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Chapter 20 part 1: Star death: –0.4 - 4 M  Carbon White dwarfs –> 4 M  Supernova SN1987A Neutrinos –Supernovae involving white dwarfs –Supernova remnants.

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Presentation on theme: "Chapter 20 part 1: Star death: –0.4 - 4 M  Carbon White dwarfs –> 4 M  Supernova SN1987A Neutrinos –Supernovae involving white dwarfs –Supernova remnants."— Presentation transcript:

1 Chapter 20 part 1: Star death: –0.4 - 4 M  Carbon White dwarfs –> 4 M  Supernova SN1987A Neutrinos –Supernovae involving white dwarfs –Supernova remnants

2 Evolution of a 1 M  star

3 Structure of an old AGB star

4 Example: H-R diagram of M55 Cluster at least 13 billion years old Low mass stars still on main-sequence More massive stars on red-giant branch or horizontal branch Most massive stars remaining are ascending the asymptotic giant branch.

5 Convection and dredge-ups Convection can reach core of moderate size stars as they age. This can “dredge up” heavy elements from core. This process can enrich the interstellar medium with C, N and O.

6 Final stages of the Sun’s life

7 Planetary nebulae

8 White dwarfs A white dwarf is the core of a moderate mass star. First observed in 1862. Does not shrink as it cools. –Supported by degenerate electron pressure. Incredibly dense –10 9 kg/m 3 (million times denser than water)

9 Mass-radius relationship The more massive a white dwarf the smaller it is. Limit to this relationship is called Chandrasekhar limit. –1.4 M 

10 From giant to dwarf

11 White dwarf cooling curves

12 The Sun’s entire life

13 Massive stars

14


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