Washington, Nov 14 : Astronomers have obtained the first-ever direct images identifying a multi-planet system around a normal star.
The images were obtained using the Gemini North telescope and W.M. Keck Observatory on Hawaii's Mauna Kea.
The Gemini images had allowed the international team to make the initial discovery of two of the planets in the confirmed planetary system with data obtained on October 17, 2007.
Then, on October 25, 2007, and in the summer of 2008, the team, led by Christian Marois of the National Research Council of Canada's Herzberg Institute of Astrophysics and members from the U.S. and U.K., confirmed this discovery and found a third planet orbiting even closer to the star with images obtained at the Keck II telescope.
In both cases, adaptive optics technology was used to correct in real-time for atmospheric turbulence to obtain these historic infrared images of an extra-solar multiple-planet system.
According Dr. Marois, this discovery is the first time that a family of planets around a normal star outside of our solar system has been directly imaged.
"Until now, when astronomers discover new planets around a star, all we see are wiggly lines on a graph of the star's velocity or brightness," said team member Bruce Macintosh of the Lawrence Livermore National Laboratories.
"Now we have an actual picture showing the planets themselves, and that makes things very interesting," he added.
The host star, a young, massive star called HR 8799, is about 130 light years away from Earth.
Comparison of multi-epoch data has shown that the three planets are all moving with, and orbiting around, the star, proving that they are associated with it rather than just being unrelated background objects coincidentally aligned in the image.
The planets, which formed about sixty million years ago, are young enough that they are still glowing from heat released as they contracted.
Analysis of the brightness and colors of the objects (at multiple wavelengths) shows that these objects are about seven and ten times the mass of Jupiter.
As in our solar system, these giant planets orbit in the outer regions of this system - at roughly 25, 40, and 70 times the Earth-Sun separation.
The furthest planet orbits just inside a disk of dusty debris, similar to that produced by the comets of the Kuiper Belt objects of our solar system.
In some ways, this planetary system seems to be a scaled-up version of our solar system orbiting a larger and brighter star.
According to Dr. Macintosh, "After all these years, it's amazing to have a picture showing not one but three planets. The discovery of the HR 8799 system is a crucial step on the road to the ultimate detection of another Earth."