WASP-17 b

WASP -17 b (also written " WASP - 17b ") is an exoplanet orbiting the star WASP -17 in the constellation Scorpio. He has been the lowest known density of a planet and also a decline (retrograde ) orbit. In its atmosphere water vapor was detected.

Properties

When the planet is probably the first exoplanets, declining, ie the rotation of the main star opposite direction of movement. Presumably, WASP - 17b in terms of its diameter the largest exoplanet discovered to date and, at about six to fourteen percent of the density of Jupiter, the planet with the lowest known density. The mass of the planet is about 0.5 times Jupiter's mass, its radius is 1.5 to 2 Jupiter radii. WASP - 17b orbits its main star approximately every 3.7 days once.

Discovery

As announced on 11 August 2009, watching a team of astronomers - under the direction of David Anderson, at Keele University, the South African Astronomical Observatory of - the gas giant, the (about 306 pc) of about 1,000 light- years of earth is removed. They observed in the years 2006-2008 the obscuration of the starlight at crossings of the planet from its main star " WASP -17". Based on the characteristic red and blue shifts in the spectral lines of the main star in subsequent spectroscopic observations in the years 2007-2009, the astronomers were able to infer the mass of the planet. Since it was the 17th so far through the SuperWASP project exoplanets found, he was given the name " WASP - 17b ".