For years now, astronomers have been finding evidence of planets orbiting around other stars, and they've even managed to directly image some of these 'exoplanets'. Now, thanks to the Gemini Observatory's new planet imager they can get the best pictures yet of distant worlds and even take a good look at their atmospheres.
"Most planets that we know about to date are only known because of indirect methods that tell us a planet is there, a bit about its orbit and mass, but not much else," Bruce Macintosh, the Lawrence Livermore National Laboratory physicist who led the team that built the new imager, said in a statement. "With GPI we directly image planets around stars — it's a bit like being able to dissect the system and really dive into the planet's atmospheric makeup and characteristics."
The Gemini Planet Imager (GPI) took almost 10 years to complete, and began its first observations back in November 2013. One of the first targets the astronomers pointed it was the young star HR4796A (pictured above), which is the central partner in a binary star system with a distant red dwarf companion. The images captured by GPI have the star blocked out to prevent it from interfering with the rest of the image, but the thin band of dust that surrounds the star is clearly visible. On the left is the normal light image, while the right shows it under polarized light. The fact that the 'back' side of the dust band disappears in the right-hand image shows that it's highly-polarized light reflected by the objects in the band.
Another target was the relatively-nearby and well-studied star Beta Pictoris. The resulting image show its planet Beta Pictoris b — a gas giant roughly 65 per cent bigger and at least four times more massive than the planet Jupiter — glowing in the near-infrared due to the heat of its formation. Although the planet may still look like an indistinct blob of pixels, the image GPI captured is the best one of the system so far, was gathered the fastest of any previous image, and the imager is able to take a spectrum of each pixel to gather as much information about the planet as possible.
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Every planetary detection method we've been using so far has its benefits and its limitations. Watching for transits, like Kepler did, needs the orbit of the planet to be roughly lined up with out point of view, otherwise we'll miss them. Other methods need planets to be very large or very close in (or both), or they only supply a limited amount of information. GPI likely won't be the last word in planet detection, since even with the most advanced adaptive optics system yet, this ground-based observatory is limited to finding Jupiter-sized worlds. However, the technology that went into the system could easily lead to even more amazing discoveries in the future.
"Some day, there will be an instrument that will look a lot like GPI, on a telescope in space," Macintosh said in the statement. "And the images and spectra that will come out of that instrument will show a little blue dot that is another Earth."
(Images courtesy: Gemini Observatory)
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