"NASA Discovers Planet With Four Suns"
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 October 5, 2007
How many stars does it take to "raise" a planet? In our own solar system, it took only one - our sun. However, new research from NASA's Spitzer Space Telescope shows that planets might sometimes form in systems with as many as four stars.
NASA's Spitzer Space Telescope recently discovered what might be the first planetary system with four Suns. The quadruple-star system known as HD 988000 is approximately 10-million years old, and is located 150 light-years away from Earth (fairly close in astronomical terms) in the constellation TW Hydrae.
The Spitzer's infrared spectrometer enabled astronomers to study the 'dusty disk' that revolves around a pair of stars in the quadruple-star system HD 98800 for the first time. Such 'dusty disks', formally called accretion discs, are composed of diffuse material that is set in orbital motion around a central body or bodies. These accretion discs are thought to be the birth place of planets. Instead of a smooth, continuous disk, the telescope detected gaps that could be caused by a unique gravitational relationship between the system's four stars. Alternatively, the gaps could indicate planets have already begun to form, carving out lanes in the dust.
"Planets are like cosmic vacuums. They clear up all the dirt that is in their path around the central stars," said Elise Furlan, of the NASA Astrobiology Institute at the University of California at Los Angeles. Furlan is the lead author of a paper that has been accepted for publication in The Astrophysical Journal.
Before the recent observation by Spitzer, astronomers had a rough idea of the system's structure from observations with ground-based telescopes. They knew the system contains four stars, and that the stars are paired off into doublets, or binaries. The stars in each of the binary pairs orbit around each other and the two pairs also circle each other.
Although the four stars are gravitationally bound, the distance separating the two binary pairs is about 50 astronomical units (AU) -- slightly more than the average distance between our sun and Pluto. Before Spitzer, scientists were not able to examine the accretion disc around HD 98800B closely. With Spitzer, scientists finally have a detailed view.
Story excerpted from www.tfot.info
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