Friday, July 15, 2005

Planet Found in Triple-Star System

This item caught my attention. Scientists have found a planet stably orbiting in a triple star system 149 light years from Earth:

Discovery of a First: A World With 3 Suns

The planet orbits the main star with a period of 3.35 days (distance from star: 4.5% Earth-Sun distance), while the other two stars orbit a common center of mass that orbits the main star every 25 years (elliptical orbit with average distance from main star: 12.3 times Earth-Sun distance). The planet is a Jupiter-like gas giant. (Helpful orbital diagram)

Here's an animation of what you'd see standing on a moon of the planet: [Quicktime]

What's the import?

But the paired companion stars to HD 188753's primary star, scientists now realize, would presumably have burned away the disk of gas and dust out of which a planet could have formed. According to the standard orbital migration model, the newfound planet should not exist.

Oh well. Back to the drawing board....

John Noble Wilford, "Discovery of a First: A World With 3 Suns" New York Times (July 15, 2005).

Mark Peplow, "The triple sunset that should not exist," Nature (online: 13 July 2005).

Maciej Konacki, "An extrasolar giant planet in a close triple-star system," Nature 436 (14 July 2005), 230-233.

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