The life cycle of Stars Flashcards
What is a nebula?
Cloud of dust and gas in outer space
Formation of a star
- large ball of gas forms in the centre of the nebula, as it gets denser; more gas is pulled in
- this ball gets hotter forming a proto-star
- as this ball grows bigger, the centre gets so hot that the atoms squash together in a process called nuclear fusion.
- a new star is born
What is nuclear fusion?
The collision of two nuclei to make one larger nucleus, often with a large transfer of energy from mass to radiation.
How small stars die
gradually cool down ad expand to become a red giant. The outer layers of the star break away and form a planetary nebula. All that remains is a white-hot core of the star. This white dwarf eventually cools over time
How large stars die
Eventually cool and expand; but grow much bigger. They turn into red supergiants. The star then explodes in a gigantic explosion called a supernova. When a star goes supernova, it often outshines all the other stars I the galaxy put together.
What is a red giant?
Star that is large enough to fuse helium nuclei to make carbon
What is a white dwarf?
Remains of a small star which has run out of hydrogen to fuse into helium
What is a red supergiant?
Very large red giant star
What is a supernova?
Explosion of a massive star when its iron core suddenly collapses under its own weight
What happens during a supernova?
During a supernova, the core of the star is crushed down by immense gravitational forces. This can form a very dense kind of star just made up of neutrons. This neutron star spins very fast and sends pulses of radio waves to the Earth. If the star is even bigger, the core is crushed down into a tiny space - it forms a black hole.
What is a neutron star?
Small high density star left behind after a supernova. Often spins very rapidly.
What is a black hole?
Region of space that contains enough matter to prevent the escape of light from its gravity
Density of black holes
Black holes have near infinite densities due to their tiny volumes. All the mass of the core is crushed down into a space smaller than an atom. If you get too close to a black hole, you will be pulled in. The gravitational force is so large that nothing can escape.
