Nouvelle image de la comète ISON
Cette nouvelle vue de la comète C/2012 S1 (ISON) a été prise avec le télescope national TRAPPIST-South à l'observatoire de La Silla de l'ESO dans la matinée du vendredi 15 novembre 2013. La comète ISON a été aperçue pour la première fois dans notre ciel en septembre 2012, et fera son approche la plus proche du Soleil fin novembre 2013.
TRAPPIST-South surveille la comète ISON depuis la mi-octobre, en utilisant des filtres à large bande comme ceux utilisés dans cette image. Il utilise également des filtres spéciaux à bande étroite qui isolent l'émission de divers gaz, permettant ainsi aux astronomes de compter le nombre de molécules de chaque type qui sont libérées par la comète.
La comète ISON a été assez calme jusqu'au 1er novembre 2013, date à laquelle une première explosion a doublé la quantité de gaz émis par la comète. Le 13 novembre, juste avant la prise de cette image, une deuxième explosion géante a secoué la comète, multipliant son activité par dix. Elle est maintenant assez lumineuse pour être vue avec une bonne paire de jumelles depuis un site sombre, dans le ciel du matin vers l'Est. Au cours des deux dernières nuits, la comète s'est stabilisée à son nouveau niveau d'activité.
Ces explosions ont été causées par la chaleur intense du Soleil qui a atteint la glace dans le minuscule noyau de la comète lors de sa course effrénée vers le Soleil, provoquant la sublimation de la glace et la projection de grandes quantités de poussière et de gaz dans l'espace. Lorsque ISON s'approchera au plus près du Soleil, le 28 novembre (à seulement 1,2 million de kilomètres de sa surface, soit un peu moins que le diamètre du Soleil), la chaleur provoquera la sublimation davantage de glace. Cependant, elle pourrait aussi briser le noyau entier en petits fragments, qui s'évaporeraient complètement au moment où la comète s'éloignerait de la chaleur intense du Soleil. Si ISON survit à son passage près du Soleil, elle pourrait alors devenir spectaculairement brillante dans le ciel du matin.
L'image est un composite de quatre expositions différentes de 30 secondes à travers des filtres bleu, vert, rouge et proche infrarouge. Lorsque la comète se déplace devant les étoiles de l'arrière-plan, celles-ci apparaissent sous la forme de points colorés multiples.
TRAPPIST-South (TRAnsiting Planets and PlanetesImals Small Telescope-South) est consacré à l'étude des systèmes planétaires par deux approches : la détection et la caractérisation des planètes situées en dehors du système solaire (exoplanètes), et l'étude des comètes en orbite autour du Soleil. Le télescope national de 60 cm est opéré depuis une salle de contrôle située à Liège, en Belgique, à 12 000 km de distance.
Crédit:TRAPPIST/E. Jehin/ESO
À propos de l'image
| Identification: | potw1346a |
| Langage: | fr-ch |
| Type: | Observation |
| Date de publication: | 18 novembre 2013 11:00 |
| Taille: | 1957 x 1925 px |
À propos de l'objet
| Nom: | C/2012 S1 (ISON) |
| Type: | Solar System : Interplanetary Body : Comet |
Fonds d'écran
Couleurs & filtres
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