The Sun: Our Star

1
The Sun Our Star
2
Hydrostatic Equilibrium
3
Structure of the Sun
4
More About the Sun
5
Helioseismology

• Vibrations on the surface depend on the density
  and temperatures in the interior of the Sun

6
Nuclear Reactions
7
Overcoming Electrostatic Repulsion
8
Nuclear Fusion Energy for Sun
9
Fusion in the Core of the Sun
10
Energy from Fusion

• Proton mass 1.6726 10-27 kg
• Four protons 6.690 10-27 kg
• One helium-4 nucleus 6.643 10-27 kg
• Two positrons 0.0018 10-27 kg
• Neutrino mass even smaller
• Mass converted per reaction E mc24.5 10-29
  kg E 4 10-12 Joules
• Less than a percent (0.7) of mass

11
Core Pressure Balance
12
Testing the Solar Model
13
Neutrinos from the Sun
14
Radiation Zone

• Photons random walk through many layers of the
  Sun

15
Convection Zone

• The gas in the convection layers bubble like
  boiling water
• Photons of light are aided in their journey to
  the outer layers of the Sun

16
Granules
17
Granules
18
Granulation and Sunspots

• The brighter features are hotter due to the laws
  of thermal radiation
• What does this imply about the Sunspot?
• Granules are evidence of convection below the
  photosphere

19
Chromosphere and Corona
20
Magnetic Fields and Charged Particles
21
Sunspots and Magnetic Fields

• Sunspots are cold spots on the photosphere
• Sunspots arestorms of magnetic field
• Prominencesand flares are connected tosunspots

22
Prominences
23
Solar Flare
24
The Active Sun X-ray Image
25
Sunspot Cycle

• Number of sunspotspeaks every 11 years
• Location of sunspotsshifts during cycle
• Solar cycle is really22 years magnetic field
  is reversed in the E-W direction

26
Babcock Model
27
Solar Activity Affects Earth
28
Solar Activity Affects Earth