Une bulle cosmique géante
Avec une dimension de 300’000 années lumière, trois fois le diamètre de la Voie lactée, cette bulle colorée de gas ionisé est la plus grande jamais découverte. Cette énorme bulle contient 10 galaxies individuelles et se trouve dans une région particulièrement dense d’un groupe de galaxies appelé COSMOS_Gr30, à une distance de 6,5 milliards d’années lumière de la Terre. Choisie pour sa haute densité de galaxies, ce groupe est extrêmement varié - quelques galaxies forment activement de nouvelles étoiles alors que d’autres sont passives; certaines galaxies sont brillantes, alors que d’autres sont faibles; certaines sont massives et d’autres sont petites.
Cette bulle record a été découverte et étudiée en détail grâce à l’incroyable sensibilité de l’instrument MUSE, monté sur le Very Large Telescope d’ESO. Travaillant dans des longueurs d’onde visibles, MUSE combine les capacités d’un appareil photographique et d’un spectrographe, créant de fait un outil unique et puissant qui peut apporter un éclairage sur des objets cosmologiques qui resteraient autrement dans l’ombre.
L’oeil puissant de MUSE a permis aux astronomes de comprendre que cette grande poche de gas n’est pas primordiale, mais a été expulsée de galaxies soit durant de interactions violentes, soit par des super vents causés par des trous noirs actifs ou des supernovae. Ils ont aussi étudié comment cette magnifique bulle est devenue ionisée. On pense que le gas dans la partie supérieure (en bleu) a été ionisée par d’intense radiation électromagnétique de nouvelles étoiles et des ondes de choc qui proviennent de l’activité galactique. Les astronomes suspectent que le violent noyau actif de galaxie (en rouge) vers la bas à gauche de l’image pourrait avoir arraché les électrons de leurs atomes.
Liens
Comparaison glissante du groupe de galaxies COSMOS-Gr30 vue avec Hubble et avec MUSE
COSMOS-Gr30 vue avec le télescope spatial Hubble
Crédit:
ESO/T. Contini (IRAP, Toulouse), B. Epinat (LAM, Marseille)
À propos de l'image
| Identification: | potw1746a |
| Langage: | fr-be |
| Date de publication: | 13 novembre 2017 06:00 |
| Taille: | 1575 x 1575 px |
À propos de l'objet
| Nom: | COSMOS-Gr30 |
| Type: | Early Universe : Galaxy |
| Distance: | 6 milliard années lumière |
| Constellation: | Sextans |
Fonds d'écran
Coordinates
| Position (RA): | 10 0 35.17 |
| Position (Dec): | 2° 3' 50.22" |
| Field of view: | 0.79 x 0.79 arcminutes |
| Orientation: | North is -0.0° left of vertical |
Couleurs & filtres
| Domaine | Longueur d'onde | Télescope |
|---|---|---|
| Visible OII | 372 nm | Very Large Telescope MUSE |
| Visible V | 606 nm | Hubble Space Telescope ACS |
| Visible H-beta | 486 nm | Very Large Telescope MUSE |
| Visible I | 814 nm | Hubble Space Telescope ACS |
| Visible OIII | 500 nm | Very Large Telescope MUSE |
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