Superbe time-lapse d’une exoplanète
Le très grand télescope (VLT) d'ESO a capturé une série d'images sans précédent montrant le passage de l'exoplanète Beta Pictoris b autour de son étoile parente. Cette jeune exoplanète massive a été découverte en 2008 grâce à l’instrument NACO du VLT. La même équipe scientifique a depuis suivi l’exoplanète de fin 2014 à fin 2016, à l’aide de l’instrument de recherche SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), un autre instrument du VLT. Beta Pictoris b est alors passé si près du halo de l’étoile qu’aucun instrument ne pouvait les distinguer l'une de l'autre. Près de deux ans plus tard, après semblé s’être fondue dans l’image de l’étoile, Beta Pictoris b a maintenant émergé du halo. Cette réapparition a été capturée à nouveau par SPHERE.
La série complète d'images, avec la lueur brillante de l'étoile Beta Pictoris masquée, a été compilée pour créer un time-lapse étonnant et unique de l'orbite à longue période de Beta Pictoris b. SPHERE a aperçu Beta Pictoris b en le photographiant directement - et non en déduisant indirectement son existence. La plupart des exoplanètes connues ont été découvertes en utilisant des méthodes indirectes - observant comment elles affectent la position ou la luminosité d'une étoile. SPHERE de l’ESO est spécialisé dans une méthode appelée imagerie directe, qui recherche les exoplanètes en les photographiant directement. Cette recherche extraordinairement stimulante nous fournit des images claires de mondes lointains tels que Beta Pictoris b, à 63 années-lumière.
Beta Pictoris orbite son étoile à une distance similaire à celle qui sépare le Soleil et Saturne, environ 1,3 milliard de kilomètres, ce qui en fait l’exoplanète la plus proche de son étoile à avoir été photographiée directement. La surface de cette jeune planète est encore chaude, aux alentours de 1’500 °C, et la lumière qu’elle émet a permis à SPHERE de la découvrir et de suivre son orbite, en la voyant émerger de son passage devant son étoile mère. Alors qu'un coup d'œil sur ces images pourrait suggérer que la planète passe devant l'étoile en éclipsant un peu de sa lumière, Beta Pictoris b en fait ne transite pas vraiment. Ces images constituent une réalisation remarquable et annoncent une nouvelle ère dans l’un des domaines les plus passionnants et stimulants de l’astronomie - la découverte et la caractérisation d’exoplanètes.
Crédit:ESO/Lagrange/SPHERE consortium.
À propos de l'image
| Identification: | potw1846a |
| Langage: | fr |
| Type: | Collage |
| Date de publication: | 12 novembre 2018 06:00 |
| Taille: | 2628 x 1950 px |
À propos de l'objet
| Nom: | Beta Pictoris b |
| Type: | Milky Way : Star : Circumstellar Material : Planetary System |
| Distance: | 65 années lumière |
Fonds d'écran
Couleurs & filtres
| Domaine | Longueur d'onde | Télescope |
|---|---|---|
| Infrarouge K | 2.11 μm | Very Large Telescope SPHERE |
| Infrarouge H | 1.593 μm | Very Large Telescope SPHERE |
| Infrarouge K | 2.251 μm | Very Large Telescope SPHERE |
| Infrarouge H | 1.667 μm | Very Large Telescope SPHERE |
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