PORTLAND, Ore. An observatory in Hawaii has harnessed adaptive optics to produce visible light photographs of the first three-planet solar system.
The three gas giants, larger than Saturn and Jupiter, are orbiting the star HR8799, 130 lights years from Earth in the constellation Pegasus.
Last week, NASA released photographs of a single planet 25 light-years away in the the Southern Fish constellation. The photos were taken by the 2.4-meter Hubble Space Telescope.
The much larger telescopes at the Keck Observatory on Maui used adaptive optics techniques to render photographs rivaling those made by Hubble. The technique canceled out the distorting effects of the atmosphere. The resulting photographs of the three gas giant exoplanets (planets outside our solar system) were made by a team of Canadian, U.S. and British astronomers.
|Keck Observatory's 10-meter telescope confirmed the Gemini 8-meter telescope's photograph of three gas giant planets orbiting the star HR8799 in the constellation Pegasus.|
Scientists have long inferred the presence of planets orbiting distant stars, citing the gravitational effect they exert on their star. Over the last decade, 326 planets have been indirectly detected based on their gravitational effects. Improved adaptive optics are enabling the largest ground-based telescopes to image the exoplanets in greater detail.
So far, only gas giant planets less than 60 million years old were thought to be bright enough to be visible from Earth. Exoplanets are not bright enough to photograph with existing telescopes.
The research team, led by Christian Marois of the National Research Council (Victoria, B.C.), captured images using telescopes at the Gemini and Keck observatories. Genimi's 8-meter (26 foot) mirror initially photographed two of the planets; Keck's 10-meter (32 foot) mirror confirmed the finding with photographs of all three planets. Photographs of the star system, dubbed HR 8799, show three planets measuring about ten times the mass of Jupiter. HR8799 is barely visible to the naked eye from Earth.
The Gemini and Keck telescopes used adaptive optics to render photographs using post-processing techniques that removed the central star's light, leaving only the planets and dust belt. Called Angular Differential Imaging, the data-reduction technique uses field-of-view rotations to suppress bright star light with post-processing algorithms.
With atmospheric distortion suppressed, fainter light from the exoplanets shone through. As the telescope rotated, a data reduction pipeline subtracted starlight from multiple images, which were then aligned and combined to provide enough sensitivity to photograph the distant planets.