The stellar afterlife
Follow the life cycle of a Sun-like star
All stars begin life as protostars. But how their lives end depends mainly on their mass. For stars below or equal to eight times the mass of our Sun, stellar life can be pretty sedate in comparison with the lives of larger stars, which often explode in catastrophic explosions known as supernovae. Take a relatively tranquil tour of stellar life through to stellar death.
4 The main sequence
Just which evolutionary path a main sequence star decides to take depends on its mass. Stars eight times the mass of the Sun or more will explode in violent supernovae, leaving a neutron star or black hole in their wake. Stars that are smaller will take the easier and more sedate route.
5 Main-sequence fuel
The mass of a star dictates how long it’ll last at the main sequence. You may think the larger a star is, the longer it will last in its current state, but smaller stars take longer to burn up their fuel.
7 Shedding layers
The red giant is ready to push off its outer layers into a ring, forming a beautiful shell of diffuse gas known as a planetary nebula. The core, on the other hand, has collapsed in on itself.
3 A balancing act
The star is switched on and powered by hydrogen fusion. It’s industrious, happily burning hydrogen into helium as pressure forces its way outwards. Meanwhile, gravity pushes inwards towards the core. The two forces are balanced and the star is stable.
2 Make or break
Provided the protostar has at least around 0.08 times the Sun’s mass, the collapsing gas and dust burns hotter and hotter. Temperatures get so high that hydrogen is able to fuse into helium. If there’s not enough mass, the star fails and becomes a brown dwarf.
6 The red giant
When a main sequence star has used up all its hydrogen, it begins to swell into a red giant. The star’s core switches to helium fusion, pushing out an envelope that’s hundreds of times larger than the Sun’s radius and glowing with a reddish-orange hue.
1 A protostar is born
Stars begin their lives in clouds of gas and dust that have been drawn together by gravity. Their birthplace is known as a giant molecular cloud. When sections of these clouds collapse, a hot, young protostar bursts into existence.
8 Core subject
This core is known as a white dwarf, which is extremely dense. While collapsing, its electrons have been smashed together, forming what’s known as degenerate matter. This means that a more massive white dwarf has a smaller radius in comparison with its less massive counterpart. White dwarfs aren’t able to exceed more than 1.4 times the mass of the Sun.