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Terme du glossaire : Formation des étoiles

Description : La naissance d'une étoile résulte de l'effondrement gravitationnel de régions froides et denses, appelées noyaux, au sein de nuages moléculaires géants, que l'on trouve principalement dans les bras spiraux des galaxies. La formation des étoiles implique des processus physiques complexes, se produisant à différentes échelles et résultant des effets de la gravité, de la pression, du rayonnement, des champs magnétiques, de la turbulence, de la chimie, etc. En fonction de la masse du nuage parent et des processus d'accrétion au cours des phases de formation, la masse de l'étoile peut varier de 0,08 à quelques centaines de masses solaires. La plupart des étoiles ne se forment pas de manière isolée, mais au sein d'un amas d'étoiles. Au cours des phases de formation, un disque protostellaire se forme autour de l'étoile centrale, qui fournit à terme le matériau de construction nécessaire à la formation des planètes.

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Media associé


A dark cloud blocks out background stars. Infront, two jets of material shoot in opposite directions from a central object

Witnessing the birth of a star

Légende : A combination of radio and visible light imaged with the Atacama Large Millimeter/submillimeter Array (ALMA) and European Southern Observatory's New Technology Telescope (NTT) revealing birth of a star forming the Herbig-Haro object HH 46/47. ALMA observations shown in orange and green unveil the energetic jet from the central protostar otherwise hidden at visible wavelength due to dust obscuration and dense gas. NTT observations in pink and purple highlight the visible light from the jet emitted towards the observer.
Crédit : ESO/ALMA (ESO/NAOJ/NRAO)/H. Arce. Acknowledgements: Bo Reipurth Lien vers les crédits

License: CC-BY-3.0 Creative Commons (CC) Attribution 3.0 non transposé Icônes


Young stars form along a ribbon of gas

Stellar birth environment

Légende : Snapshot of the formation of multiple protostars in the Orion Molecular Clouds with a closer look at each of them with the Atacama Large Millimeter/submillimeter Array and Very Large Array. Such an image provides unique insights of the process and early stages of star formation as well as the influence of the parent cloud in which they form.
Crédit : ALMA (ESO/NAOJ/NRAO), J. Tobin; NRAO/AUI/NSF, S. Dagnello; Herschel/ESA Lien vers les crédits

License: CC-BY-3.0 Creative Commons (CC) Attribution 3.0 non transposé Icônes


The left image has finger-shaped clouds with bright edges. In the right image we see stars shining through those clouds

The Pillars of Creation in comparison

Légende : The 'Pillars of Creation' are a renowned astronomical feature situated within the Eagle Nebula in the Serpens constellation. The illustration provides a direct comparison between images captured by the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST), showcasing the pillars, which span several light years in diameter, in both visible light (also known as optical light) and infrared light. On the left are the pillars as seen by Hubble in visual light, taken in 2014. It displays dark pillars against an opaque background, with only a handful of visible stars. Conversely, the counterpart on the right is Webb’s near-infrared view published in 2022, penetrating the dust and revealing numerous stars of varying sizes. Their distance from Earth is approximately 6,500 to 7,000 light years. Within these pillars, new stars are constantly forming, making them a subject of extensive study by astronomers. Composed mostly of cool molecular hydrogen and small amounts of interstellar dust, they are subject to erosion by the intense ultraviolet radiation emitted by nearby massive and newborn stars, a process known as photoevaporation.
Crédit : NASA, ESA, CSA, STScI Lien vers les crédits

License: CC-BY-2.0 Creative Commons (CC) Attribution 2.0 Générique Icônes


A red patch mass of gas with a few dark bubbles with lighter edges and several lighter colored clusters and filaments

Herschel’s view of new stars and molecular clouds

Légende : This image shows the Westerhout 3, 4 and 5 star formation regions. This area has huge amounts of gas and dust. This gas and dust hides the physical processes going on in this region from studies using visible light. This image was taken in infrared light by the Herschel Space Observatory. This infrared light allowed Herschel to see deep into these star forming regions. In Westerhout 3, 4 and 5, huge, cold clouds of molecular hydrogen have collapsed into dense knots and filaments. Within these new structures the gas is dense and cold enough for it to collapse and form stars. These new stars give off powerful winds of charged particles, like stronger versions of the solar wind our sun gives off. These winds have combined to blow massive bubbles in the surrounding gas and dust. These are visible as the large darker voids in the image.
Crédit : ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech) Lien vers les crédits

License: CC-BY-3.0-IGO Creative Commons (CC) Attribution 3.0 Organisations Internationales Icônes