De levensloop van sterren

Sterren lijken onveranderlijk aan de hemel te staan. Nadere bestudering laat wel verschillende kenmerken zien zoals kleur, temperatuur en grootte. Astronomen hebben in de afgelopen jaar ontdekt hoe dit inzicht geeft in de levensloop van sterren. Marc de Louw neemt het publiek mee op een tijdreis van vele miljoenen jaren van gaswolk tot witte dwerg of zwart gat.

Born from clouds of gas and dust, stars like our Sun spend most of their lifetime slowly burning their primary nuclear fuel, hydrogen, into the heavier element helium. After leading this bright and shiny life for several billion years, their fuel is almost exhausted and they start swelling, pushing the outer layers away from what has turned into a small and very hot core. These “middle-aged” stars become enormous, hence cool and red — red giants. All red giants exhibit a slow oscillation in brightness due their rhythmic “breathing” in and out, and one third of them are also affected by additional, slower and mysterious changes in their luminosity. After this rapid and tumultuous phase of their later life, these stars do not end in dramatic explosions, but die peacefully as planetary nebulae, blowing out everything but a tiny remnant, known as white dwarf.