1. How are stars born? Galaxies are clouds of dust and gas called nebulae
hydrogen gas in the nebula becomes clumped together by gravity
cloud begins to spin
over millions of years, more hydrogen atoms are pulled into the spinning cloud
Collisions between hydrogen atoms become more frequent  hydrogen gases heat up.
Temperatures above 15,000,000oC  pressure increases and nuclear fusion (the combining of 2 atoms into 1)
2 hydrogen atoms  helium atom
Great heat and light is given off  a new star (protostar)

2. What is the life cycle of a star?
Protostar  nuclear fusion
Eventually, the star will run out of hydrogen
The helium core shrinks and heats up
The outer shell is still composed mainly of hydrogen
Heating of the helium  outer shell to expand greatly.
As it expands  cools and turns into a red giant.

3. Depending on the mass of the star, 1 of 2 things can happen to the red giant.
Low mass stars turn into white dwarf
It shines bright white light before it turns into a dead star (this will be the fate of our sun).
High mass stars turn into a nova , then break apart in an explosion called a supernova
remnants of a supernova serve as a birth place for stars.
a black hole can form

4. What is a black hole?
After a supernova explosion, the core remains so massive, that it collapses into an object smaller than a neutron star.
The gravity of the core is so strong that light can’t escape the surface
Swallows gases and matter as if it were a vacuum cleaner.

5. Assignment
Life Cycle of Stars Foldables