Pressmeddelande
Vintergatans släkting – en galax som vår, sedd från sidan
2 september 2009
Europeiska sydobservatoriet, ESO, har släppt en dramatisk ny bild på en närliggande galax som astronomer tror liknar vår egen, Vintergatan.
Galaxen, som har katalognamnet NGC 4945, är som Vintergatan en spiral med armar som lyser av hundratals miljoner stjärnor. Men NGC 4945 skiner starkare i mitten och härbärgerar sannolikt ett supertungt svart hål som slukar materia och skickar gigantiska mängder av energi ut i rymden.
NGC 4945 ligger bara 13 miljoner ljusår bort i Kentaurens stjärnbild. Den kan inte ses från Sverige.
Däremot syns vår egen galax bra på natten just nu. Sedd från en mörk plats sträcker sig Vintergatsbandet över hela himlen.
Det nya porträttet på NGC 4945 är taget med kameran WFI (Wide Field Imager) vid 2,2-meter MPG/ESO-teleskopet vid La Silla-observatoriet i Chile.
Sedd från jorden ser galaxen avlång ut, men i själva verket är den en skiva som är flera gånger bredare än den är tjock, med ljusa band av stjärnor och glödande gas som virvlar runt galaxens mitt. Bilden är gjord med hjälp av särskilda filter som isolerar ljus från väte och andra heta gaser. Med den tekniken visar bilden både mörka stoftmoln där nya stjärnor bildas, och rödaktiga gasmoln som lyses upp av nyfödda heta stjärnor.
Supertungt svart hål
Andra observationer har avslöjat att NCG 4945 har en så kallad aktiv kärna, som avger mycket mer energi än till exempel Vintergatans kärna. Astronomer misstänker att det är ett supertungt svart hål som ligger bakom de extrema förhållanden i mitten av galaxen. På grund av sin massa drar svarta hål åt sig gas och stoft. När gasen hettas upp skiner den i ultraviolett ljus och röntgenstrålning.
De flesta stora spiralgalaxer, Vintergatan inräknad, härbärgerar tunga svarta hål, osynliga odjur som 'äter upp' gas och stoft och tillför energi till galaxen.
Kambiz Fathi, astronom vid Stockholms universitet, forskar om spiralgalaxer.
- Det här är en ganska spektakulär bild, säger han.
Han forskar om hur galaxers spiralarmar för in gas mot mitten.
- Det är just spiralarmarna som matar svarta hålet i mitten, förklarar han.
Enligt Kambiz Fathi vet astronomer ännu inte varför spiralgalaxer, som NGC 4945 och Vintergatan, är olika bra på att mata sina centrala svarta hål.
- Det kan bero på hur massan är fördelad i galaxen. Det blir så kallade resonanser som stoppar inflödet.
Mer information
Pressmeddelande på engelska, med bilder och video: http://www.eso.org/public/news/eso0931/
Kontakter
Henri Boffin
ESO
Garching, Germany
Tel: +49 89 3200 6222
E-post: hboffin@eso.org
Johan Warell (Presskontakt för Sverige)
ESO:s nätverk för vetenskaplig kommunikation
Skurup, Sverige
Tel: +46-706-494731
E-post: eson-sweden@eso.org
Om pressmeddelandet
| Pressmeddelande nr: | eso0931sv |
| Legacy ID: | PR 31/09 |
| Namn: | NGC 4945 |
| Typ: | Local Universe : Galaxy : Type : Spiral |
| Facility: | MPG/ESO 2.2-metre telescope |
| Instruments: | WFI |
Bilder
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