@prefix mdl: . @prefix skos: . @prefix dc: . @prefix xsd: . mdl:-LR26WLQ3-5 skos:prefLabel "Hertzsprung-Russel diagram"@en, "diagramme HR"@fr ; a skos:Concept ; skos:broader mdl:-NGLWSPST-G . mdl:-NGLWSPST-G dc:modified "2022-09-30"^^xsd:date ; skos:narrower mdl:-X63CG8SM-P, mdl:-JJ3S8Z3T-L, mdl:-LR26WLQ3-5, mdl:-Z0H4DHZC-P ; skos:related mdl:-WRFHB6ZP-Z, mdl:-KGLNJX2H-P, mdl:-K7RMK0T3-B, mdl:-MBS2NS6G-7, mdl:-BDJNG533-7 ; skos:hiddenLabel "stellar evolutions"@en, "évolutions stellaires"@fr, "Stellar evolution"@en, "Evolution stellaires"@fr, "Evolution stellaire"@fr, "star evolutions"@en ; skos:definition "L'évolution d'une étoile, ou évolution stellaire, désigne l'ensemble des phénomènes allant de la formation à la \"mort\" d'une étoile. Elle peut être décomposée en plusieurs phases principales dont la formation de l'étoile, son séjour sur la séquence principale et sa phase finale. Durant sa vie, une étoile émet des particules et des rayonnements électromagnétiques (dont une partie sous forme de rayonnements visibles) grâce à l'énergie dégagée par les réactions de fusion nucléaire produites dans les zones internes de l'étoile. L'analyse spectrale de ces émissions révèle certaines caractéristiques de l'étoile, et par conséquent permet de déterminer le stade d'évolution où elle est parvenue. La plus grande partie de l'existence de l'étoile se passe sur la séquence principale, où elle fusionne de l'hydrogène pour former de l'hélium. Une fois le cœur de l'étoile épuisé en hydrogène, elle quitte la séquence principale pour évoluer vers d'autres stades d'évolution ; le stade ultime étant un objet compact : une naine blanche (et à terme une naine noire), une étoile à neutrons ou encore un trou noir. (Wikipedia, L'Encylopédie Libre, https://fr.wikipedia.org/wiki/%C3%89volution_stellaire)"@fr, "Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star. Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red-giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their existence, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs. (Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Stellar_evolution)"@en ; skos:prefLabel "stellar evolution"@en, "évolution stellaire"@fr ; skos:exactMatch , , ; a skos:Concept ; skos:broader mdl:-RJN69ZZ0-P ; skos:altLabel "star evolution"@en ; skos:inScheme mdl: . mdl:-BDJNG533-7 skos:prefLabel "étoile de la branche horizontale"@fr, "horizontal branch star"@en ; a skos:Concept ; skos:related mdl:-NGLWSPST-G . mdl:-MBS2NS6G-7 skos:prefLabel "main-sequence star"@en, "étoile de la séquence principale"@fr ; a skos:Concept ; skos:related mdl:-NGLWSPST-G . mdl:-Z0H4DHZC-P skos:prefLabel "disque d'accrétion"@fr, "accretion disk"@en ; a skos:Concept ; skos:broader mdl:-NGLWSPST-G . mdl:-KGLNJX2H-P skos:prefLabel "asymptotic giant branch"@en, "branche asymptotique des géantes"@fr ; a skos:Concept ; skos:related mdl:-NGLWSPST-G . mdl:-X63CG8SM-P skos:prefLabel "star accretion"@en, "accrétion stellaire"@fr ; a skos:Concept ; skos:broader mdl:-NGLWSPST-G . mdl:-JJ3S8Z3T-L skos:prefLabel "explosion stellaire"@fr, "stellar explosion"@en ; a skos:Concept ; skos:broader mdl:-NGLWSPST-G . mdl:-RJN69ZZ0-P skos:prefLabel "stellar physics"@en, "physique des étoiles"@fr ; a skos:Concept ; skos:narrower mdl:-NGLWSPST-G . mdl: a skos:ConceptScheme . mdl:-K7RMK0T3-B skos:prefLabel "naine noire"@fr, "black dwarf"@en ; a skos:Concept ; skos:related mdl:-NGLWSPST-G . mdl:-WRFHB6ZP-Z skos:prefLabel "red-giant branch"@en, "branche des géantes rouges"@fr ; a skos:Concept ; skos:related mdl:-NGLWSPST-G .