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THE SUN

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Ha Sun. Photo by Big Bear Solar Observatory. 6. Prominences. 6. 6. Corona ... Solar Wind carries away a million tons of Sun's mass each second! ... – PowerPoint PPT presentation

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Title: THE SUN


1
THE SUN
  • The star we see by day

2
Goals
  • Summarize the overall properties of the Sun.
  • What are the different parts of the Sun?
  • Where does the light we see come from?
  • The scientific method solar neutrinos.

3
The Sun, Our Star
  • The Sun is an average star.
  • From the Sun, we base our understanding of all
    stars in the Universe.
  • No solid surface.

4
Vital Statistics
  • Radius 100 x Earth (696,000 km)
  • Mass 300,000 x Earth (1.99 x 1030 kg)
  • Surface temp 5,800 K
  • Core temp 15,000,000 K
  • Luminosity 4 x 1026 Watts
  • Solar Day
  • 24.9 Earth days (equator)
  • 29.8 Earth days (poles)

5
Interior Properties
  • Core 20 x density of iron
  • Surface 10,000 x less dense than air
  • Average density Jupiter
  • Core 15,000,000 K
  • Surface 5800 K

6
Solar Interior
  • Core
  • Only place with fusion
  • Radiation Zone
  • Transparent
  • Convections Zone
  • Boiling hot

7
In The Core
  • Density 20 x density of Iron
  • Temperature 15,000,000 K
  • Hydrogen atoms fuse together.
  • Create Helium atoms.

8
Nuclear Fusion
  • 4H ? He
  • The mass of 4 H nuclei (4 protons)
  • 4 x (1.6726 x10-27 kg) 6.690 x 10-27 kg
  • The mass of He nuclei 6.643 x 10-27 kg
  • Where does the extra 4.7 x 10-29 kg go?
  • ENERGY! ? E mc2
  • E (4.7 x 10-29 kg ) x (3.0 x 108 m/s)2
  • E hc/l ? l 4.6 x 10-14 m (gamma rays)
  • So 4H ? He light!

9
Convection
  • A pot of boiling water
  • Hot material rises.
  • Cooler material sinks.
  • The energy from the pots hot bottom is
    physically carried by the convection cells in the
    water to the surface.
  • Same for the Sun.

10
Solar Cross-Section
  • Progressively smaller convection cells carry the
    energy towards surface.
  • See tops of these cells as granules.

11
The Photosphere
  • This is the origin of the 5,800 K thermal
    radiation we see.
  • l k/T k/(5800 K) ? l 480 nm (visible
    light)
  • This is the light we see.
  • Thats why we see this as the surface.

12
The Sun
Courtesy of NOAO/AURA
13
The Chromosphere
  • Hydrogen most common.
  • Brightest hydrogen line Ha.
  • Chromosphere color

14
Ha Sun
Photo by Big Bear Solar Observatory
15
Prominences
16
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17
Corona
  • The hot, low density, gas at this altitude emits
    the radiation we see as the Corona.
  • 1,000,000 km
  • But corona very faint compared to photosphere.

18
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19
Solar Wind
  • At and above the corona
  • Gas is very hot
  • Very energetic
  • Like steam above our boiling pot of water, the
    gas evaporates.
  • Wind passes out through Coronal Holes
  • Solar Wind carries away a million tons of Suns
    mass each second!
  • Only 0.1 of total Suns mass in last 4.6 billion
    years.

20
Sunspots
  • 11-year sunspot cycle.
  • Center Umbra 4500 K
  • Edge Penumbra 5500 K
  • Photosphere 5800 K

21
Magnetic fields and Sunspots
  • At kinks, disruption in convection cells.
  • Sunspots form.

22
Magnetic fields and Sunspots
  • Where magnetic fields pop out of Sun, form
    sunspots.
  • Sunspots come in pairs.

23
Solar Cycle
  • Increase in solar wind activity
  • - Coronal Mass Ejections
  • Increase in Auroral displays on Earth
  • Increase in disruptions on and around Earth.

Courtesy of SOHO/LASCO/EIT consortium.
24
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25
Aurora
  • The solar wind
  • passes out
  • through the
  • Solar System.
  • Consists of electrons, protons and other charged
    particles stripped from the Suns surface.
  • When charged particles and magnetic fields
    interact light!

26
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27
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28
2003 CME
Oklahoma 10/29/2003
Credit E. Woldt
29
Solar Neutrino Problem
  • We observe
  • Suns luminosity (total light radiated).
  • We hypothesize
  • 4H ? He light neutrinos
  • We can test
  • Observe number neutrinos reaching Earth
  • Does our test agree with hypothesis?
  • No

30
What to Do?
  • For 30 years
  • Theorists certain of nuclear reaction.
  • Observers positive of observations.
  • Detected only 1/3 the hypothesized neutrinos.
  • What to do?

31
Neutrino Flavors
  • 3 types of neutrinos
  • Electron neutrino
  • Tau neutrino
  • Muon neutrino
  • Nuclear reactions produce only electron neutrino.
  • Previous detectors only detected electron
    neutrinos.

32
Neutrino Fluctuations
  • New detector (2002) gives number of all three
    flavors.
  • Total number agrees with number predicted in core
    of Sun.
  • Conclusion
  • Nuclear hypothesis is correct.
  • Neutrinos change flavor.
  • Neutrinos have mass (used to be thought
    massless).
  • Problem solved ? new science discovered.

33
Homework 6
  • Due Tuesday 2/3
  • Read Exoplanet articles.
  • (Homework is to read the articles and website.)
  • Website is http//www.howstuffworks.com/planet-hu
    nting2.htm
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