Life Cycle of a Star Describe: Define what a star is Secure: Describe how a star is made Exceeding: Identify the differences between the life cycles of different size stars Entrance Activity Try to write down the names of the 2 different theories of the origins of the universe Tool Box – Key Words Stars Nebula Protostar Red giant Fusion White dwarf Supernova Black hole Neutron star

Learning activity What is a Star? In groups discuss what you think a star is and what features make it a star and not another celestial body https://www.youtube.com/watch?v=TqLghoGLez4

Star A star is a ball of plasma undergoing nuclear fusion. Key word Star A star is a ball of plasma undergoing nuclear fusion. Stars give off large amounts of energy in the form of electromagnetic radiation.

Life Cycle of a Star Describe: Define what a star is Secure: Describe how a star is made Exceeding: Identify the differences between the life cycles of different size stars Entrance Activity Try to write down the names of the 2 different theories of the origins of the universe Tool Box – Key Words Stars Nebula Protostar Red giant Fusion White dwarf Supernova Black hole Neutron star

Nebula – Birth of Star Stars are formed in a Nebula. Teacher explanation Nebula – Birth of Star Stars are formed in a Nebula. A Nebula is a very large cloud of gas and dust in space.

Protostars Gravity makes dense region of gas more compact Teacher explanation Protostars Gravity makes dense region of gas more compact Soon take on a definite shape and are called protostars.

Formation of a Star

Birth of a star Watch the video about the birth of stars and make notes on what you see. https://www.youtube.com/watch?v=80eMTnnLjhs

Life Cycle of a star Describe: Define what a star is Secure: Describe how a star is made Exceeding: Identify the differences between the life cycles of different size stars Entrance Activity Try to write down the names of the 2 different theories of the origins of the universe Tool Box – Key Words Stars Nebula Protostar Red giant Fusion White dwarf Supernova Black hole Neutron star

Life cycle of main sequence stars They stay stable for around 10 billion years When they have fused most of their hydrogen into Helium. The core is not hot enough to withstand gravity and it collapses Outer layers expand and form a red giant Fusion inside the red giant combines helium nuclei to make heavier elements. It remains as a red giant for around a billion years throwing off a shell of gas Then it gets pulled together by gravity causing it to collapse into a white dwarf No fusion happens in a white dwarf, it cools over a billion years to form a black dwarf

Life cycle of massive stars Stars with larger masses are hotter and brighter They fuse hydrogen into helium very fast becoming red supergiant It then collapses and explodes into a supernova The outer layers of the supergiant are cast off and expand outwards. If what is left is 4 or more times the mass of that star then gravity pulls it together to form a black hole. If its smaller then gravity pulls it together to form a dense neutron star

Have a go at this worksheet. You have 8 minutes. When you have finished you should swap with the person next to you

Life Cycle of a Star Describe: Define what a star is Secure: Describe how a star is made Exceeding: Identify the differences between the life cycles of different size stars Entrance Activity Try to write down the names of the 2 different theories of the origins of the universe Tool Box – Key Words Stars Nebula Protostar Red giant Fusion White dwarf Supernova Black hole Neutron star