Absolut gehør for planetdannelse med DSHARP
Ugens billede viser 20 flotte protoplanetariske skiver fanget i forbindese med ALMAs første store observationsprogram Disk Substructures at High Angular Resolution Project (DSHARP).Her focuseres på at indsamle data, som dækker timelange observationer over flere måneder, og de 20 nære protoplanetariske skiver her er registreret i første omgang. Målet er at lære mere om de tidligste trin i planetdannelsen, og de enorme datamængder fra projektet er netop blevet offentliggjorte.
Forskerne har længe ment, at planetsystemer sandsynligvis stammer fra de såkaldte protoplanetariske skiver - aflange cirkler, spiraler eller ellipser af gas og støv, som dannes omkring protostars i de tidlige stadier af deres udvikling. Den proces hvormed planeter bliver til ud fra disse diffuse skiver er dog ikke helt forstået. Det er særligt udfordrende at forstå de allertidligste trin i udviklingen; der hvor støv i en skive samles til planetesimaler, som så igen er de 'frø', som planeter dannes fra.
Astronomerne ved, at en planets første vækstperiode fra individuelle korn til en klump, som er måske nogle kilometer i diameter, må ske hurtigt efter astronomiske forhold, men der har manglet observationer, så derfor har det været svært at finde ud af, hvad fysikken bag denne proces er. Heldigvis er det nu ændret, fordi vi nu har teleskoper som ALMA til rådighed.
I sidste ende håber astronomerne præcist at kunne forudsige hvilken type planetsystem, som vil udvikle sig fra en givet type skive. Programmet DSHARP bringer os et skridt videre imod det mål, fordi vi nu har et detaljeret overblik over de underliggende strukturer - altså de forskelllige mønstre af mørke og lyse kredse og spiraler, som kan ses i de enkelte skiver.
Historien fortsætter næste uge med næste billede af tre, som omhandler de nyeste opdagelser med DSHARP.
Kilde:ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello
Om billedet
| Id: | potw1904a |
| Sprog: | da |
| Type: | Kollage |
| Udgivelsesdato: | 28. januar 2019 06:00 |
| Størrelse: | 6896 x 8620 px |
Om objektet
| Type: | Milky Way : Star : Circumstellar Material : Disk : Protoplanetary |
Billedformater
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