Exoplanets

SHOTLIST: SOURCE: AFP VIDEOGRAPHICS IMAGES: 01:22 -Zoom out from the sun to planets of the solar system-Diagram of a black exoplanet in the yellow sky-Zoom in on Exoplanet diagram-Diagram of a sky filled with glittering planets, zoom out-Close-up on different types of exoplanets -Close-up on a luminous star of an exoplanet-Gravitational effect -Micro eclipse on the exoplanet star-Diagram of an exoplanet -Zoom in on the solar system AFP TEXTSeptember 16, 2020 Astronomers have discovered a planet the size of Jupiter closely orbiting the smouldering remains of a dead star, the first time that an intact exoplanet has been discovered travelling around a white dwarf, according to research published Wednesday. Researchers said the fate of this giant planet, called WD 1586 b, offers a potential vision of our own Solar System when the Sun eventually ages into a white dwarf in around five billion years. When it has burned through its stores of hydrogen, a star like the Sun enters its death-throes, first swelling enormously into an incandescent red giant that scorches and engulfs nearby planets. Then it collapses, reducing it to its burnt-out core. This is the white dwarf, an extremely dense stellar ember glowing faintly with leftover thermal energy and slowly fading over billions of years. Previous research has suggested some white dwarfs can retain more distant remnants of their planetary systems. But until now no intact planets had been detected in orbit around one of the dead stars...(continues) SCRIPT EN: Until the late 20th century, astronomers had only identified the planets in our own solar system.But everything changed in 1995, when the discovery of the first exoplanet orbiting a Sun-like star was confirmed.Known as 51 Pegasi b, this giant ball of gas is similar to Jupiter and marked a major scientific breakthrough.Twenty years later, around 2,000 exoplanets have been confirmed….and hundreds of billions more are believed to exist in the universe.Astronomers found the largest planets first, because they were the easiest to detect. These were followed by mini-Neptunes, made of hydrogen and helium. Planets covered with oceans of lava or ice. And even little rocks like Earth. It’s extremely difficult to catch a direct glimpse of an exoplanet, because their parent stars are much brighter, blocking them out. They are generally detected indirectly:-Either by observing the gravitational effect the planet exerts on its star-Or by studying the slight dip in light or micro-eclipses caused by the planet as it orbits its star. Technological advances have enabled a small number to be photographed with the aim of learning more about the origins of our solar system. Is Earth unique…or does life exist elsewhere?Sources: NASA, ESA SCRIPT FR: Jusqu’à la fin du XXe siècle, les astronomes n’avaient identifié que les planètes du système Solaire. Ce n'est qu'en 1995 qu'est découverte et confirmée la première exoplanète… orbitant donc autour d'une autre étoile que le Soleil.51 Pegasi b, géante gazeuse comparable à Jupiter, bouleverse les théories scientifiques.20 ans plus tard, environ 2.000 exoplanètes sont recensées. Nombre estimé dans l'univers : des centaines de milliards.Les astronomes trouvent d’abord des planètes géantes, plus faciles à détecter. Puis des mini-neptunes faites d'hydrogène et d'hélium. Des planètes couvertes d'océans, de lave ou de glace... Et même des petites rocheuses comme la Terre.Il est très difficile de capter la lueur directe des exoplanètes, car leurs étoiles, bien plus lumineuses, nous éblouissent. On les détecte surtout indirectement. - Soit en observant l’effet gravitationnel que la planète exerce sur son astre.- Soit en étudiant la légère baisse de luminosité, ou micro-éclipse, qu’elle provoque en passant devant son étoile.Avec l'amélioration des moyens techniques, une poignée a pu être photographiée.Objectif: cerner les origines de notre propre système solaire. Et surtout, savoir si notre Terre est unique, ou si la vie peut exister ailleurs...Edition : Elia VaissièreSources : CNRS, NASA, exoplanet.eu