Distant planet's portrait wows astronomers

A crisp portrait of a planet 56 light years away has been captured by a new high-tech planet-hunting camera developed largely by Canadians.

The Gemini Planet Imager snapped an "amazingly clear and bright" image of the gas giant Beta Pictoris b after an exposure of just one minute, said Quinn Konopacky, a University of Toronto researcher who co-authored a new scientific paper describing the feat.

"I was very, very excited," recalled Konopacky of her first time seeing the planet's portrait, in an interview with CBC News Monday.

The Gemini Planet Imager produces clear images of planets such as Beta Pictoris b (bright spot) by removing glare from the star they orbit (centre). The light from the star has been subtracted from this image, which was published in the journal PNAS. (Gemini Planet Imager/Image processing by Christian Marois, NRC Canada)

Beta Pictoris b is several times larger than Jupiter, the largest planet in our solar system.

The new image and information about the planet teased out of the image data are being published in the journal Proceedings of the National Academy of Sciences this week by an international team led by Bruce Macintosh of Stanford University and Lawrence Livermore National Laboratory in California.

The Gemini Planet Imager, billed as the "world's most powerful exoplanet camera" captured its first portrait of an exoplanet — a planet outside our solar system — shortly after it was installed on the Gemini South telescope in Chile in November.

"It was almost straight out of the box," said Konopacky, who used the data from the instrument to confirm the planet's distance from its star – about the same as the distance between the sun and Saturn.

The way the planet stands out from the background in the images "is basically unprecedented," she added.

Beta Pictoris b was first imaged by Canadian scientists in 2008, but previous images were "noisy" — that is, they were fuzzy the way analog TV images used to be if the signal wasn't good.

In comparison, the images from the Gemini Planet Imager are like high-definition TV where "everything just pops," Konopacky said.

Cutting the glare

Typically, it's hard to see planets with a telescope and camera because of the glare from the stars they orbit, said René Doyon, an astrophysicist at the University of Montreal who also co-authored the paper.

"This instrument is designed to reduce glare and it reduces by a factor of 10," said Doyon, who helped build part of the device in his lab. Other parts were built at the National Research Council of Canada in Victoria, B.C., and at the University of Laval.

The camera cuts glare by using a device called a coronagraph to block the light from the star. In this case, the star was very bright because it is much younger than our sun and twice as massive. Beta Pictoris b is located slightly closer to its star than Saturn is to our sun.

The device didn't find any new planets orbiting the same star as Beta Pictoris b.

600-star survey

But astronomers are hoping it will make some new planetary discoveries around 600 other nearby stars that it will start surveying this year.

Current techniques for discovering planets rely on them to either:

• Block part of the light from a star as they pass in front of it.
• Or use their gravity to pull on the star and make it wobble detectably.

Those techniques can only detect planets with orbits in certain orientations relative to Earth and generally require planets to be close to their stars. That's not only because being close to their star allows them to exert a bigger pull and block more of the light from their star. It's also because more distant planets take longer to complete their orbits and therefore pass in front of their star less frequently.

Doyon noted that Jupiter orbits the sun once every 12 years. Beta Pictoris b orbits every 20.5 years. That's not very convenient for astronomers waiting for them to pass in front of their stars.

Meanwhile, Neptune, the furthest planet in our solar system, completes its orbit only once every 165 years.

"You can see that detecting planets at those distances [from a star] is essentially impossible" using the usual methods, Doyon said.

The Gemini Planet Imager should be better able to find planets further away from their stars.

The device can also distinguish between different colours of light that are the fingerprints of certain molecules in the atmospheres of planets, such as oxygen or carbon dioxide.

Konopacky said its discoveries about Beta Pictoris b's atmosphere will be reported in another soon-to-be published paper.

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