The life cycle of stars
Stars form from a cloud of gas and dust called a nebula
The gas and dust collapse under their own pressure to form a protostar. As more and more matter is packed into the protostar, it gets much denser and hotter until conditions are right for nuclear fusion to take place
Atoms of hydrogen are joined together to form helium. The outward gas pressure is balanced by the inward pull of gravity. This new star is called a Main sequence star, like our sun.
Once all the hydrogen fuel has become helium its primary fuel has run out. The outward force of the gas pressure is no longer balance by the inward force of gravity and it dies. The fate of the star depends on its size
Red giant
Once the hydrogen is used up, the star contracts and this generates enough energy to restart nuclear fusion. Helium is used as a fuel, being converted to carbon. The star expands as the fuel runs out, burning hydrogen in its core to become 100 times bigger - this is called a red giant
Outer layers of the star and the carbon are blown away to form planetary nebulas from which new stars and planets may form. The centre of the star no longer has the gas pressure so collapses under its own gravity to form a small, dense core called a white dwarf
As this star loses energy it will become a black dwarf
The gas and dust collapse under their own pressure to form a protostar. As more and more matter is packed into the protostar, it gets much denser and hotter until conditions are right for nuclear fusion to take place
Atoms of hydrogen are joined together to form helium. The outward gas pressure is balanced by the inward pull of gravity. This new star is called a Main sequence star, like our sun.
Once all the hydrogen fuel has become helium its primary fuel has run out. The outward force of the gas pressure is no longer balance by the inward force of gravity and it dies. The fate of the star depends on its size
Red giant
Once the hydrogen is used up, the star contracts and this generates enough energy to restart nuclear fusion. Helium is used as a fuel, being converted to carbon. The star expands as the fuel runs out, burning hydrogen in its core to become 100 times bigger - this is called a red giant
Outer layers of the star and the carbon are blown away to form planetary nebulas from which new stars and planets may form. The centre of the star no longer has the gas pressure so collapses under its own gravity to form a small, dense core called a white dwarf
As this star loses energy it will become a black dwarf
Red Super giant
These stars are brighter than the sun and appear blue so are called blue super giants. When the hydrogen runs out, the star expands to become a red super giant. Red super giants are bigger but cooler stars.
The star is unstable and the inner core collapses in less than a second causing an explosion called a supernova.
Very large stars: the remains of the supernova form a star that pulses. They are very dense and may take the form of a pulsar - this is a rotating neutron star that emits radio waves
Very very large stars: there is such a massive force of gravity, that the matter collapses to form a black hole. Gravity is so strong that not even gravity can escape
These stars are brighter than the sun and appear blue so are called blue super giants. When the hydrogen runs out, the star expands to become a red super giant. Red super giants are bigger but cooler stars.
The star is unstable and the inner core collapses in less than a second causing an explosion called a supernova.
Very large stars: the remains of the supernova form a star that pulses. They are very dense and may take the form of a pulsar - this is a rotating neutron star that emits radio waves
Very very large stars: there is such a massive force of gravity, that the matter collapses to form a black hole. Gravity is so strong that not even gravity can escape