An exoplanet, by definition, is any world located outside the borders of the solar system. Since the first planet of this type was discovered in 1992, the search for exoplanets has allowed to increase the hopes of finding some day extraterrestrial life. The detection of these worlds beyond the solar system remains a challenge, but a new strategy devised by researchers from the University of Geneva will allow in the future to hunt invisible exoplanets to date.The technique detects molecules that can exist in the atmosphere of the exoplanets and not in the stars that orbit
The team led by Julien H. Girard has developed a novel technique to bring to light new worlds outside the solar system through molecules that exist in its atmosphere. It is usually difficult to take direct images of the exoplanets due to the enormous contrast between the light that comes from the host star and the world revolving around it. In fact, the first time scientists managed to take a direct photograph was in 2004; On the other occasions, various methods are used to look for exoplanets that reveal their existence indirectly.
The idea of the researchers of Geneva is quite intuitive: it consists in hunting molecules that can exist in the atmosphere of these worlds and not in the stars to which they orbit. Thanks to this innovative technique, which have been released in the magazine Astronomy & Astrophysics, it has been possible to make the stars invisible and focus attention only on exoplanets. To prove that the strategy was useful, Girard's group has used archival images taken by the SINFONIinstrument, a spectrograph that began operations in 2004 at the Observatory of La Silla (Chile), within the Very Large Telescope (VLT).
The image above corresponds to several photographs of the star Beta Pictoris, located in the constellation Pictor to 70 light-years of the Earth, and the giant planet that orbits it, called beta Pictoris b — which had been discovered precisely A decade ago by the VLT. The scientists tried to hunt four different molecules — water (H2O), carbon monoxide (CO), ammonia (NH3) and methane (CH4) on the Astro and the exoplanet they used for their experiment. The first two (in blue and red) allowed to detect Beta Pictoris B, while the last two (in green and brown), not existing in their atmosphere, did not take the planet to light. In all cases, the four molecules used were not in the star, where the temperatures are high and disintegrated.
"This technique is only in its infancy," notes Jens Hoeijmakers, the first author of the study. "It should change the way the planets and their atmospheres are characterized," says the researcher. To date, direct photographs of exoplanets had been made possible by the use of instruments such as the VLT itself or the Hubble telescope. The direct observation of these distant worlds helps their characterization, although at the moment the available technology was very limited.