A Artist view of the transit of an exoplanet to its host star. The light that passes through the atmosphere is partially absorbed by the molecules present therein. By using spectroscopic methods, one can detect the absorption lines of these molecules and to deduce the chemical composition of the atmosphere. Hubble has demonstrated the presence of water molecules in five exoplanets. © Nasa
water in the atmosphere of exoplanets five Hubble confirms – 1 Photo
Wasp 17b, HD209458b, Wasp 12b, Wasp 19b and XO-1b: these are the esoteric names of exoplanets for which NASA has announced that their atmospheres contain water. Of course, for us, the water is often synonymous with life, but in this case, it was a bit difficult to understand the hype about this ad. Indeed, all these exoplanets are hot Jupiter, which means that there is no chance that we find on these stars a team carrying out a Google Street View similar sumptuous coral reefs our blue planet, as is currently the members of Catlin Seaview Survey . In addition, there are not more likely that one is in the presence of Arrakis, because every time he comes to gas giants brought to high temperatures.
Take for example the case of Wasp 12b. It orbits in just a day or almost 12 Wasp around a solar-type star located about 870 light-years away in the constellation Auriga. Discovered through superwasp (acronym for Super Wide Angle Search for Planets ) is a gas giant with a mass about 1.4 times that of Jupiter. The Spitzer infrared observations already showed the presence of a little water vapor (H 2 O), large amounts of carbon monoxide (CO) and especially methane (CH 4 ). This is an exoplanet in agony, because it is so hot it evaporates.
A video outlining the principles of detection of water in the atmosphere by Hubble five exoplanets. For a French translation fairly accurate, click on the rectangle with two horizontal bars at the bottom right. Subtitles in English should then appear if it is not already the case. By simply moving the mouse over the rectangle, you should see the word “Translate subtitles.” Click to display the menu language selection, select “French” then click “OK”. © NASA Goddard, YouTube
similar to Jupiter exoplanets exotic hot
HD209458b is probably one of the best known and most studied exoplanets. It is also known by the name of Osiris. Two times less massive than Jupiter, it turns 6.7 million kilometers of HD209458, very similar to our Sun 150 light years from Earth in just 3.5 days star. HD 209458b was spotted by the radial velocity method. But soon, astronomers noticed that its orbit led him to cross the line of sight joining us its star. During this transit global, analysis of the spectrum of light having passed through the atmosphere Exoplanet allowed to know a part of its chemical composition. We deduce that the sun must appear on a cyan background purple sky.
This is not the first time we detected water in the atmosphere of an exoplanet, but it is nevertheless significant that it is with Hubble. Since 2009, the space telescope is equipped Wide Field Camera 3 (WFC3). She observed in the near infrared, and is currently the only instrument in space capable of revealing the presence of water molecules on exoplanets.
Preview Telescope James Webb
On Earth, it is not possible to do this type of research, because the atmosphere itself contains water vapor in varying quantities. However, the WFC3 is partly a prototype for future instruments James Webb telescope which, remember, has the potential to detect biosignatures analyzing the atmospheric composition of extrasolar planets during planetary transits.
As explained by astrophysicists in several articles posted on arxiv, it is by this same method of analysis of the spectrum of light from the host star has passed through the atmosphere of an exoplanet transits when we could detect convincingly water in five exoplanets mentioned. With luck, it is therefore possible that we have indications of biosignatures with Hubble before the launch of its successor. The most amazing thing is that we find such indications for exoplanets orbiting very close stars, like Alpha Centauri or Tau Ceti.