Energy Production in the SunPhysics 113 Goderya

Chapter(s): 8Learning Outcomes:

• o F = 9/5(o K) -459.4

• o F = 9/5(o C) + 32

• o K = 273 + o C

o Co K o F

0 32273

100 212373

-100173 -148

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 = mc2

Converting Mass into Energy

4 H atoms = 6.693 x 10-27kg-1 He atom = 6.645 x 10-27kg_______________________Mass Lost = 0.048 x 10-27kg

0.7% of mass converted to energy

E = mc2 = (0.048 x 10-27kg) (3 x 108 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

107 times larger than burning in a chemical reaction

E = mcE = mc22

Comparing fusion with burning

E = mc2 = (0.007kg) (3 x 108 m/s)2 = 6.3 x 1014 joule

Converting 1 kg of Hydrogen into Helium

20,000 metric tons of coal (2 x 107 kg) is needed to producethis much energy

Lifetime of the SunLuminosity 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 1014 joules per kilogram= 6 x 1011 kilograms per second

Mass of the Sun = 1.9891 x 1030kg

1.9891 x 10 30 kg__________________6 x 1011 kg per second= 3.3 x 1018 second

3.3 x 10 18 seconds_______________________3.15 x 107 seconds per year= 1.05 x 1011 years

or

Energy ProductionEnergy 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 = 1010 /Msun2

If M sun = 1, then T Life = 1010 years

HelioseismologyThe 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!