November 13, 2008 - Sky and Telescope News
For years, astronomers have been racing one another to take the first picture of a planet orbiting another star. Over the past few years, several teams have claimed to have directly imaged an extrasolar planet. But in each case, there were lingering questions about the nature of the purported planet. The objects seem unusually massive for planets, and each orbits much farther from its host star than Pluto orbits the Sun. Many astronomers argue that these objects are more accurately described as failed stars (known as brown dwarfs) rather than true planets, because they probably formed from collapsing gas clouds, like stars.
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The HR 8799 planets were imaged by a team led by Christian Marois (Herzberg Institute of Astrophysics, Canada). This group used the 10-meter Keck II telescope in Hawaii and the 8-meter Gemini telescope in Hawaii to image three pinpricks of infrared light orbiting HR 8799, a magnitude-6 star in the constellation Pegasus. Besides using an occulting mask to blot out the star’s light, the team used adaptive optics to compensate for the blurring effects of Earth’s atmosphere.
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