Les Galaxies Antennes, une composite des observations d'ALMA et de Hubble
Les Galaxies Antennes (aussi connues comme NGC 4038 ou NGC 4039) sont une paire de galaxies spirales en collision à environ 70 millions d'années-lumière de nous dans la constellation du Corbeau. Cette vue combine les observations d'ALMA, faites en deux longueurs d'onde différentes durant la phase de test de l'observatoire, avec les observations du télescope spatial Hubble de la NASA/ESA en lumière visible.
L'image d'Hubbles est la vue la plus nette jamais prise de cet objet et sert de "Gold standard" pour la résolution d'une image. ALMA observe dans des longueurs d'ondes plus grandes qui fait que c'est plus dur d'obtenir des images aussi nettes. Toutefois, lorsque le réseau complet d'ALMA sera fini, il sera jusqu'à 10 fois plus nette que Hubble.
La plupart des tests d'observation d'ALMA utilisés pour faire cette image ont été faites en utilisant seulement douze antennes reliées ensemble, beaucoup mois que le nombre qui sera utilisé pour les premières observations scientifiques, beaucoup plus proches l'un de l'autre aussi. Ces deux facteurs font de cette image juste un exemple de ce qui va venir par la suite. Tandis que l'observatoire grandit, la netteté, la rapidité et la qualité des ses observations augmenteront de façon considérable lorsque de plus en plus d'antennes sont mises en service, le réseau devient ainsi plus grand. C'est toutefois la meilleure image en longueurs d'onde sub-millimétriques jamais prise des Galaxies Antenes et ouvre une nouvelle porte sur l'Univers submillimètre.
Tandis que la lumière visible, vue ici principalement en bleue, révèle les nouvelles étoiles dans les galaxies, la vue d'ALMA nous montre quelque chose qui ne peut être vu à ces longueurs d'onde: les nuages du dense gaz froid duquel les étoiles se forment. Les observations ALMA, montrées en rouge, rose et jaune, ont été faites à des longueurs d'ondes spécifiques de la lumière millimétrique et sub-millimétrique (Bande ALMA 3 et 7), faites pour détecter les molécules de monoxyde de carbone dans les, autrement, invisibles nuages d'hydrogène où les étoiles se forment.
Des concentrations massives de gaz peuvent être trouvées non seulement dans les cœurs des deux galaxies mais aussi dans la région chaotique où elles se percutent. Là, le gaz total fait des milliards de fois la masse du Soleil, un riche réservoir de matériaux pour des générations futures d'étoiles. Les observations comme celles-ci seront vitales pour nous aider à comprendre comment les collisions de galaxies peuvent déclencher la naissance de nouvelles étoile. Ceci n'est qu'un exemple de comment ALMA révèle des parties de l'Univers qui ne peuvent pas être vus avec des télescopes fonctionnant dans la lumière visible et infrarouge.
Crédit:ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope
À propos de l'image
| Identification: | eso1137a |
| Langage: | fr-ch |
| Type: | Observation |
| Date de publication: | 3 octobre 2011 11:30 |
| Communiqués de presse en rapport: | eso1137 |
| Annonces en rapport: | ann21013 |
| Taille: | 3375 x 3362 px |
À propos de l'objet
| Nom: | Antennae Galaxies, NGC 4038, NGC 4039 |
| Type: | Local Universe : Galaxy : Type : Interacting |
| Distance: | 75 million années lumière |
| Constellation: | Corvus |
Mounted Image
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Fonds d'écran
Coordinates
| Position (RA): | 12 1 52.55 |
| Position (Dec): | -18° 52' 2.96" |
Couleurs & filtres
| Domaine | Longueur d'onde | Télescope |
|---|---|---|
| Millimétrique ALMA band 3 | 2.6 mm | Atacama Large Millimeter/submillimeter Array |
| Visible V | 550 nm | Hubble Space Telescope ACS |
| Visible B | 435 nm | Hubble Space Telescope ACS |
| Infrarouge I | 814 nm | Hubble Space Telescope ACS |
| Millimétrique ALMA Band 7 | 870 μm | Atacama Large Millimeter/submillimeter Array |
| Millimétrique ALMA band 7 | 870 μm | Atacama Large Millimeter/submillimeter Array |
| Millimétrique ALMA Band 7 | 870 μm | Atacama Large Millimeter/submillimeter Array |
| Millimétrique ALMA Band 3 | 2.6 mm | Atacama Large Millimeter/submillimeter Array |
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