Observation made last night of the transit of exoplanet HD189733 b.
HD 189733, or HD 189733 A, is an orange dwarf about 63 light-years from Earth. One extrasolar planet is known around this star, designated HD 189733b. Thanks to its orbit and its large size relative to its star, HD 189733b is the easiest transiting extrasolar planet to observe and study: its eclipse depth is 0.028 magnitudes, a brightness drop of almost 3%.
An international group of scientists, including Spanish researchers, has detected water vapor in its atmosphere. It is a gas giant with about 1.15 times Jupiter's mass, and the eclipse lasts 109 minutes. It orbits the star every 2.2 days, lying only 4.5 million km away. The atmospheric temperature of HD 189733b is about 700 degrees Celsius or higher, so the large amount of water vapor in its atmosphere cannot condense to fall as rain or form clouds.
