Pressemeddelelse

Opklaring af mysteriet om tunge stjerners fødsel

alle stjerner fødes på samme måde

14. juli 2010

Astronomer har lavet det første billede af en støvet skive, der ligger tæt omkring en tung babystjerne. Det er et direkte tegn på, at tunge stjerner dannes på samme måde som deres mindre brødre. Denne opdagelse, der er gjort takket være en kombination af ESO’s teleskoper, er beskrevet i en artikel i denne uges udgave af Nature.

”Vores observationer viser en skive omkring en helt ung, tung stjerne, som nu er fuldt udviklet,” siger Stefan Kraus, der stod i spidsen for undersøgelsen. ”Man kan sige, at ungen er ved at udklække!”

Holdet af astronomer har set på et objekt, der er kendt under det kryptiske navn IRAS 13481-6124. Objektet indeholder en ung stjerne, der er tyve gange tungere end Solen og har en radius, som er fem gange større. Stjernen, der stadig er omgivet af sin puppe, ligger i stjernebilledet Centaurus (Kentauren) omkring 10.000 lysår væk.

Fra arkivbilleder lavet med NASA’s Spitzer-rumteleskop samt fra observationer foretaget med APEX 12 meter submillimeter-teleskopet har astronomer opdaget tilstedeværelsen af en jetstrøm.

”Sådanne jetstrømme er almindelige omkring unge, lette stjerner og indikerer normalt tilstedeværelsen af en skive,” siger Kraus.

Skiver omkring stjerner er en væsentlig ingrediens i dannelsesprocessen for lette stjerner, som vores egen stjerne, Solen. Men det vides ikke, om sådanne skiver også er til stede under dannelsen af stjerner, der er mere end ca. ti gange tungere end Solen, hvor det stærke lys, der udsendes, måske kan forhindre materiale i at falde ned på stjernen. For eksempel er det blevet foreslået, at tunge stjerner dannes, når mindre stjerner smelter sammen.

For at opdage og forstå egenskaberne af skiven omkring IRAS 13481-6124, har astronomerne anvendt ESO’s Very Large Telescope Interferometer (VLTI). Ved at kombinere lyset fra tre af VLTI’s 1,8 meter hjælpeteleskoper med AMBER-instrumentet har astronomerne mulighed for at se detaljer, der svarer til dem, et teleskop med et spejl på 85 meter i diameter ville kunne se. Den resulterende opløsningsevne er ca. 2,4 millibuesekunder, hvilket svarer til at kunne skelne et skruehoved på den Internationale Rumstation fra jordoverfladen. Det er mere end ti gange den opløsningsevne, der er mulig med de nuværende rumteleskoper til synligt lys.

Med denne enestående kapacitet, suppleret med observationer med et andet af ESO’s teleskoper, 3,58 meter New Technology Telescope på La Silla, var Kraus og hans kolleger i stand til at opdage en skive omkring IRAS 13481-6124.

”Det er første gang, vi har kunnet lave billeder af de indre dele af skiven omkring en tung, ung stjerne,” siger Kraus. ”Vores observationer viser, at dannelsen virker ens for alle stjerner, uanset hvor tunge de er.”

Astronomerne konkluderer, at systemet er omkring 60.000 år gammelt og at stjernen har nået sin endelige masse. På grund af stjernens intense lys – den er 30.000 gange mere lysstærk end Solen – vil skiven snart begynde at fordampe. Skiven er bredere i kanten end tæt på stjernen. Den strækker sig over 130 gange afstanden mellem Jorden og Solen – eller 130 astronomiske enheder (AU) – og er lige så tung som stjernen, hvilket er omtrent tyve gange tungere end Solen. Desuden har det vist sig, at de indre dele af skiven er blottet for støv.

”Yderligere observationer med Atacama Large Millimeter/submillimeter Array (ALMA), der for tiden er ved at blive bygget i Chile, kan give mange oplysninger om disse indre dele, og give os mulighed for bedre at forstå, hvordan tunge babystjerner er blevet så tunge,” slutter Kraus.

Mere information

Denne forskning er præsenteret i en artikel i denne uges udgave af tidsskriftet Nature (“A hot compact dust disk around a massive young stellar object”, af S. Kraus et al.).

Holdet er sammensat af Stefan Kraus (University of Michigan, USA), Karl-Heinz Hofmann, Karl M. Menten, Dieter Schertl, Gerd Weigelt, Friedrich Wyrowski og Anthony Meilland (Max-Planck-Institut für Radioastronomie, Bonn, Tyskland), Karine Perraut (Laboratoire d'Astrophysique de Grenoble, Frankrig), Romain Petrov og Sylvie Robbe-Dubois (Université de Nice Sophia-Antipolis/CNRS/Observatoire de la Côte d’Azur, Frankring), Peter Schilke (Universität zu Köln, Tyskland) og Leonardo Testi (ESO).

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 14 medlemslande: Belgien, Danmark, Finland, Frankrig, Holland, Italien, Portugal, Schweiz og Storbritannien, Spanien, Sverige, Tjekkiet, Tyskland og Østrig. Flere lande har udtrykt interesse i medlemskab. ESO’s aktiviteter er fokuseret på design, konstruktion og drift af jordbaserede observationsfaciliteter for astronomi for at muliggøre vigtige videnskabelige opdagelser. 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, og VISTA, som er verdens største kortlægningsteleskop. ESO er den europæiske partner i et revolutionerede astronomisk teleskop kaldet ALMA, det største igangværende astronomiske projekt. ESO planlægger i øjeblikket et 42 meter optisk/nær-infrarødt teleskop kaldet European Extremely Large Telescope (E-ELT), der vil blive ”verdens største øje mod himlen”.

Links

Kontakter

Stefan Kraus
University of Michigan
USA
Tel: +1 734 615 7374
E-mail: stefankr@umich.edu

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

Henri Boffin
ESO, La Silla Paranal and E-ELT Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6222
Mobil: +49 174 515 43 24
E-mail: hboffin@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 eso1029 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.:eso1029da
Navn:Protoplanetary disc
Type:Milky Way : Star : Circumstellar Material : Disk : Protoplanetary
Facility:New Technology Telescope, Very Large Telescope, Very Large Telescope Interferometer
Instruments:AMBER, LABOCA, SABOCA
Science data:2010Natur.466..339K

Billeder

A disc around a massive baby star (artist's impression)
A disc around a massive baby star (artist's impression)
tekst kun tilgængelig på engelsk
The disc around IRAS 13481-6124
The disc around IRAS 13481-6124
tekst kun tilgængelig på engelsk
IRAS 13481-6124 and its cradle
IRAS 13481-6124 and its cradle
tekst kun tilgængelig på engelsk
Around IRAS 13481-6124
Around IRAS 13481-6124
tekst kun tilgængelig på engelsk

Videoer

Zoom-in on IRAS 13481-6124
Zoom-in on IRAS 13481-6124
tekst kun tilgængelig på engelsk

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