Pressemeddelelse

Betelgeuses flammer

Nyt billede afslører vidtstrakt stjernetåge omkring berømt superkæmpestjerne

23. juni 2011

Ved hjælp af VISIR-instrumentet på ESO’s Very Large Telescope (VLT) har astronomer optaget det hidtil mest detaljerede billede af en indviklet og klar stjernetåge omkring superkæmpestjernen Betelgeuse. Denne struktur, som ligner flammer, der strømmer ud fra stjernen, bliver dannet i takt med, at dette stjernemonstrum kaster sit materiale ud i rummet.

Betelgeuse er en rød superkæmpe i stjernebilledet Orion og en af de klareste stjerner på nattehimlen. Den er også en af de største, da den har næsten samme størrelse som Jupiters bane – omtrent fire og en halv gange diameteren af Jordens bane. Billedet fra VLT viser den omkringliggende stjernetåge, der er meget større end superkæmpen selv. Den strækker sig 60 milliarder kilometer væk fra stjernens overflade – cirka 400 gange afstanden mellem Jorden og Solen.

Røde superkæmper som Betelgeuse repræsenterer en af de sidste livsfaser for en tung stjerne. I denne kortvarige fase øger stjernen sin størrelse og slynger materiale ud i rummet  med en enorm hast – på bare 10.000 år kaster umådelige mængder af materiale ud (svarende til Solens masse).

Der er to forskellige fænomener på banen, når en stjerne som Betelgeuse udslynger materiale. Den første er dannelsen af kæmpemæssige vifteagtige gasskyer (selv om de er meget mindre end den stjernetåge, der nu er optaget), der strækker sig ud i rummet fra stjernens overflade, og som tidligere er blevet set med NACO-instrumentet på VLT [1]. Det andet fænomen, der forårsager udslyngningen af de vifteformede gasskyer, er den voldsomme op- og nedadgående bevægelse af gigantiske bobler i Betelgeuses atmosfære – ligesom kogende vand, der cirkulerer i en kedel (læs mere i eso0927).

De nye resultater viser, at de vifteformede skyer tæt på stjernen sandsynligvis er forbundne til de strukturer i den ydre del af stjernetågen, der nu er optaget i infrarødt lys af VISIR. Stjernetågen er ikke tydelig i synligt lys, fordi den meget lysstærke Betelgeuse fuldstændig overstråler den. Den uregelmæssige, asymmetriske form, som tågen har, antyder, at stjernen ikke har udslynget sit materiale på en symmetrisk måde. Boblerne af stjernemateriale og de gigantiske vifteformede gasskyer som de frembringer, er måske ansvarlige for stjernetågens klumpede udseende.

Materialet, der ses på det nye billede, er højst sandsynligt lavet af silikat og aluminiumsoxyd-støv. Det er samme materiale, der udgør det meste af skorpen på Jorden og andre stenplaneter. På et tidspunkt i en fjern fortid blev Jordens silikater dannet af en tung (og nu afdød) stjerne magen til Betelgeuse.

I dette sammensatte billede er NACO’s tidligere observationer af de vifteformede gasskyer gengivet i den midterste skive. Den lille røde cirkel i midten har en diameter svarende til ca. fire en halv gange diameteren af Jordens bane og repræsenterer Betelgeuses synlige overflade. Den sorte skive svarer til en meget lysstærk del af billedet, der er blevet maskeret for at få den mere lyssvage stjernetåge til at træde frem. Billedet fra VISIR er taget gennem infrarøde filtre, der er følsomme over for stråling af forskellig bølgelængde. Blå svarer til kortere bølgelængder og rød til længere. Billedets synsfelt er 5,63 x 5,63 buesekunder.

Noter

[1] NACO er et instrument på VLT, der kombinerer Nasmyth Adaptive Optics System (NAOS) med Near-infrared Imager and Spectrograph (CONICA). Det giver mulighed for at optage billeder med adaptiv optik, billeddannende polarimetri, koronagrafi og spektroskopi ved nærinfrarøde bølgelængder.

Mere information

Denne forskning er præsenteret i en videnskabelig artikel, der udkommer i tidsskriftet Astronomy & Astrophysics.

Forskerholdet består af P. Kervella (Observatoire de Paris, Frankrig), G. Perrin (Observatoire de Paris), A. Chiavassa (Université Libre de Bruxelles, Belgien), S. T. Ridgway (National Optical Astronomy Observatories, Tucson, USA), J. Cami (University of Western Ontario, Canada; SETI Institute, Mountain View, USA), X. Haubois (Universidade de Sao Paulo, Brasilien) and T. Verhoelst (Instituut voor Sterrenkunde, Leuven, Holland).

ESO, det Europæiske Syd Observatorium, er den mest fremtrædende internationale astronomi-organisation i Europa og verdens mest produktive astronomiske observatorium. ESO har i dag følgende 15 medlemslande: Belgien, Brasilien, Danmark, Finland, Frankrig, Holland, Italien, Portugal, Schweiz og Storbritannien, Spanien, Sverige, Tjekkiet, Tyskland og Østrig. ESO’s aktiviteter er fokuseret på design, konstruktion og drift af jordbaserede observationsfaciliteter for at muliggøre vigtige videnskabelige opdagelser inden for astronomi. ESO spiller også en ledende rolle for at fremme og organisere samarbejdet inden for astronomisk forskning. I Chile driver ESO tre unikke observatorier i verdensklasse: La Silla, Paranal og Chajnantor. På Paranal driver ESO Very Large Telescope (VLT), der er verdens mest avancerede astronomiske observatorium til observationer i synligt lys samt to kortlægningsteleskoper. VISTA arbejder i infrarødt lys og er verdens største kortlægningsteleskop, mens VLT Survey Telescope (VST) er det største teleskop, der udelukkende er bygget til at kortlægge himlen i synligt lys. ESO er den europæiske partner i et revolutionerede astronomisk teleskop kaldet ALMA, det største igangværende astronomiske projekt. ESO planlægger i øjeblikket et 40 meter optisk/nær-infrarødt teleskop kaldet European Extremely Large Telescope (E-ELT), der vil blive ”verdens største øje mod himlen”.

Links

Kontakter

Pierre Kervella
LESIA, Observatoire de Paris / CNRS, Université Pierre et Marie Curie / Université Denis Diderot (Paris 7)
Paris, France
Tel: +33 1 45 07 79 66
E-mail: Pierre.Kervella@obspm.fr

Guy Perrin
LESIA, Observatoire de Paris / CNRS, Université Pierre et Marie Curie / Université Denis Diderot (Paris 7)
Paris, France
Tel: +33 1 45 07 79 63
E-mail: guy.perrin@obspm.fr

Richard Hook
ESO, La Silla, Paranal, E-ELT and Survey Telescopes Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
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

Connect with ESO on social media

Dette er en oversættelse af ESO pressemeddelelse eso1121 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.:eso1121da
Navn:Betelgeuse
Type:Milky Way : Star : Evolutionary Stage : Red Supergiant
Facility:Very Large Telescope
Instruments:NACO, VISIR
Science data:2011A&A...531A.117K

Billeder

The flames of Betelgeuse
The flames of Betelgeuse
tekst kun tilgængelig på engelsk
Betelgeuse i stjernebilledet Orion
Betelgeuse i stjernebilledet Orion

Videoer

Zooming in on the flames of Betelgeuse
Zooming in on the flames of Betelgeuse
tekst kun tilgængelig på engelsk

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