The Sun, Our Star

Radius = 7x108m or 109 Earth radii Mass = 2 x 1030 kg or Size & Structure Radius = 7x108m or 109 Earth radii Mass = 2 x 1030 kg or 333,000 Earth masses

Planets, to correct relative size

Artist’s view of the Solar System Figure 7.1

Sketch of Oort cloud and Kuiper belt Figure 7.4

Distance = 1.5 x1011m from Earth Temperature Surface 5780 K or 9900 °F Core 1.5x107K or 2.7x107°F

Composition All in gas form 71% Hydrogen 27% Helium 2% other

Distance from triangulation Mass from orbits How do we know? Temp. from color Distance from triangulation Mass from orbits Interior temp. from power output

A simple way to measure the Sun’s diameter B

Energy generating in core from fusion; photons emitted Interior Energy generating in core from fusion; photons emitted Carried thru Radiative zone Bcs of density of atoms takes photon over 100,000 years

Outer region (Convection core) less dense gas (hotter) rises to suface

Hydrostatic Equilibrium Gravity (immense mass) cause Sun to want to collapse on itself Pressure from rapid motion (hot gas) of atoms balances this

Figure 11.8

Maintaining the Pressure E=mc2 Mass can be turned directly into energy Mass of size of a pill turned into energy would equal that of a nuclear bomb

Hydrogen into Helium yields a lost mass (mass deficit) Nuclear Fusion Hydrogen into Helium yields a lost mass (mass deficit) Possible because of heat & pressure of Sun

Hydrogen and helium atoms and isotopes Figure 11.10

Diagram of proton-proton chain Figure 11.11 A B C

Proton Proton chain Step 2 2 H collide to become a heavier H Step 2 The Neutron Proton collides with a single H and becomes He and emits a photon (light) and energy

Step II The Neutron Proton collides with a single H and becomes He and emits a photon (light) and energy

Step III 2 3He combine to from a 4He ,2 1H and energy

Neutrinos Difficult to measure No charge little mass Pass thru matter Tanks of heavy water miles under ground If electron is hit it emits photon

Magnetic fields Sun spots – regions that differ in color due to magnetic fields and temp Blocks heat

How magnetic fields cause sunspots Figure 11.15

Responsible for comets Solar wind Responsible for comets Loss of mass from protons & electrons that escape gravitational pull of Sun

Solar differential rotation Figure 11.22