Messier 87 set med ESOs Very Large Telescope
Messier 87, eller M87 er en enorm elliptisk galakse, som befinder sig omkring 55 millioner lysår fra Jorden, i retning af stjernebilledet Jomfruen. Den blev opdaget i 1781 af Charles Messier, med det er først i det 20. århundrede, at astronomerne er blevet klar over, at det er en galakse. Den vejer det dobbelte af vores egen galakse Mælkevejen, og den indeholder i størrelsesordenen af ti gange flere stjerner. Det er en af de største galakser i det lokale Univers. Ud over selve den enorme størrelse, er der andre enestående træk ved M87. For eksempel indeholder den usædvanligt mange kugleformede stjernehobe: Mælkevejen har under 200, men M87 har omkring 12 000 - et antal, som nogle forskere mener er indhøstet fra en sværm af mindre nabogalakser.
Som alle andre store galakser har M87 et supertungt sort hul i centrum. Massen af det sorte hul i midten af en galakse afhænger af hele galaksens masse, så det ville ikke overraske, om det sorte hul i M87 er et af de største og tungeste, vi kender. Tilstedeværelsen af det sorte hul forklarer måske også en af de meget energirige egenskaber ved denne galakse: den har en relativistisk jet af stof, som udsendes fra den næsten med lysets hastighed.
Lige netop dette sorte hul er valgt til at blive det første, som skulle observeres med Event Horizon Telescope. Det skyldes to ting. Opløsningsevnen for EHT er utrolig, men der er dog en grænse. Jo større et sort hul er, des større er også dets diameter, så det centrale sorte hul i M87 er et usædvanligt godt mål alene af den grund, også i sammenligning med mindre sorte huller tættere på. Den anden grund er mere lokal. M87 befinder sig set fra Jorden forholdsvis tæt på himlens ækvator, så den er synlig fra både den sydlige og den nordlige halvkugle af Jorden. Dermed har så mange teleskoper som muligt i EHT-samarbejdet kunnet observere den i stor afstand fra hinanden, og det forøger opløsningen i det endelige billede.
Billedet her er optaget med instrumentet FORS2 på ESOs Very Large Telescope i forbindelse med observationprogrammet Cosmic Gems. ESOs teleskoper bliver brugt til at skabe billeder af interessante, spændende eller bare flotte himmelobjekter til glæde primært for uddannelsessektoren og almindelig formidling. Der bruges teleskoptid, som af forskellige grunde ikke kan anvendes til videnskabeligt arbejde, og resultaterne er nogle af de mest fantastiske objekter på nattehimlen. For det tilfælde, at de indhøstede data alligevel en gang kunne bruges også til videnskabelige formål, så gemmes alle observationer i ESO Science Archive, hvor forskerne kan få adgang til dem.
Kilde:ESO
Om billedet
| Id: | eso1907b |
| Sprog: | da |
| Type: | Observation |
| Udgivelsesdato: | 10. april 2019 15:07 |
| Relaterede pressemeddelelser: | eso2305, eso2105, eso1907 |
| Størrelse: | 1646 x 1666 px |
Om objektet
| Navn: | Messier 87 |
| Type: | Local Universe : Galaxy : Component : Central Black Hole |
| Constellation: | Virgo |
Baggrundsbilleder
Koordinater
| Position (RA): | 12 30 49.29 |
| Position (Dec): | 12° 23' 29.38" |
| Field of view: | 6.92 x 7.00 arcminutes |
| Orientering: | Nord er -0.0° venstre fra lodret |
Farver & filtre
| Bånd | Bølgelængde | Teleskop |
|---|---|---|
| Optisk b | 440 nm | Very Large Telescope FORS2 |
| Optisk v | 557 nm | Very Large Telescope FORS2 |
| Optisk R | 655 nm | Very Large Telescope FORS2 |
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