adaptive Optics System, MagAO, located in Chile. The breakthrough was possible because the Large Binocular Telescope was purpose-built, incorporating a novel imaging technique to sharpen the images.

Meanwhile, Magellan's adaptive optics system MagAO was used to corroborate the discovery.

The paper, Accreting Protoplanets in the LkCa 15 Transition Disc was published in Nature on 19 November.

A video including the first-ever images and animation can be viewed here.

Contact: Vivienne Reiner

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