2. Aim: What is the life cycle of a star? I. Star – a massive, gaseous body held together by gravity and generally emitting light B. Life cycle of low massive stars (our sun) 1. Starts as interstellar cloud 2. Protostar – a star still in its formation stage 3. Star A. The fate of a star depends on its mass. The more mass, the shorter its life and more dramatic its death.

3. 4. Red Giant – when 90% of hydrogen is used up, the star expands and grows larger (100x). Outer shell becomes cooler (that is why it is red in color). Helium eventually burns out and grows even larger. 5. White Dwarf – after there is no energy left, it cools and turns into white dwarf. a. same diameter as earth b. same mass as sun

4. C. Life cycle of high massive stars 1. Same beginning as low mass stars a. Interstellar cloud, protostar, massive star, red giant 2. Supernova explosion 3. Becomes either a neutron star or a black hole