Lecture 5: The Solar Interior- Hotter than a Green Chile Cheeseburger

"Abandon Hope, All Ye Who Enter Here"
Dante, Inferno

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Date: February 7, 1995
Reading Assignment: pp. 380-389

Description : solar interior, nuclear fusion, neutrons, oscillations, and convection

Objectives

be able to describe the proton proton chain and why it is important

be able to explain what the solar neutrino mystery is and why it is important and what might solve this mystery

be able to explain how solar oscillations and the GONG network probe the Sun's interior

be able to describe how energy travels from the Sun's interior to its photosphere, and then to Earth

be able to describe why and how computer models are used to understand the solar interior

Lecture Outline

Slide # 1: The Solar Interior

Hotter than a Green Chile Cheeseburger

Slide # 2: The Sun

describe the physical characteristics

distinguish between interior and atmosphere

identify characteristics of the atmosphere

describe limb darkening

describe convection and radiative transfer

discuss sunspots and the sunspot cycle

distinguish between prominences, flares, and the solar wind

Slide # 3: Coronal Heating (GRAPHICS)

the temperature of the Corona is much higher than the chromosphere

Slide # 4: Coronal Heating

energy is probably transfer to the Cornoa through magnetic fields

Slide # 5: The Solar Corona (GRAPHICS)

hot outer region of solar atmosphere

Slide # 6: Sunspot Image (GRAPHICS)

closeup of a sunspot group

Slide # 7: Sunspot Pairs (GRAPHICS)

magnetic fields connect sunspot pairs

Slide # 8: Solar Activity

Prominences

10 times the size of Earth

active prominences form in hours

quiescent prominences form in days

Solar Flares

very energetic

100 million K temperature

form in minutes

Slide # 9: Prominences (GRAPHICS)

Skylab 1973- ultraviolet image

Slide # 10: Cycles on the Sun

Sunspot Cycle

11 year cycle of the position and number of Sunspots

Solar Cycle

22 year cycle of the magnetic field of the Sun

Slide # 11: Solar Magnetic Field

strongest in Sunspot regions

heats the Solar Corona

linked to Solar Activity

prominences and flares

follows a 22 years cycle

formed in Solar Convection Zone

Slide # 12: Magnetograph of the Sun (GRAPHICS)

January 28, 1995

Slide # 13: X-ray Image of the Sun (GRAPHICS)

January 28, 1995

Slide # 14: Solar Activity

the amount of flares and prominences is tied to the Solar Cycle

lots of sunspots usually means lots of active regions

Slide # 15: Two Types of Excitation

Collisionally

atoms collide with other atoms

Radiatively

photons hit the atom

only photons of the correct energy excite atoms

Slide # 16: Solar Interior (GRAPHICS)

cross sectional view

Slide # 17: Solar Interior (GRAPHICS)

cross sectional view

Slide # 18: How do you "model" a star?

laws of physics

computer simulations

matches to observed data

Slide # 19: Star Modeling- Laws of Physics

hydrostatic equilibrium

energy transport

energy generation

mass continuity

Slide # 20: Hydrostatic Equilibrium (GRAPHICS)

a balance between pressure and gravity

Slide # 21: Hydrostatic Equilibrium

most stars are in hydrostatic equilibrium

they are not expanding or contracting

gravity and pressure are balanced

Slide # 22: Energy Transport

energy is created in the core

travels to the photosphere in two ways

convection

radiation

the process of moving energy is called energy transport

Slide # 23: Energy Transport - Convection

energy is transferred through moving matter

hotter material rises

cooler material sinks

occurs in the Solar Convection Zone

Slide # 24: Energy Transport - Radiation

energy is transported by photons

photons move, not the gas

photons may be deflected, but they carry the energy

occurs in the Solar Core and Interior

Slide # 25: Energy Transport - Radiation (GRAPHICS)

photons carry the energy

Slide # 26: What powers the Sun?

only understood in this century

no obvious answer until 1930's

Slide # 27: Historical Overview of Sun's Power

chemical reactions

something is burning or reacting

gravitational collapse

compression from gravity generates heat

gravity and chemical reaction can produce enough power, but the cannot sustain

Slide # 28: Nuclear Energy

nuclear fusion

combines small atoms to make heavier atoms

examples: the Sun, the Hydrogen bomb

nuclear fission

breaks large atoms into smaller atoms

examples: nuclear power plants, radioactive decay, Atomic bombs

Slide # 29: Energy Generation - Nuclear Fusion (GRAPHICS)

hydrogen fuses into helium

energy is released

Slide # 30: The Proton-Proton Chain

hydrogen cannot fuse directly into helium

the chances of 4 protons hitting at the same time are essentially zero

one set of reactions which lead to hydrogen fusing into helium is called the P

Slide # 31: Nuclear Fusion (GRAPHICS)

symbols of nuclear fusion

Slide # 32: The Proton-Proton Chain (GRAPHICS)

hydrogen into helium in 3 easy steps

Slide # 33: The Proton-Proton Chain (GRAPHICS)

steps to nuclear fusion

Slide # 34: Constellation Corner (GRAPHICS)

The Constellation de Jour

Slide # 35: Cassiopeia (GRAPHICS)

Fairfax - Feb 1 - 10pm - N - 6.0

Slide # 36: Cepheius (GRAPHICS)

Fairfax - Feb 1 - 10pm - N - 5.0

Slide # 37: Cepheius (GRAPHICS)

Fairfax - Feb 1 - 10pm - N - 4.0

Slide # 38: Cepheius (GRAPHICS)

Fairfax - Feb 1 - 10pm - N - 4.0

Slide # 39: Mass Continuity

mass continuously increases from the core of the star to the surface

there is no such thing as negative mass

not surprising, but essential for computer models

Slide # 40: Laws of Physics

hydrostatic equilibrium

energy transport

energy generation

mass continuity

Slide # 41: Computer Simulations

numerical methods are used to solve complex equations

computers are very very good at numerical calculations

Slide # 42: Computer Simulations (GRAPHICS)

information presented graphically

Slide # 43: Solar Interior (GRAPHICS)

cross sectional view

Slide # 44: Testing the Solar Models

Helioseismology

Solar Neutrino Astronomy

Slide # 45: Helioseismology

the Sun is a large ball of gas

convection inside the Sun creates waves which move across the Sun's surface

the characteristics of these waves depend on the properties of the interior

Slide # 46: Helioseimology

similar to Seismology on Earth

oscillations of the surface map the interior

the GONG telescopes maps Solar Oscillations

Slide # 47: Helioseismology

almost all of the results from Helioseismology can be reproduced by computer m

observations have been used to determine which programs are working the best

Slide # 48: New Results in Helioseismology (GRAPHICS)

rotation curve of the Sun

Slide # 49: Neutrino Astronomy

Neutrinos are associated with some Nuclear reations

very low mass

no electrical charge

Neutrinos do not interact strongly with matter

most neutrinos pass directly through the Earth

Slide # 50: Neutrino Astronomy (GRAPHICS)

formed in Solar core

> 99.99 percent of Neutrinos pass through the Sun without interacting

some Neutrinos pass through the Earth

Slide # 51: Neutrino Astronomy

a very very small number of Neutrinos should interact with normal matter

neutrino astronomy measures the number of Neutrinos coming from the Sun

Slide # 52: A Neutrino Telescope (GRAPHICS)

Solar Neutrino Telescope

Slide # 53: The Results

only about 1/3 of the neutrinos predicted by computer models are detected

this is NOT easily explained

Slide # 54: New Results

Washington Post - 2/6/95

Neutrinos might have mass and change forms

suspected for many years as a solution

preliminary confirmation

EXPLAINS SOLAR NEUTRINO RESULTS!