Stellar Evolution Flashcards
What colour star has the coolest surface temperature?
A red star
What colour star has the hottest surface temperature?
A blue star
What are the stages that lead to a star forming?
Nebula -> protostar -> Main Sequence star
How is a protostar formed from a nebula?
-The force of gravity within a nebula pulls particles closer together until a hot ball of gas forms, which is called a protostar.
How is a main sequence star formed from a protostar?
-As particles are pulled closer together, density increases
-This higher frequency in collisions lead to temperature-increasing
-This higher temperature leads to nuclear fusion reactions in the protostar core
-Once the protostar initiates fusion, it is now labeled a Main Sequence star.
Describe the sequence a low mass star would undergo as it finishes its life cycle
Main sequence star- Red giant - planetary nebula - white dwarf
Why would a Main sequence star turn into a red giant?
As hydrogen eventually fuses into helium and with temperatures not being high enough to fuse helium to other elements, outward pressure due to fusion decreases. Leading gravity to take over and the star begins to collapse.
What happens after a main sequence star collapses?
-The helium nuclei are pushed together due to the collapse leading to more collisions
-This increase in energy leads to fusion to start again
- leading in an outpour of energy
What happens after fusion leads to an outpour of energy in a main sequence star?
-The outer layers of the star will expand, cool down and therefore appear more red
How would a Red giant turn into a planetary nebula?
-When the core of the red giant no longer has the energy to fuse helium nuclei, outward pressure from fusion would stop
-The gravitational force would take over and compress the inner layers of the star
-Outer layers would drift outward and form a planetary nebula
How does a planetary nebula turn into a white dwarf?
-As the outer layers of the planetary nebula continue to drift out into space, all is left is a small, dense and bright core. This is called a white dwarf
