User:Kepler-1229b/sandbox/HD 188753 Ab

HD 188753 Ab is a disproven extrasolar planet approximately 149 light-years away in the constellation of Cygnus (the Swan). The planet was announced in 2005 to be orbiting the primary star in the HD 188753 system, which is a trinary star system. Further attempts to confirm the discovery, however, failed. In 2007, the planet was retracted (due to lack of evidence). Because the planet orbited in a multiple star system, the planet was nicknamed the "Tatooine Planet", in reference to the multiple suns of Luke Skywalker's homeworld in the Star Wars movies.

Detection and discovery
HD 188753 Ab was announced in July of 2005, by Polish-American astronomer Maciej Konacki. The planet was classified as a hot Jupiter that was slightly more massive than Jupiter. The planet was announced to be orbiting the primary star of the HD 188753 system (which is a Solar twin, yellow dwarf star), with two other stars (an orange dwarf and a red dwarf) approximately 12 astronomical units away. HD 188753 Ab was claimed to be at least 14% more massive than Jupiter, orbiting its sun once every 80 hours or 3 days, at a distance of about 0.0446 astronomical units (a twentieth of the distance between the Earth and the Sun).

HD 188753 Ab was claimed to be the first known extrasolar planet in a triple star system. However, an attempt to confirm the discovery failed. In 2007, a team at the Geneva Observatory concluded that the claimed planet does not, in fact, exist. Konacki issued a response to this, claiming that the precision of the follow-up measurements was not in fact sufficient to confirm or deny the planet's existence. Further observations of this system are planned over the course of 2007.

Physical characteristics
The existence of HD 188753 Ab (a hot Jupiter) in a relatively close trinary star system has challenged astronomers in the formation models of planets. The current idea is that giant planets form in the outer reaches of their system (in similar orbits as Jupiter and Saturn). Once formed, some of these planets may migrate close to their stars, becoming hot Jupiters. The issue with HD 188753 Ab is that any protoplanetary disk would have been ended around 1 astronomical unit from the primary star (due to the presence of the secondary stars). A Jovian planet should not have been able to form so close to the primary, and with no disk material beyond 1 AU, a planet should not have been able to form beyond that distance to migrate inward. One of the possibilities suggested that the planet formed before the secondary stars had reached their current configuration. This suggests that the two secondary stars were once more distant than they are now.