The Life Cycle Of A Star Flashcards
How do stars initially form?
When the force of gravity causes gas and dust to spiral together to a single point to form a protostar
What is the second step in the formation of a star?
Gravitational energy is converted into heat energy to the temperatures rise, the hydrogen nuclei then undergo nuclear fusion to form helium nuclei and give out massive amount of heat and light (a star is born)
What makes a star Stable for a long period?
The heat created by nuclear fusion provides an outward pressure to balance the force of gravity
How does the star maintain its energy output for millions of years?
Due to the massive amounts of hydrogen it consumes
What is it called during the stable period?
Main sequence star (lasts billions of years)
What happens when the hydrogen begins to run out?
Heavier elements such as iron are made by nuclear fusion of helium. The star then swells into a red giant if it’s a small star or super red giant if it’s a big star
What is a red giant red?
Because the surface cools
What is the stage after red giant?
Small to medium sized starts become unstable and ejects it’s outer layer of dust and gas as a planetary nebula
This leaves behind a hot dense solid core (white dwarf) which just cools down to a black dwarf and eventually disappears
What happens after a big star is a super red giant?
How again more brightly as they undergo more fusion and expand and contract several times forming elements as heavy as iron in various nuclear reactions
They eventually explode In a supernova forming elements heavier than iron and ejecting them into the universe to form new planets and stars
What does the exploding supernova do?
Throws the outer layer of dust and gas into space leaving a very dense core called a neutron star
If the stars big enough it becomes a black hole
What is the life cycle of a small star?
Protostar
Main sequence star
Red giant
White dwarf
What is the life cycle of a large star?
Protostar Main sequence star Red super giant Supernova Neutron star Black hole
