Have You Learned Anything?

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Have You Learned Anything?
http//aspire.cosmic-ray.org/labs/star_life/hr_int
eractive.html
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Life of the Sun
What is wrong with this schematic? (not an HR
Diagram)
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..
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Star Party
Star Party
Timing Colors Populations
Actions
Transportation
Fuels
End States
1 hour 1 billion years
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Stellar Evolution The Star Party

• Characters
• The Mellow Surfer Dude
• Tom Hanks
• John Candy
• Main Sequence gt 90 of a stars life
• Behavior set by MASS
• stars do NOT evolve along the main sequence
• Partners 50 binaries, triples, quadruples
• bigger stars have more partners

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HR Diagram Entry
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Mellow Surfer Dude

• Transportation
• Time in Transit
• Time at Party
• Fuels

1 hour 42 days H
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M Star Evolution
live far longer than current age of the Universe
no red giant phases
turn into blue dwarfs
then white dwarfs
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Tom Hanks

• Transportation
• Time in Transit
• Time at Party
• Fuels

3 minutes 10 hours H He
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G Star Evolution
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Planetary Nebula
Planetary Nebula
WD 200,000 K
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John Candy

• Transportation

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John Candy
John Candy
Transportation Time in Transit Time at
Party Fuels
4 seconds 36 seconds H He C O Ne Mg
Si Fe
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O Star Evolution
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1. Proton-Proton Chain
3 Reactions I. 1H 1H ? 2H
positron neutrino energy
positron electron ? gamma rays
II. 2H 1H ? 3He energy III.
3He 3He ? 4He 1H 1H
energy dominates below 15 million K
2 more branches branch 2 He Be Li
Be dominates 1525 million
K branch 3 Be B Be He
dominates above 25 million K
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2. CNO Cycle
dominates in stars gt 1.1 Msun Net Result 12C
4 1H ? 12C 4He stuff
energy C is the catalyst N and O made along
the way C ? N ? C ? N ? O ? N ? higher T
needed than for p-p chain 4He production
rates 15 million K 98 p-p 20
million K 50 p-p 25 million K 10
p-p the rest is via CNO
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3. Triple Alpha Process
Net Result 3 4He ? 12C stuff
energy
Sun on Horizontal Branch temperature
required is 100 million K
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4. Helium Capture
stars gt 8 Msun balance of Helium Capture vs.
gamma ray photodisintegration
to Si
0.9x109 K 2.3x109 K 1.7x109 K
Fe has highest binding energy of all elements Ni
is made, but it is unstable ? Fe
4.1x109 K
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John Candys Fuels
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John Candys Guts
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Early Mass Loss
Early Mass Loss
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5. s - process
Slow Buildup 56Fe n ? 57Fe add more
n unstable decays to
59Co all the way to 209Bi
highly evolved massive stars Cu 29 Zn
30 Kr 36 Ag 47 Pt 78 Au 79 Bi 83
BLING PROCESS !
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Supernova Mass Loss
Supernova Mass Loss
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6. r - process
Rapid Buildup 209Bi n ? radioactive
elements trying to decay
neutrons JAMMED into nuclei just after
supernova explosion U 92 Pu 94
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Supernova (Type II)

• Progenitor one massive ( gt 8 Msun) star with Fe
  core
• Observe 10 billion X brighter in hours
• in months light output Suns entire life
• lots of H in spectrum
• light curve has spike plateau months later
  (cooling envelope)
• Process 1. big star runs out of fuel
• 2. gravity begins to collapse core
• 3. high energy photons blast heavy nuclei
• 4. core cools as nuclei shredded (lots of
  energy required)
• 5. collapse accelerates only photons, p,
  e, n
• 6. p and e crushed into n (neutrinos
  released)
• 7. core overcrush beyond n degeneracy
  pressure
• 8. BOUNCE EXPLOSION shock wave!

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Supernova (Type II)

• in one second,
• core collapse undoes
• previous 10 million years of work

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SN 1987A
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Stellar Generations
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Element Manufacture
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Universal Soup
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Star Party Summary

• Population to Main Seq on Main Seq end
  ............
• M (Dude) 7000 1 billion yrs 1 trillion
  yrs fizzle
• G (Tom) 600 50 million
  yrs 10 billion yrs RG/PN/WD
• O (John) 1 1 million yrs 10 million
  yrs BOOM!
• (gt 8 Msun)
• 10000 people at the party

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End Points
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Stellar Evolution Models
http//www.astro.uni-bonn.de/javahrd
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