HD 189733
HD 189733 is a yellow dwarf, which is 63 light years away. It is located in the constellation Vulpecula and is of at least one planet, HD 189733 b, orbits. The star has a surface brightness temperature of about 4680 degrees Celsius.
HD 189733 b
HD 189733 b is so far the only known planet of this system and belongs to the class of hot Jupiters. He has about 1.15 times the mass of Jupiter. The planet is only 4.7 million kilometers from its star (which only 8 percent of the distance Mercury - Sun equivalent ), which he circles in about 2.22 days. Due to the strong tidal forces of the central star HD 189733 b applies this always to the same page.
HD 189733 b is the first planet outside the solar system ( extrasolar planet ), on the water and methane - and thus an organic compound - were found. Due to the high temperature at the surface ( about 900 degrees Celsius ) is the water but in the gaseous state. About barely an exoplanet is known as much as about the gas giant HD 189733 b, which is because that the planet - as seen from Earth - regularly to its star passes by, it is to say on a so-called transiting planet in the planet. Does the light from the star on his way to Earth by the planet's atmosphere, the spectrum of the star changes corresponding to the compounds in the atmosphere of hot Jupiters. Through infrared investigation during transit less absorption was observed as expected with the Spitzer Space Telescope with an infrared band of 3.6 microns (IR spectroscopy with the IR spectrometer NICMOS, of English Near Infrared Camera and Multi- Object Spectrometer ). This behavior can only be explained by the simultaneous presence of water and methane molecules in the planet's atmosphere. The results from Spitzer were confirmed by the Hubble Space Telescope now.
On April 25th of 2012 a camera and a spectrometer aboard the Cassini spacecraft, which orbited the ringed planet Saturn, observe a passage of the exoplanet before his star. The drop in brightness of the star of about 2.5 percent was particularly well detected with the camera. However, it was not possible to obtain a spectrum of the planet's atmosphere, since this, the sensitivity of the spectrometer is not sufficient.