Density of the Suns layers in order

Image of total eclipse in north Queensland Australia - courtesy Joe. Michna - note solar flares at bottom

Layers/Regions:

Core:

• Central energy producing region
• Thermonuclear fusion occurs here.
• Energy transport by radiation. 
• Temperature: ~16 x 106 K
• Density: ~160 g/cm3 

• large region of interior photons scattered on the way to the solar surface.
• Temperature: ~8 x 106 K 
• Density: ~20 g/cm3

Convective Zone: Transition region between interior
  and surface. Energy transport by convection.
  Temperature: ~5 x 105 K
  Density: ~0.01 g/cm3

Photosphere: Visible surface of the Sun.
  Convective "bubbles" from below visible
  Granulation. Location of Sunspots.
  Temperature: ~5.8 x 103 K
  Density: ~4 x 10-7 g/cm3

Chromosphere:
Beginning of solar "atmosphere".

• Location of prominences and solar flares.
• Temperature: ~5 x 104 K
• Density: ~8 x 10-8 g/cm3
• Transition Region: Region between corona and chromosphere.
• Temperature changes from ~50,000 K in chromosphere to ~2 x 106 K in corona over
• a few tens of kilometers!!!!
• Corona: Hot, thin, large solar "atmosphere". Coronal holes are source of the solar
• wind.
• Temperature: ~2 x 106 K
• Density: ~1 x 10-14 g/cm3

Granulation:   Provide evidence of convection below solar surface

 Diagram of convection.   Sunspots:

Regions of intense magnetic fields.
Temperature ~ 4200 K cooler than photosphere, which makes them appear as dark spots.
Can be used to measure solar rotation (25 days at equator, 31 days at poles).
Umbra - dark inside, Penumbra - lighter outside

  Spicules:
  Chromosphere contains many dark, brush-like spikes that protrude upward.  These are called spicules.They are "jets" of gas surging away from the sun at 20 km/s.

  Prominences/Solar Flares
:

  Huge, arching columns of gas often appearing above sunspots. Prominences are regions along a magnetic field line where conditions are right for light to be emitted.

Occasionally, kinks and stresses occur on magnetic field lines discharging amounts  of energy (known as Solar Flares). The amount of energy released is equivalent to a 2 billion megaton bomb. Flares release large numbers of particles into the corona.

Energy Transport:

• 1.Radiative Transport


• Energy is transported by photons.
• Energy loss by scattering and absorption by atoms.
• Very efficient mechanism in stars (also efficient on cloudless evenings very chilly nights).


• 2.Convective Transport


• Energy transported by bulk motion of mass.
• Important mechanism in stars.
• Very poorly understood process.


• 3.Conductive Transport


• Energy transport by atoms colliding with one another, gaining and releasing energy.

• Energy:
• Examples of Energies:
• Energy to lift a sheet of paper 1 cm: ~ 1 erg
• Chemical energy in a barrel of oil: ~ 1017 ergs
• Nuclear energy in a gram of water: ~ 7 x 1019 ergs
• Total energy emitted by Sun in its lifetime: ~ 1050 ergs
• Total energy emitted by single supernova: ~ 1051 ergs

1.Gravitational Energy:
  Energy resulting from the motion of matter when interacting with other matter.
2.Chemical Energy:
  Energy resulting from, a change in the electron structure of atoms when bonding with other atoms. "Burning".
    3.Nuclear Energy:
  Energy resulting from changes in the nuclear structure of atoms.

Gravitational Energy As A Source Of Solar Energy:

Total gravitational energy ÷ Luminosity = How long sun could be powered.
  (1 × 1048 ergs) ÷ (4 × 1033 ergs) = Could power the sun for about 100 million years.

  Chemical Burning As A Source Of Solar Energy:
  Total chemical energy ÷ Luminosity = How long sun could be powered.
  (1 × 1046 ergs) ÷ (4 × 1033 ergs) = Could power the sun for about 10,000 years.

  Until the late 1800s, gravitational energy was thought to be sufficient, since it was not thought that the Universe was that old. However, for two reasons it was later thought that something more than gravitational energy powered the sun: Darwin (1809-1882): Theories of evolution required much longer than 108 years for evolution to proceed.  Geological dating of rocks indicated that the Earth was several x 109 years old.

So What Powers The Sun?
  Einstein, getting energy from hydrogen fusion, came up with the following equation that explains it all:

 E = mc2
 E = Energy,    m = mass,   c = speed of light

Fundamental Structure Of The Atom:

    The Nucleons:
P+   Proton  (charge: +,  mass: 1.67 × 10-24 g)
    n    Neutron (charge: Ø, mass: 1.67 × 10-24 g)
    The Electron:
    e-   Electron (charge: -, mass: 9 × 10-28 g)

The Proton-Proton Chain:   Nuclear Fusion:

  High Temperatures Are Needed For Fusion. Why? Recall that like charge repel.

High temperatures (energy) are required in order to overcome this repulsion.Actual details require descriptions provided by Quantum Mechanics.   Temperature required for the p-p chain:    T ~ 107 K

Temperature is found in the Sun's core, where density is ~ 160 g/cm3 . Even at this density, reaction probability is very low. Single proton takes ~ 7 x 109 years before reacting. Large number of protons make up for low probability.

What is the density of each layer of the Sun?

What layer of the Sun has the highest density?

What are the 7 layers of the Sun in order?

Which layer of the Sun is the least dense?