Stars

1. Stars “Balls of burning gas billions of miles away”

2. Star information • The core of a star is like a giant thermonuclear reactor • They are mostly made up of hydrogen (and dust) • Scientists can observe stars and make hypothesis about them based on understanding light, wavelengths and electromagnetic radiation

3. The birth of a star • Clumps of gas and dust floating around in a nebula get draw together by their own gravity • This clump of material attracts more and more bits until the pressure causes the centre to collapse in on itself (now it is a protostar) • With enough dust and pressure, the centre will eventually reach 10 000 000 °C, and all the atoms there will fuse into larger atoms (hydrogen becoming helium) • This is called fusion

4. Star life cycle (Figure 11.3 pg 371) • All stars start in a nebula, but from there one of three things can happen • 1: low mass stars • These spend most of their lives as cool red dwarfs, then hotter small dim white dwarfs, then they burn out • 2: intermediate mass stars • These burn faster than low mass stars, they become a red giant, then a white dwarf and finally a black dwarf (our sun is one of these) • 3: High mass stars • Consume fuel very quickly, become a supergiant, which later explodes in a supernova. This can either collapse into a black holeor a small neutron star

5. Black holes • The centre has such intense gravity that nothing can escape it, even light!!! • Because we can’t see them we can only find them by measuring how they affect objects around them