1. Energy Production in the Sun Physics 113 Goderya Chapter(s): 8 Learning Outcomes:

2. o F = 9/5( o K) -459.4 o F = 9/5( o C) + 32 o K = 273 + o C o C o K o F 0 32 273 100212373 -100173 -148 Temperature Scales

3. Energy produced in the Sun –600,000,000 tons of hydrogen every second –100 million nuclear bombs every heartbeat

4. Density and Temperature of the Sun

5. Energy flow in the Sun Radiative zone Convective zone

6. Gravity and Sun Gravity of Sun attracts the matter, What keeps the sun from collapsing onto itself?

7. Gas Pressure and Temperature Pressure = density x temperature x constant

8. Hydrostatic Equilibrium The tug War Who is the winner?

9. What kind of fuel can give such high temperatures ? Nuclear Fusion

10. The Proton- Proton (p-p) Chain E = mc 2

11. Converting Mass into Energy 4 H atoms = 6.693 x 10 -27 kg -1 He atom = 6.645 x 10 -27 kg _______________________ Mass Lost = 0.048 x 10 -27 kg 0.7% of mass converted to energy E = mc 2 = (0.048 x 10 -27kg ) (3 x 10 8 m/s) 2 = 4.3 x 10 -12 joule Lights up a 10-watt bulb for a one-half of a trillionth of a second 10 7 times larger than burning in a chemical reaction E = mc 2

12. Comparing fusion with burning E = mc 2 = (0.007kg) (3 x 10 8 m/s) 2 = 6.3 x 10 14 joule Converting 1 kg of Hydrogen into Helium 20,000 metric tons of coal (2 x 10 7 kg) is needed to produce this much energy

13. Lifetime of the Sun Luminosity of the Sun 3.9 x 10 26 joules per second 600 billion kg every second 3.9 x 10 26 joules per second _______________________ 6.3 x 10 14 joules per kilogram = 6 x 10 11 kilograms per second Mass of the Sun = 1.9891 x 10 30 kg 1.9891 x 10 30 kg __________________ 6 x 10 11 kg per second = 3.3 x 10 18 second 3.3 x 10 18 seconds _______________________ 3.15 x 10 7 seconds per year = 1.05 x 10 11 years or

14. Energy Production Energy generation in the sun (and all other stars): Nuclear Fusion = fusing together 2 or more lighter nuclei to produce heavier ones. Nuclear fusion can produce energy up to the production of iron; For elements heavier than iron, energy is gained by nuclear fission. Binding energy due to strong force = on short range, strongest of the 4 known forces: electromagnetic, weak, strong, gravitational

15. So How Long will the Sun Live? T Life = 10 10 /M sun 2 If M sun = 1, then T Life = 10 10 years

16. Helioseismology The solar interior is opaque (i.e. it absorbs light) out to the photosphere.  Only way to investigate solar interior is through Helioseismology = analysis of vibration patterns visible on the solar surface: Approx. 10 million wave patterns!