Our Star, the Sun. Chapter Eighteen. Guiding Questions. What is the source of the Sun’s energy? What is the internal structure of the Sun? How can astronomers measure the properties of the Sun’s interior? How can we be sure that thermonuclear reactions are happening in the Sun’s core?
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The Sun’s energy is produced by hydrogen fusion, a sequence of thermonuclear reactions in which four hydrogen nuclei combine to produce a single helium nucleus
Start of hydrogen fusion process in the sun’s interior; 2 protons collide.
Step 2 in the fusion process involves a 3 protons collide.rd proton
In the final step, the end products are helium with 2 of the protons collide.
original 6 hydrogen atoms recycled.
Energy is transported by radiative diffusion from center to 0.71 solar radii
It takes 170,000 years to traverse through the body of the sun to surface.Astronomers probe the solar interior usingthe Sun’s own vibrations
Tracking the sun’s rotation with sunspots; 25 ¼ days at equator, 28.2 days at latitude 45, 34 days nearer the poles.
Solar Flare Movie
Filaments appear as prominences above solar limb
Bright areas are called Plages, sunspots
The magnetic-dynamo model suggests that many features of the solar cycle are due to changes in the Sun’s magnetic field
Coronal Quiet Region
Coronal Active Region
Coronal Mass Ejection uniformly
Coronal mass ejections send bursts of energetic charged particles out through the solar system.
Coronal mass ejection of 10 uniformly12 kg mass ( a billion tons)
22-year solar cycle uniformly
coronal mass ejection
luminosity (of the Sun)
negative hydrogen ion