HD 188753 Ab
HD 188753 Ab is the first known planet in a triple star system. It has been discovered by a Polish astronomer working in the United States, Dr. Maciej Konacki [1] [2]. The planet, a gas giant slightly larger than Jupiter, orbits the main star of the HD 188753 system (HD 188753A), in the constellation Cygnus. The stellar trio (yellow, orange, and red) is about 149 light-years from Earth. The planet, which is at least 14% larger than Jupiter, orbits the main star (HD 188753 A) once every 80 hours or so (3.3 days), at a distance of about 8 Gm, a twentieth of the distance between Earth and the Sun.
The other two stars whirl tightly around each other in 156 days, and circle the main star every 25.7 years at a distance from the main star that would put them between Saturn and Uranus in our own Solar System. The latter stars provoke questions regarding the leading hot Jupiter formation theory, which holds these planets form at "normal" distances and then migrate inward through some debatable mechanism. It appears as though this postulated mechanism could not have have occurred in the HS 188753 system, as any object orbiting HS 188753 A at an orbital radius greater than 1.5 AU would be unstable because of the gravitational influence of the outer star pair, although some scientists have suggested that the planet could have been formed before the triple-star system reached its current configuration.
HB 188753 Ab has been dubbed a "Tatooine planet," after a famous scene in the film Star Wars which shows two suns setting over the planet Tatooine.
References
- Template:Journal reference issue PMID 16015323
- Template:Journal reference issue PMID 16015311
External links
- "California Scientist Discovers First Extrasolar Planet Under Three Suns". Planetary Society. August 13.
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