Structure et mouvement de l'atmosphère de l'exoplanète Tylos
Ce diagramme montre la structure et le mouvement de l'atmosphère de l'exoplanète Tylos (WASP-121b). L'exoplanète est représentée de haut sur cette figure, en regardant l'un de ses pôles. La planète tourne dans le sens inverse des aiguilles d'une montre, de telle sorte qu'elle présente toujours le même côté à son étoile parente. Il fait donc toujours jour sur une moitié de la planète et nuit sur l'autre. La transition entre la nuit et le jour est le « côté matin », tandis que le « côté soir » représente la transition entre le jour et la nuit ; son côté matin est à droite et son côté soir à gauche.
Lorsque la planète passe devant son étoile hôte, les atomes de l'atmosphère de la planète absorbent des couleurs ou des longueurs d'onde spécifiques de la lumière de l'étoile, qui peuvent être mesurées à l'aide d'un spectrographe. À partir de ces données, obtenues dans ce cas avec l'instrument ESPRESSO du Very Large Telescope de l'ESO, les astronomes peuvent reconstituer la composition et la vitesse des différentes couches de l'atmosphère.
La couche la plus profonde est un vent de fer qui s’éloigne du point de la planète où l’étoile est directement au-dessus. Au-dessus de cette couche, un jet très rapide de sodium se déplace plus vite que la rotation de la planète. Ce jet s’accélère même lorsqu’il passe du côté du matin au côté du soir de la planète. Enfin, une couche supérieure de vent d’hydrogène souffle vers l’extérieur. Cette couche d’hydrogène chevauche le jet de sodium en dessous.
Crédit:
ESO/M. Kornmesser
À propos de l'image
| Identification: | eso2504c |
| Langage: | fr-ch |
| Type: | Dessin |
| Date de publication: | 18 février 2025 17:00 |
| Communiqués de presse en rapport: | eso2504 |
| Taille: | 4412 x 3000 px |
À propos de l'objet
| Nom: | WASP-121 b |
| Type: | Milky Way : Star : Circumstellar Material : Planetary System |
Image Formats
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