Outline of The Sun (Ch. 10) (Not exactly like the book)
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Transcript of Outline of The Sun (Ch. 10) (Not exactly like the book)
I. The Solar Spectrum: Sun’s composition and surface temperature
II. Sun’s Interior: Energy source, energy transport, structure, helioseismology.
III. Sun’s Atmosphere: Photosphere, chromosphere, corona
IV. Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.
Outline of The Sun (Ch. 10)(Not exactly like the book)
Ch. 10 HW has been assigned and is due next Monday March 28
I. Solar Spectrum: Composition and Surface Temperature
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I. Solar Spectrum: How do we know the composition of the Sun?
How do we measure the composition of stars?
I. Solar Spectrum: How do we know the composition of the Sun?
What type of Spectrum is this?
How do we know this?
Name two methods to determine the temperature of stars?
Surface Temperature: approximately 5,800 K
Solar Spectrum: Composition and Surface Temperature
I. The Solar Spectrum: Sun’s composition and surface temperature
II. Sun’s Interior: Energy source, energy transport, structure, helioseismology.
III. Sun’s Atmosphere: Photosphere, chromosphere, corona
IV. Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.
Outline of The Sun (Ch. 10)
What is the source of the Sun’s energy?
a) Chemical reactions
b) Gravitational contraction
c) Nuclear fission (like in nuclear power plants)
d) Nuclear fusion
Question 1
Is it on FIRE?
Is it on FIRE?
Luminosity~ 10,000 years
Chemical Energy Content
How old is the Sun?
How old is the Sun? about 4.6x109 years
Is it on FIRE? … NO!
Luminosity~ 10,000 years
Chemical Energy Content
Is it CONTRACTING?
Luminosity
Gravitational Potential Energy
Is it CONTRACTING?
~ 25 million years
Luminosity
Gravitational Potential Energy
Is it CONTRACTING? … NO!
~ 25 million years
E = mc2
- Einstein, 1905
Is it powered by NUCLEAR ENERGY?
Luminosity~ 10 billion years
Nuclear Potential Energy (core)
Is it powered by NUCLEAR ENERGY? … YES!
Luminosity~ 10 billion years
Nuclear Potential Energy (core)
How old is the Sun? about 4.6 billion yearsAbout how many more years of fuel does the Sun have?
What is the source of the Sun’s energy?
a) Chemical reactions b) Gravitational contraction c) Nuclear fission (like in nuclear
power plants) d) Nuclear fusion
Question 1
Fission
Big nucleus splits into smaller pieces
(Nuclear power plants)
Fusion
Small nuclei stick together to make a bigger one
(Sun, stars)
4 protons one Helium nucleus + Energy
Hydrogen Fusion into Helium in the Sun’s Core
4 protons one helium nucleus + Energy
The mass of the four protons is higher than that of the helium nucleus where did the missing mass go?
Hydrogen Fusion into Helium in the Sun’s Core
4 protons one helium nucleus + Energy
The mass of the four protons is higher than that of the helium nucleus where did the missing mass go?
The mass became energy, and E=mc2 so a little mass can produce a lot of energy
Hydrogen Fusion into Helium in the Sun’s Core
Proton-proton chain is how hydrogen fuses into helium in Sun
• Sun’s interior
Core:
Energy generated by nuclear fusion
Radiation Zone:
Energy transported upward by photons
Convection Zone:
Energy transported upward by rising hot gas
In the Sun, gravity is balanced by outward pressure (due to the outflow of energy)
What if Lucius Malfoy wanted to freeze the Earth by decreasing the energy from the Sun?
Solar Thermostat
Temperature Restored
Temperature Decreases
Fusion Rate Decreases
Core compresses
What if Lucius Malfoy wanted to burn the Earth by increasing the energy from the Sun?
Solar Thermostat
Temperature Restored
Temperature Increases
Fusion Rate Increases
Core expands
In the Sun, gravity is balanced by outward pressure (due to the outflow of energy)
Helioseismology
By studying the motion of the Sun’s surface we can learn about its interior in a similar way to the study of Earthquakes.
What have we learned? How does the solar thermostat work? There is a equilibrium between gravity
and energy outflow……. How does the energy from fusion get
out of the Sun? Energy is produces in the core by nuclear
fusion and it gets radiated outward. The convection zone carries energy the rest of the way to the photosphere, where it is radiated into space as sunlight.
How do we know what is happening inside the Sun?
Helioseismology and other techniques
I. The Solar Spectrum: Sun’s composition and surface temperature
II. Sun’s Interior: Energy source, energy transport, structure, helioseismology.
III. Sun’s Atmosphere: Photosphere, chromosphere, corona
IV. Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.
Outline of The Sun (Ch. 10)
Photosphere:
Visible surface of Sun
T ~ 5,800 K
Chromosphere:
Middle layer of solar atmosphere
Corona:
Outermost layer of solar atmosphere
Solar Granulation in the Photosphere
Convection (rising hot gas) takes energy to surface
Cloud tops on Earth
Sunspots
Why do sunspots look dark? a) They are dark clouds b) They are smoke from the Sun’s
interior c) They are cooler than the rest of
the Sun’s surface d) None of the above
Question
Why do sunspots look dark? a) They are dark clouds b) They are smoke from the Sun’s
interior c) They are cooler than the rest
of the Sun’s surface d) None of the above
Question
Loops trace magnetic field lines
Blackbody radiation:
The hotter the brighter
The hotter the bluer
Why do sunspots look dark? They are cooler than the rest of
the Sun’s surface Are they redder?
Review from Ch 5
Sunspots
Visible during a total solar eclipse
Solar Chromosphere
Solar Chromosphere
Visible during a total solar eclipse
Solar Corona
Coronal mass ejections send bursts of energetic charged particles out through the solar system
I. The Solar Spectrum: Sun’s composition and surface temperature
II. Sun’s Interior: Energy source, energy transport, structure, helioseismology.
III. Sun’s Atmosphere: Photosphere, chromosphere, corona
IV. Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares.
Outline of The Sun (Ch. 10)
I. Sunspots: main indicator
II. Prominences and flares: also indicators of solar activity
III. Solar cycle: 11-year cycle
IV. Solar Activity
Charged particles streaming from Sun can disrupt electrical power grid and can disable communications satellites
Energetic particles high in Earth’s atmosphere cause auroras (aka Northern Lights)
How does solar activity affect humans?
Bursts of charged particles ejected from the Sun during periods of high solar activity can hamper radio communications,disrupt electrical power generation,and damage orbiting satellites.
Solar activity can also have a strong impact on Earth’s weather
Sunspot numbers and temperature on Earth: During the mid-to-late 1600s records indicate
a very cold period on Earth
This corresponded to a period with very few or no sunspots on the Sun