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© 2010 Pearson Education, Inc.
Chapter 14Our Star
© 2010 Pearson Education, Inc.
Why does the Sun Shine?
© 2010 Pearson Education, Inc.
Is it on FIRE?
© 2010 Pearson Education, Inc.
Is it on FIRE?
Luminosity~ 10,000 years
Chemical energy content
© 2010 Pearson Education, Inc.
Is it on FIRE? …NO!
Luminosity~ 10,000 years
Chemical energy content
© 2010 Pearson Education, Inc.
Is it CONTRACTING?
Insert TCP 6e Chapter 14 opener
© 2010 Pearson Education, Inc.
Is it CONTRACTING?
Luminosity
Gravitational potential energy~ 25 million years
© 2010 Pearson Education, Inc.
Is it CONTRACTING?...NO!
Luminosity
Gravitational potential energy~ 25 million years
© 2010 Pearson Education, Inc.
Why does the Sun shine?
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Weight of upper layers compresses lower layers.
Insert TCP 6e Figure 14.1
© 2010 Pearson Education, Inc.
Gravitational equilibrium:
There is a balance between the outward fusion pressure and the inward pressure, due to gravity.
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What is the Sun’s structure?
Insert TCP 6e Figure 14.3
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Solar wind:
A flow of charged particles from the surface of the Sun
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Corona:
Outermost layer of solar atmosphere and seen only during a total solar eclipse.
~1 million K
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Chromosphere:
Middle layer of solar atmosphere and seen only during a total solar eclipse.
~ 104–105 K
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Photosphere:
Visible surface of Sun
~ 6000 K
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Convection Zone:
Energy transported upward by rising hot gas
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Radiation Zone:
Energy transported upward by photons
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Core:
Energy generated by nuclear fusion
~ 15 million K
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Clicker QuestionWhat is the surface we see?
A. coronaB. photosphereC. chromosphereD. solar wind
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is the surface we see?
A. coronaB. photosphereC. chromosphereD. solar wind
© 2010 Pearson Education, Inc.
Clicker QuestionWhat layer is the hottest?
A. coronaB. photosphereC. chromosphere
© 2010 Pearson Education, Inc.
Clicker QuestionWhat layer is the hottest?
A. coronaB. photosphereC. chromosphere
© 2010 Pearson Education, Inc.
Clicker QuestionWhat layer is the coolest?
A. coronaB. photosphereC. chromosphere
© 2010 Pearson Education, Inc.
Clicker QuestionWhat layer is the coolest?
A. coronaB. photosphereC. chromosphere
© 2010 Pearson Education, Inc.
How does nuclear fusion occur in the Sun?
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Fission
Big nucleus splits into smaller pieces.
(Example: nuclear power plants)
Fusion
Small nuclei stick together to make a bigger one.
(Example: the Sun, stars)
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High temperatures enable nuclear fusion to happen in the core.
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The Sun releases energy by fusing four hydrogen nuclei into one helium nucleus.
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The proton–proton chain is how hydrogen fuses into helium in Sun.
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IN4 protons
OUT4He nucleus
2 gamma rays2 positrons2 neutrinos
Total mass is 0.7% lower.
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Proton-Proton Chain in Gory Detail
Step 1: 1H1 + 1H1 --> 2H1 + e+ + 1H1 is a hydrogen nucleus - subscript is the number of protons
in nucleus, superscript is the number of protons + neutrons in the nucleus. Hydrogen nucleus has 1 proton, 0 neutrons.
2H1 is a deuterium nucleus (hydrogen isotope) with 1 proton and 1 neutron in nucleus.
e+ is a positron or antiparticle of the e-. When e+ and e- meet,
e+ + e- __ > 2 two gamma rays are producedis a neutrino and helps to carry away energy.
Step 2: 1H1 + 2H1--> 3He2 +
3He2 is a helium isotope, is a gamma ray.
Step 3: 3He2 + 3He2 --> 4He2 + 1H1 + 1H1 4He2 is ordinary or ‘balloon’ helium.
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Clicker QuestionWhat is e+?
A. electronB. positronC. NeutronD. protonE. neutrino
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is e+?
A. electronB. positronC. NeutronD. protonE. neutrino
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is 2H1?
A. gamma rayB. helium nucleusC. deuterium nucleusD. ordinary hydrogen nucleus
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is 2H1?
A. gamma rayB. helium nucleusC. deuterium nucleusD. ordinary hydrogen nucleus
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is ?
A. gamma rayB. positronC. NeutronD. protonE. neutrino
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is ?
A. gamma rayB. positronC. NeutronD. protonE. neutrino
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is ?
A. gamma rayB. positronC. NeutronD. protonE. neutrino
© 2010 Pearson Education, Inc.
Clicker QuestionWhat is ?
A. gamma rayB. positronC. NeutronD. protonE. neutrino
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