Un peso massimo intergalattico
Questa immagine di campo profondo mostra un cosiddetto superammasso di galassie - un enorme complesso di ammassi di galassie tra di loro legati. Questo superammasso, noto come Abell 901/902, comprende tre ammassi principali ed un certo numero di filamenti galattici, tipici di tali super-strutture. Uno degli ammassi, Abell 901a, può essere individuato sopra ed appena a destra della prominente stella rossa vicina al centro dell'immagine. Un secondo, Abell 901b, si trova a destra di Abell 901a e leggermente più in basso. Infine, l'ammasso Abell 902 è visibile direttamente sotto la stella rossa, verso il bordo inferiore dell'immagine.
Il superammasso Abell 901/902 si trova ad oltre due miliardi di anni luce dalla Terra e contiene centinaia di galassie in una regione di circa 16 milioni di anni luce. Per confronto, il Gruppo Locale di galassie - che contiene la nostra Via Lattea insieme ad altre 50 galassie - misura approssimativamente 10 milioni di anni luce.
Questa immagine è stata ottenuta dallo strumento Wide Field Imager (WFI) sul telescopio da 2,2 metri dell'MPG/ESO, situato all'osservatorio di La Silla, in Cile. Usando le informazioni ottenute dal WFI e dall'Hubble Space Telescope della NASA/ESA, nel 2008 gli astronomi sono riusciti a tracciare una mappa della distribuzione di materia oscura all'interno del superammasso, mostrando che gli ammassi e le galassie singole contenuti nella super-struttura sono contenuti da vasti grumi di materia oscura. Per far ciò, gli astronomi hanno osservato il modo in cui la luce proveniente da 60 mila galassie lontane, situate dietro il superammasso, viene distorta dall'effetto gravitazionale della materia oscura, rivelandone quindi la distribuzione. Si stima che la massa dei quattro principali aggregati di materia oscura in Abell 901/902 sia circa 10 bilioni di volte quella del Sole.
Le osservazioni qui mostrate fanno parte del progetto COMBO-17, una survey del cielo realizzata usando lo strumento WFI con 17 diversi filtri ottici. Finora il progetto COMBO-17 ha individuato più di 25 mila galassie.
Links
- La survey COMBO-17 al Max-Planck-Institut für Astronomie, Heidelberg
- Panoramica ampia dell'area intorno al superammasso Abell 901/902
ESO
Riguardo l'immagine
| Identificazione: | potw1304a |
| Lingua: | it-ch |
| Tipo: | Osservazione |
| Data di rilascio: | Lunedì 28 Gennaio 2013 10:00 |
| Grandezza: | 7595 x 7557 px |
Riguardo all'oggetto
| Nome: | NAME ACO 901-902 SUPERCLUSTER |
| Tipo: | Early Universe : Galaxy : Grouping : Supercluster |
| Distanza: | z=0.16 (spostamento del rosso) |
| Constellation: | Sextans |
Formati delle immagini
Coordinate
| Position (RA): | 9 56 17.78 |
| Position (Dec): | -10° 1' 27.67" |
| Field of view: | 30.12 x 29.97 arcminutes |
| Orientazione: | Il Nord è a 0.1° a destra della verticale |
Colori e filtri
| Banda | Lunghezza d'onda | Telescopio |
|---|---|---|
| Ultravioletto U | 340 nm | MPG/ESO 2.2-metre telescope WFI |
| Ottico B | 451 nm | MPG/ESO 2.2-metre telescope WFI |
| Ottico V | 539 nm | MPG/ESO 2.2-metre telescope WFI |
| Ottico R | 651 nm | MPG/ESO 2.2-metre telescope WFI |
| Infrarosso I | 783 nm | MPG/ESO 2.2-metre telescope WFI |
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