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

o F = 9/5( o K) o F = 9/5( o C) + 32 o K = o C o C o K o F Temperature Scales

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

Density and Temperature of the Sun

Energy flow in the Sun Radiative zone Convective zone

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

Gas Pressure and Temperature Pressure = density x temperature x constant

Hydrostatic Equilibrium The tug War Who is the winner?

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

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

Converting Mass into Energy 4 H atoms = x kg -1 He atom = x kg _______________________ Mass Lost = x kg 0.7% of mass converted to energy E = mc 2 = (0.048 x kg ) (3 x 10 8 m/s) 2 = 4.3 x 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

Comparing fusion with burning E = mc 2 = (0.007kg) (3 x 10 8 m/s) 2 = 6.3 x 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

Lifetime of the Sun Luminosity of the Sun 3.9 x joules per second 600 billion kg every second 3.9 x joules per second _______________________ 6.3 x joules per kilogram = 6 x kilograms per second Mass of the Sun = x kg x kg __________________ 6 x kg per second = 3.3 x second 3.3 x seconds _______________________ 3.15 x 10 7 seconds per year = 1.05 x years or

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

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

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!