Planetary Nebula Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf As the outer layers are lost, inner layers gradually revealed We see the inside of the star Until nearly the end, the inside is unaffected Still burning fuels at the same rate As the inner layers are revealed, how does the star move on the H-R diagram? A) LeftC) UpE) Left and Up B) RightD) DownF) Right and Down Dying Stages – Low Mass Stars

Planetary Nebula on H-R diagram Star moves to left on H-R Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf Core Helium- Burning Double Shell- Burning

Star becomes so hot it radiates in ultraviolet Visible luminosity goes down Ultraviolet light bumps electrons up in gas surrounding the star Electrons fall back down – make visible light - colors Planetary Nebula Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf What would the spectrum of a planetary nebula be like? A) A dark line spectrum B) A bright line spectrum C) A continuous (black body) spectrum

Double Shell- Burning Planetary Nebula Double Shell Burning   White Dwarf Hydrogen Helium Carbon/Oxygen Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf

Abell 39 Planetary Nebulae

Ring NGC 6751 Planetary Nebulae

Hourglass Eskimo Planetary Nebulae

NGC 2440 Helix Dumbbell Planetary Nebulae

Egg Planetary Nebulae

Spirograph M2-9 Cat’s Eye Planetary Nebulae

White Dwarfs Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf Burnt out Carbon/Oxygen core Gradually cools and fades Why can’t two objects be at the same place at the same time? How come you can’t walk through walls? A) Electromagnetic forces B) Strong nuclear forces C) Gravitational forces D) Quantum mechanics

Degeneracy Pressure Quantum mechanics Certain types of particles: can’t have two of same type in same place Electrons, neutrons, protons When you push them together, you get pressure Greatest for electrons P  n 5/3 /m It is independent of temperature As white dwarf cools, no change in size White dwarf has constant radius, falling temperature Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf

Star moves to right and down on H-R White Dwarfs Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf Core Helium- Burning Double Shell- Burning

Stars have lost mass. Sun will end as about 0.6 M Sun 8 M Sun will end as about 1.4 M Sun The more massive they are, the smaller they are Very dense! Very small! (Earth sized) Maximum mass - Chandrasekhar mass is 1.4 M Sun. Any star starting with > 8 M Sun cannot end as a white dwarf White Dwarf Size and Mass Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf

White Dwarf Size and Mass Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf

Initial vs. Final Size Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf

White Dwarf Size Molecular Cloud Protostar Main Sequence Red Giant Core Helium- Burning Double Shell- Burning Planetary Nebula White Dwarf

H-R tracks for White Dwarfs

Summary of Stages: < 8 Solar Masses Core Helium- Burning Double Shell- Burning

Summary of Stages: < 8 Solar Masses Stage Core ActivitySizeS. Temp. Molecular Cloud (not a star)Huge Protostar Hydrogen LargeCool Main Sequence Hydrogen burningSmallHot Red Giant Helium ashLargeCool Core Helium-Burning Helium burningMediumHot Double Shell-Burning Carbon/Oxygen ashLargeCool Planetary Nebula (not a star)Huge White Dwarf Dead C/O coreTinyHot