Thursday , December 9 2021

Research: exoplanet inflated like a balloon –


Although helium is a rare element on Earth, is everywhere in the Universe. It is, after hydrogen, the major component of the stars and planets gaseous giants. Despite its abundance, helium was recently observed only in the atmosphere & # 39; gaseous giant international team including astronomers from the University & # 39; Geneva (UNIGE), Switzerland. The team, this time led by the Geneva researchers, observed in detail and for the first time ex this gas heated atmosphere over a & # 39; exoplanet, blown b & # 39; literal way with -elju. The results are published in science.

Helium is the second most abundant element in the Universe. Projected 2000 as one of the best possible traces of the atmospheres of exoplanets, orbiting these planets around stars other than the sun, took 18 astronomer to actually identify it. It was difficult to spot because of the signature & # 39; very particular observation & # 39; helium, contained in the infrared, out of range for most & # 39; the instruments used before. The discovery took place early this year, thanks to the observations of the Space Telescope & # 39; Hubble, which proved difficult to interpret. Team members from UNIGE, members of the National Center for Competence in Research Planet, had the idea to indicate another telescope equipped with a new instrument – called spettrografija Carmenes.

The discovery of planets with colors & # 39; Carmenes

Spectrographs decomposes light of & # 39; star into its component colors, like a rainbow. The "resolution" of & # 39; spettrografija is a measure that indicates the number of & # 39; colors that can be disclosed. While the human eye can not distinguish any color beyond the red without proper camera, infrared eye & # 39; you & # 39 Hubble; identify hundreds & # 39; colors there. That was enough to identify the colored signature & # 39; helium. The Carmenes device, installed on the telescope & # 39; 4 meters at the observatory & # 39; Calar Alto in & # 39; Andaluċja, Spain, is able to identify more than 100 & # 39; 000 color infrared!

This high spectral resolution enabled the team to detect the position and speed of & # 39; atoms & # 39; helium in the atmosphere of & # 39; on & # 39; exoplaneta of gaseous & # 39; as Neptun, 4 times larger than Earth. Located in the constellation Cygnus (Switzerland), 124 light years from home, HAT-P-11b is a "hot Neptune" (decent 550 ° C!), Twenty times closer to its star than the Earth is on the South sun. "We suspect that this proximity to & # 39; the can star & # 39; impact on the atmosphere & # 39; this exoplanet" says Romain Allart, a student of PhD in & # 39; UNIGE and first author & # 39; the study. "The new observations are so precise that the atmosphere & # 39; the exoplanet is no doubt blown by stellar radiation escapes to space", he adds.

Planet inflated with helium

These observations are supported by numerical simulation, led by Vincent Bourrier, co-author of the study and a member of the European project * FOUR ACES. Thanks to the simulation, it is possible to follow the trajectory of & # 39; atoms & # 39; helium "helium is blown from the planet for his side at night & # 39; more than 10,000 km per hour", explains Vincent Bourrier. "Because it is a light gas like this, escape easily from Earth and forms a cloud attraction extended all around." This gives HAT-P-11b form & # 39; bubble & # 39; blown hell.

This result opens a new window to observe the prevailing extreme weather conditions in hot exoplanets. The comments & # 39; Karmes show that such studies have been designed to be feasible only from space, can be obtained by & # 39; more precision than terrestrial telescopes equipped with the right kind of & # 39; instruments. "These are exciting times for search & # 39; & # 39 atmospheric signatures in; exoplanets", says Christophe Lovis, senior lecturer at the UNIGE and co-author of the study. In fact, the UNIGE astronomers are also involved with & # 39; a powerful way in the design and exploitation of & # 39; two spettrografiċi of infrared b & # 39; high-resolution, similar to Carmenes. One of them, called SPIRou, has just begun campaign & # 39; observation from Hawaii, while the Department of Astronomy of the UNIGE host the first of Search Planet Infrared Near tests (NIRPS) to be installed in -Ċili at the end of 2019. result will strengthen the scientific community interest in these instruments. Their number and their geographical distribution enable us to cover the entire sky, in search for evaporation & # 39; exoplanets ", concludes Lovis.

* FOUR ACES, Future of Upper Atmospheric Characterization of exoplanet With Spectroscopy, is a project funded by a grant consolidators of the European Research Council (ERC) under the Program for Research and the 2020 European Union Innovation (agreements & # 39; grant No. 724 427).


University & # 39; Geneva. .

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