WASP-17 b
WASP-17 b (also spelled "WASP-17b") is an exoplanet orbiting the star WASP-17 in the constellation Scorpio . It has the lowest known density of a planet and also has a retrograde orbit. In its atmosphere is water vapor detected.
properties
The planet is probably the first to be discovered exoplanet with a retrograde , i. H. the rotation of the main star in the opposite direction of motion. In terms of diameter, WASP-17b is believed to be the largest exoplanet discovered to date and, at about six to fourteen percent the density of Jupiter , the planet with the lowest known density. The mass of the planet is about 0.5 Jupiter's masses , its radius 1.5 to 2 Jupiter radii . WASP-17b orbits its main star once every 3.7 days.
discovery
As announced on August 11, 2009, a team of astronomers - led by David Anderson, at Keele University , from the South African Astronomical Observatory - observed the gas giant , about 1,000 light years (about 306 pc ) from the Earth is away. They watched it in the years from 2006 to 2008 blackouts of starlight in passages of the planet from its main star "WASP-17" (see transit method ). Based on the characteristic red and blue shifts in the spectral lines of the main star during subsequent spectroscopic observations in the years from 2007 to 2009, the astronomers were able to infer the mass of the planet. Since it was the 17th exoplanet found so far as part of the SuperWASP project, it was given the name "WASP-17b".
See also
Web links
- Exoplanet discovered with retrograde orbit - article at Raumfahrer.net (accessed August 16, 2009)
- WASP-17 b (English) - Entry in the Extrasolar Planets Encyclopaedia (accessed August 12, 2009)
- WASP-17b: Aa Ultra-Low Density Planet in a Probable Retrograde Orbit (PDF file; 1.05 MB)
Individual evidence
- ^ NASA: Hubble Traces Subtle Signals of Water on Hazy Worlds. December 3, 2013, accessed December 7, 2013 .
- ↑ a b c New exoplanet orbits 'backwards' - article on BBC News , August 12, 2009