First-ever photos of multiple planets orbiting another star
Nov. 13, 2008
Telescopes on land have caught the first real visual images of multiple planets orbiting another star.
The orbiting Hubble Space Telescope has found its own planet, the first so-called exoplanet to be found purely visually.
Gemini Observatory discovery image using the Altair adaptive optics system on the Gemini North telescope with the Near-Infrared Imager (NIRI). Image shows two of the three confirmed planets indicated as "b" and "c" on the image. "b" is the ~7 Jupiter-mass planet orbiting at about 70 AU, "c" is the ~10 Jupiter-mass planet orbiting the star at about 40 AU. Due to the brightness of the central star, it has been blocked and appears blank in this image to increase visibility of the planets.
One set of images shows three giant planets orbiting a star named HR8799 in the constellation Pegasus, about 130 light-years away from the Earth. A light-year is the distance light travels in a year, or 6 trillion miles (10 trillion km).
The planets are several times the mass of Jupiter.
"We finally have an actual image of an entire system," said Bruce Macintosh, an astrophysicist from Lawrence Livermore National Laboratory in California and a member of the team of scientists who made the observations.
"This is a milestone in the search and characterization of planetary systems around stars."
About 300 planets have been found orbiting other stars besides the Earth's sun, but they have been found using indirect measurements, mostly looking at their effects on the gravitational fields of their suns.
"Every extrasolar planet detected so far has been a wobble on a graph," Macintosh said in a statement. "We've been trying to image planets for eight years with no luck and now we have pictures of three planets at once."
Writing in Friday's issue of the journal Science, the astronomers said they used the Keck and Gemini telescopes in Hawaii to get the pictures, which can be seen on the Internet at http://www.gemini.edu.
The images show blurred smudges that the astronomers are sure are the planets.
In the second study, Univ. of California, Berkeley, astronomer Paul Kalas and colleagues used the Hubble Space Telescope to image a planet they call Fomalhaut b, orbiting the star Fomalhaut, which is 25 light years from Earth in the constellation Piscis Australis (the Southern Fish).
Gemini adaptive optics image of 1RSX J160929.1-210524 and its likely ~8 Jupiter-mass companion (within red circle). This image is a composite of J-, H- and K-band near-infrared images. All images obtained with the Gemini Altair adaptive optics system and the Near-Infrared Imager (NIRI) on the Gemini North telescope. Photo Credit: Gemini Observatory
Kalas has two photographs of the planet, taken in 2004 and 2006, that show that its movement over the 21 months fits what would be expected from a planet orbiting Fomalhaut every 872 years at a distance of 11 billion miles.
"I nearly had a heart attack at the end of May when I confirmed that Fomalhaut b orbits its parent star," Kalas said in a statement. "It's a profound and overwhelming experience to lay eyes on a planet never before seen."
None of the giant planets would be candidates to host life -- they are large and hot, like Jupiter, and orbit far away from their suns. But if large planets are there, astronomers believe at least some of the solar systems would have smaller, rocky planets like Mars or Earth that are much harder to spot.
Studying these other solar systems also could help in understanding how our own evolved.
"Fomalhaut b may actually show us what Jupiter and Saturn resembled when the solar system was about a hundred million years old," Kalas said.
The Gemini team reported in September that they had snapped the first photographs of an extrasolar planet, orbiting a star about 500 light-years from Earth.
Press release from NASA, includes additional images and animation,
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