1. Nebula to Protostar Giant molecular clouds within a nebula contract under the gravitational pressure, increasing its thermal energy. CO, NO, OH- Giant molecular clouds within a nebula contract under the gravitational pressure, increasing its thermal energy. CO, NO, OH- The gasses inside condense to form a small dense core, surrounded by a gas cocoon in the form of a tear drop. The gasses inside condense to form a small dense core, surrounded by a gas cocoon in the form of a tear drop.

2. Protostar to Main Sequence Star Protostar = hot enough to radiate infrared radiation but not hot enough to generate energy by nuclear fusion Protostar = hot enough to radiate infrared radiation but not hot enough to generate energy by nuclear fusion As it sheds its “cocoon” there is an empty space around the star and gas. As it sheds its “cocoon” there is an empty space around the star and gas. Its gravity attracts more mass and as it gains more mass it also gets more heat Its gravity attracts more mass and as it gains more mass it also gets more heat Nuclear fusion occurs Nuclear fusion occurs It’s now a star! It’s now a star!

3. Main Sequence Stars Hydrostatic equilibrium Hydrostatic equilibrium Energy Conservation Energy Conservation Energy Transport Energy Transport Proton Proton Fusion Proton Proton Fusion 90% of stars 90% of stars Mass increases as luminosity increases L=M^3.5 Mass increases as luminosity increases L=M^3.5

4. Main Sequence Stars Main sequence stars mainly stay in their position Main sequence stars mainly stay in their position They do grow, but in mass, not in T They do grow, but in mass, not in T  radius increase  radius increase  move toward giant phase  move toward giant phase High Mass Stars – start and die in one place High Mass Stars – start and die in one place

5. Red Giant to Variable Stage Bright and luminous  large in size Bright and luminous  large in size Begin to pulsate as new shell of H begins to burn into He Begin to pulsate as new shell of H begins to burn into He It contracts and then expands It contracts and then expands A planetary nebula forms as the outer materials blow off and the inner core contracts to begin turning He into C and O. A planetary nebula forms as the outer materials blow off and the inner core contracts to begin turning He into C and O.

6. Variable Stage to Planetary Nebula A planetary nebula forms as the outer materials blows off and the inner core contracts. A planetary nebula forms as the outer materials blows off and the inner core contracts. At the center of the nebula, we can find a white dwarf. At the center of the nebula, we can find a white dwarf.

7. Planetary Nebula to White Dwarf Most common Most common Not very luminous Not very luminous High density High density Combination of pressure and high temperatures turns carbon into diamonds Combination of pressure and high temperatures turns carbon into diamonds

8. Death of the White Dwarf Becomes black dwarfs Becomes black dwarfs Mass of white dwarfs are usually between 0 and 1.4 M of the sun Mass of white dwarfs are usually between 0 and 1.4 M of the sun If Mass > 1.4 mass of dwarf then they meet the Chandrasekhar limit and begins to shrink due to gravity and pressure If Mass > 1.4 mass of dwarf then they meet the Chandrasekhar limit and begins to shrink due to gravity and pressure