Capturé par un piège de poussière
Cette image d’ALMA (Atacama Large Millimeter/submillimeter Array) montre V1247 Orionis, une jeune étoile chaude entourée par un anneau dynamique de gaz et de poussière, appelé disque circumstellaire. Ce disque est visible ici en deux parties: un anneau central de matière clairement défini et une structure en forme de croissant plus délicate située vers l’extérieur.
On pense que cette région entre l’anneau et le croissant, visible comme une bande obscure, s’est formée grâce à une planète qui a creusé son sillon à travers le disque. Alors que la planète orbitant autour de son étoile, son mouvement a créé des régions de haute pression sur chaque côté de son chemin, un peu comme quand un navire crée des vagues d’étrave lorsqu’il coupe à travers l’eau. Ces régions de haute pression pourraient devenir des barrières de protection autour des sites de formation planétaire: les particules de poussière sont emprisonnées à l’intérieur pour des millions d’années, leur donnant le temps et l’espace suffisants pour s’agglomérer et croitre.
La résolution spatiale extraordinaire d’ALMA permet aux astronomes d’étudier la structure complexe d’une tel tourbillon qui piège la poussière pour la première fois. Cette image révèle non seulement la forme en croissant du piège de poussière à l’extérieur de la bande obscure, mais aussi les régions d’excès de poussière à l’intérieur de l’anneau, qui peut-être indique un deuxième piège qui s’est formé à l’intérieur de l’orbite de la potentielle planète. Cela confirme les prédictions précédentes de simulations par ordinateur.
La capture de la poussière est une solution potentielle à un problème majeur dans la théorie actuelle de la formation des planètes, qui prédit que les particules devraient fluire (“drift”) vers l’étoile centrale et être détruite avant qu’elle n’aient eu le temps de croitre jusqu’à une dimension planétésimale (le problème du “drift” radial en anglais).
Crédit:
ALMA (ESO/NAOJ/NRAO)/S. Kraus (University of Exeter, UK)
À propos de l'image
| Identification: | potw1742a |
| Langage: | fr |
| Type: | Observation |
| Date de publication: | 16 octobre 2017 06:00 |
| Taille: | 2000 x 2000 px |
À propos de l'objet
| Nom: | V1247 Orionis |
| Type: | Milky Way : Star : Circumstellar Material : Disk : Protoplanetary |
| Constellation: | Orion |
Fonds d'écran
Coordinates
| Position (RA): | 5 38 5.25 |
| Position (Dec): | -1° 15' 21.70" |
| Field of view: | 0.03 x 0.03 arcminutes |
| Orientation: | North is -0.0° left of vertical |
Couleurs & filtres
| Domaine | Longueur d'onde | Télescope |
|---|---|---|
| Millimétrique H | 870 μm | Atacama Large Millimeter/submillimeter Array Band 7 |
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