Pressemeddelelse

Hvad er et navn? En smuk kosmisk rose, hvordan den end kaldes

23. september 2015

Det rosenfarvede område Messier 17, hvor der foregår intens stjernedannelse, er hovedpersonen i dette nye billede fra Wide Field Imager på MPG/ESO 2,2 m teleskopet på ESOs La Sillaobservatorium i Chile. Billedet viser hele tågen, og alligevel er det et af de klareste billeder nogensinde med mange fine detaljer i det kosmiske landskab af interstellare gasser, støv og nyfødte stjerner

Tågen har fået mange navne igennem tiden, også flere end alle andre af denne type. Officielt kaldes den Messier 17, men blandt kælenavnene er Omega Nebula, Svanetågen, Fluebenet (Checkmark Nebula), Hesteskotågen og, for også at glæde dem, med maritime interesser, Hummertågen.

Messier 17 befinder sig omkring 5 500 lysår fra Jorden (lidt udenfor Verona!), nær Mælkevejens plan, og i retning af stjernebilledet Skytten (Sagittarius). Tågen fylder en del på himlen - diameteren er omkring 15 lysår. Stoffet i tågen danner nye stjerner, og i billedfeltet er der også masser af stjerner både foran og bagved Messier 17.

I tågen er der en ret kompleks rød struktur med toner af pink. Farverne er et sikkert tegn på lysende hydrogengas. De unge, kortlivede blå stjerner, som for nyligt er dannet i Messier 17, udsender nok ultraviolet lys til at opvarme den omgivende gas så meget, at den begynder at lyse klart. I centralområderne er farverne lysere, og nogle områder er helt hvide. Den hvide farve er ægte nok - den skyldes blandingen af lyset fra de varmeste gasarter med det stjernelys, som tilbagekastes fra støvet.

Vi anslår, at gassen i tågen i alt vejer mere end 30 000 gange Solens masse. I tågen er der også en åben stjernehob med ikke blot 2 klare stjerner som øjne, men hele 35 stjerner. Den kaldes NGC 6618[1]. Det samlede antal stjerner i tågen er meget større. Bare i centralområdet er der næsten 800, og der dannes flere hele tiden i de ydre områder.

Med baggrund i dette rosa skær, så fint som Julies kinder, er der et netværk af mørkere støvområder, som spærrer for baggrundsskæret. På dette billede, taget i synligt lys, er støvbåndene mørke, men fotograferet med infrarødfølsomme kameraer lyser også de klart op.

Det officielle navn på tågen stammer fra den franske kometjæger Charles Messier, som tog denne tåge med som nummer sytten i sit berømte astronomiske katalog i 1764[2]. Selv om den kun var kendt under det kedelige navn Messier 17, spørger vi med Shakespeare (næsten): Hvad er et navn? En rose er dog lige smuk hvad end den kaldes!

Billedet stammer fra ESOs Cosmic Gems program[3].

Noter

[1] Denne betegnelse bruges undertiden for hele den stjernedannende region.

[2] Det var astronomen Jean Philippe de Chéseaux, som opdagede objektet i 1745, men den opdagelse vandt ikke stor udbredelse. Derfor ser det ud til, at Messier uafhængigt har opdaget tågen, og har taget den med i sit katalog næsten 20 år senere.

[3] ESO Cosmic Gems programmet er et formidlingsprojekt, med det formål at producere billeder af interessante, spndende eller blot flotte himmelobjekter med ESOs teleskoper, til glæde for offentligheden og uddannelsessektoren. Der bruges teleskoptid, som alligevel ikke kunne bruges til videnskabelige formål. Nogle af billederne kan dog måske alligevel bruges videnskabeligt, og de er tilgængelige for astronomerne i ESOs videnskabsarkiv.

Mere information

ESO er den fremmeste fællesnationale astronomiorganisation i Europa, og verdens langt mest produktive jordbaserede astronomiske observatorium. 16 lande er med i ESO: Belgien, Brazilien, Danmark, Finland, Frankrig, Italien, Nederlandene, Polen, Portugal, Spanien, Sverige, Schweiz, Storbritannien, Tjekkiet, Tyskland og Østrig, og desuden værtsnationen Chile. ESO har et ambitiøst program, som gør det muligt for astronomer at gøre vigtige videnskabelige opdagelser. Programmet har focus på design, konstruktion og drift af stærke jordbaserede observatorier. Desuden har ESO en ledende rolle i formidling og organisering af samarbejde omkring astronomisk forskning. ESO driver tre enestående observatorier i verdensklasse i Chile: La Silla, Paranal og Chajnantor. På Paranal driver ESO VLT, Very Large Telescope, som er verdens mest avancerede observatorium for synligt lys, samt to oversigtsteleskoper. VISTA, som observerer i infrarødt, er verdens største oversigtsteleskop, og VLT Survey Teleskopet er det største teleskop bygget til at overvåge himlen i synligt lys. ESO er en af de største partnere i ALMA, som er det største eksisterende astronomiprojekt. For tiden bygges E-ELT, et 39 m optisk og nærinfrarødt teleskop på Cerro Armazones, tæt ved Paranal. Det bliver "verdens største himmeløje".

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Kontakter

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
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E-mail: rhook@eso.org

Ole J. Knudsen (Pressekontakt Danmark)
ESOs formidlingsnetværk og Aarhus Space Centre, Aarhus Universitet
Aarhus, Danmark
Tel: +45 8715 5597
E-mail: eson-denmark@eso.org

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Dette er en oversættelse af ESO pressemeddelelse eso1537 lavet af ESON - et netværk af personer i ESOs medlemslande, der er kontaktpunkter for medierne i forbindelse med ESO nyheder, pressemeddelelser mm.

Om pressemeddelelsen

Pressemeddelelse nr.:eso1537da
Navn:M 17, Messier 17, Omega Nebula, Swan Nebula
Type:Milky Way : Nebula : Appearance : Emission : H II Region
Facility:MPG/ESO 2.2-metre telescope
Instruments:WFI

Billeder

Stjernedannelse i Messier 17
Stjernedannelse i Messier 17
Tågen Messier 17 i stjernebilledet Skytten
Tågen Messier 17 i stjernebilledet Skytten
Digitized Sky Survey billede af Omegatågen (M 17)
Digitized Sky Survey billede af Omegatågen (M 17)

Videoer

Zoom ind på stjernedannelsen i Messier 17
Zoom ind på stjernedannelsen i Messier 17
Et tæt kig på tågen Messier 17
Et tæt kig på tågen Messier 17

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