P16 Flashcards
How are stars born?
It starts with massive clouds of dust and gas in space.
These clouds of Dust and gas are pulled together by their gravitational attraction.
The clouds join, becoming more and more concentrated, forming a protostar.
As the protostar becomes denser it gests hotter and this energy causes lighter nuclei to join together, energy is released from this fusion reaction so the protostar gets even hotter.
Getting hotter and brighter it starts to shine giving birth to a star.
The outward force from pressure of expanding hot gas is balanced by the force of the star’s gravity.
As the stars gravity pulls smaller amounts of dust and gas together forming planets in orbit of the star.
Main sequence star
The star enters a long stable period where the outward pressure caused by the nuclear fusion that tries to expand the star balances from the force of gravity pulling everything inwards. In this stable period it’s called a main sequence star and last for billions of years.
How are red giants and red super giants formed?
Eventually the hydrogen begins to run out. The star then swells into a red giant (if it is a small star) or a red super giant (if it is a larger star). It becomes red because the surface cools. Fusion of helium (and other elements) occurs. Heavier elements (up to iron) are created in the core of the star.
