Charles Hakes Fort Lewis College1

Charles Hakes Fort Lewis College2 Doppler/ Sunspots/ Interior

Charles Hakes Fort Lewis College3 Lab notes “Sunspots” lab discussion today after class. Telescope Lab next week. Constellation Lab coming up. Picture How to find it Interesting objects History/Mythology Participation

Charles Hakes Fort Lewis College4 What is the speed of light? A) 3x10 5 B) 3x10 8 C) Not enough information in A or B.

Charles Hakes Fort Lewis College5 The Doppler Effect One more tool…

Charles Hakes Fort Lewis College6 A source of light is approaching us at 3,000 km/s. All its waves are: A) Red shifted by 1% B) Blue shifted by 1% C) Not affected, as c is constant in all reference frames. D) Red shifted out of the visible into the infrared E) Blue shifted out of the visible into the ultraviolet

Charles Hakes Fort Lewis College7 Figure 2.22 Doppler Effect

Charles Hakes Fort Lewis College8 The Doppler Effect A “red” shift to longer wavelengths occurs when an object moves away from you. A “blue” shift to shorter wavelengths occurs when an object moves towards from you. Transverse velocities have no effect.

Charles Hakes Fort Lewis College9 The Doppler Effect A Note on police radar Pulses are emitted, and the change in frequency of the echo pulse is what is measured - NOT a shift in the wavelength of the return pulse.

Charles Hakes Fort Lewis College10 Figure 2.23 Doppler Shift For EM waves (astronomical purposes) wave speed = c c = 3 x 10 8 m/s

Charles Hakes Fort Lewis College11 A source of light is approaching us at 3,000 km/s. All its waves are: Discuss what you think the effect will be on the spectral lines. Does frequency appear higher or lower? By how much? Recall:

Charles Hakes Fort Lewis College12 A source of light is approaching us at 3,000 km/s. All its waves are: A) Red shifted by 1% B) Blue shifted by 1% C) Not affected, as c is constant in all reference frames. D) Red shifted out of the visible into the infrared E) Blue shifted out of the visible into the ultraviolet

Charles Hakes Fort Lewis College13 A source of light is approaching us at 3,000 km/s. All its waves are: A) Red shifted by 1% B) Blue shifted by 1% C) Not affected, as c is constant in all reference frames. D) Red shifted out of the visible into the infrared E) Blue shifted out of the visible into the ultraviolet

Charles Hakes Fort Lewis College14 Chapter 9 The Sun

Charles Hakes Fort Lewis College15 The temperature of the photosphere of the Sun is about: A) 4500 K B) 5800 K C) K D) 1 million K E) 15 million K

Charles Hakes Fort Lewis College16 The temperature of the photosphere of the Sun is about: A) 4500 K B) 5800 K C) K D) 1 million K E) 15 million K

Charles Hakes Fort Lewis College17 What is the meaning of the solar constant? A) The regularity of the 11 year sunspot cycle. B) The fact that features on the Sun appear to never change. C) The stability of the Sun’s luminosity during its existence. D) The amount of energy received at the Earth’s surface per unit area and unit time. E) The fact that the amount of hydrogen turning into Helium in the core is fixed.

Charles Hakes Fort Lewis College18 What is the meaning of the solar constant? A) The regularity of the 11 year sunspot cycle. B) The fact that features on the Sun appear to never change. C) The stability of the Sun’s luminosity during its existence. D) The amount of energy received at the Earth’s surface per unit area and unit time. E) The fact that the amount of hydrogen turning into Helium in the core is fixed.

Charles Hakes Fort Lewis College19 l news/science-at-nasa/2003/17jan_solcon/ news/science-at-nasa/2003/17jan_solcon/ l main/index.html main/index.html

Charles Hakes Fort Lewis College20 Chapter 9 Sunspots

Charles Hakes Fort Lewis College21 Figure 9.15 Sunspots

Charles Hakes Fort Lewis College22 Figure 9.16 Sunspots, Up Close Darker (cooler) places on the Sun. Typically about the size of Earth (~10,000 km) Umbra - dark center (~4500K) Penumbra - lighter surrounding region (~5500 K)

Charles Hakes Fort Lewis College23 Sunspot Magnetism Zeeman effect - a slitting of spectral lines from magnetic fields. If you can measure the “splitting”, then you can determine the magnetic field. Magnetic field in sunspots Typically ~1000x greater than that in the surrounding region. Field lines typically perpendicular to surface (either N or S) Magnetic field disrupts the convective flow. (Hot stuff in the interior can’t “percolate” to the surface.)

Charles Hakes Fort Lewis College24 Sunspot Magnetism Sunspots typically occur in pairs A N-S pair will follow each other in the direction of the suns rotation. Ordering (N-S or S-N) will be opposite in northern and southern hemispheres. Direction reverses every 11 years.

Charles Hakes Fort Lewis College25 Figure 9.17 Sunspot Magnetism

Charles Hakes Fort Lewis College26 Solar Rotation The sun rotates differentially Equator – 25.1 days 60° latitude days Poles - 36 days Interior days

Charles Hakes Fort Lewis College27 Figure 9.18 Solar Rotation

Charles Hakes Fort Lewis College28 Solar Rotation Rope demonstration Every 11 years, the polarity of the magnetic fields reverse. Number of sunspots follows this 11 year cycle. Most recent maximum was in Solar Cycle - Two complete reversals of the magnetic field. Two sunspot cycles, or 22 years.

Charles Hakes Fort Lewis College29 Figure 9.19 Sunspot Cycle

Charles Hakes Fort Lewis College30 Figure 9.20 Maunder Minimum

Charles Hakes Fort Lewis College31 Active Regions Sites of explosive events on the photosphere. Most associated with sunspots (magnetic fields) Prominences - loops or sheets of glowing gas ejected from an active region. Flares - more violent; may cause pressure waves Coronal Mass Ejection - “bubbles” of ionized gas that separate and escape from the corona. If these hit Earth, they disrupt Earth’s magnetic field.

Charles Hakes Fort Lewis College32 Figure 9.21 Solar Prominences - ionized gas follows field lines

Charles Hakes Fort Lewis College33 Figure 9.22 Solar Flare - more violent; may cause pressure waves

Charles Hakes Fort Lewis College34 Figure 9.23 Coronal Mass Ejection - view from SOHO (Solar and Heliospheric Observatory.)

Charles Hakes Fort Lewis College35 As the Sun rotates, an individual sunspot can be tracked across its face. From Eastern to Western limb, this takes about: A) 12 hours B) A week C) Two weeks D) A month E) 5.5 years

Charles Hakes Fort Lewis College36 As the Sun rotates, an individual sunspot can be tracked across its face. From Eastern to Western limb, this takes about: A) 12 hours B) A week C) Two weeks D) A month E) 5.5 years

Charles Hakes Fort Lewis College37 Solar Interior/ Nuclear Fusion

Charles Hakes Fort Lewis College38 What about the internal structure?

Charles Hakes Fort Lewis College39 Solar Composition Element Number Percent Mass Percent H He O C N

Charles Hakes Fort Lewis College40 Figure 9.2 Solar Structure

Charles Hakes Fort Lewis College41 What about the internal structure? Core - temperatures hot enough for nuclear reactions Radiation Zone - Temperatures cooler, so no nuclear reactions. Hot enough so everything is ionized. Atoms can’t absorb photons. Convection Zone - Temperature cooler. Atoms form and can absorb radiation.

Charles Hakes Fort Lewis College42 Figure 9.6 Solar Interior

Charles Hakes Fort Lewis College43 How do we know what is inside the Sun?

Charles Hakes Fort Lewis College44 How do we know what is inside the Sun? l Standard model

Charles Hakes Fort Lewis College45 Figure 9.4 Stellar Balance

Charles Hakes Fort Lewis College46 Figure 9.5 Solar Oscillations

Charles Hakes Fort Lewis College47 Figure 9.7 Solar Convection

Charles Hakes Fort Lewis College48 Figure 9.8 Solar Granulation

Charles Hakes Fort Lewis College49 Figure 9.11 Solar Spicules

Charles Hakes Fort Lewis College50 Typically, a granule in the photosphere of the sun is about the size of? A) A city, ~20-30 kilometers across. B) Texas, ~1000 km across. C) The Earth, ~12,000 km across. D) Jupiter, ~100,000 km across.

Charles Hakes Fort Lewis College51 Typically, a granule in the photosphere of the sun is about the size of? A) A city, ~20-30 kilometers across. B) Texas, ~1000 km across. C) The Earth, ~12,000 km across. D) Jupiter, ~100,000 km across.

Charles Hakes Fort Lewis College52 From inside out, which is the correct order? A) core, convective zone, radiative zone B) photosphere, radiative zone, corona C) radiative zone, convective zone, chromosphere D) core, chromosphere, photosphere E) convective zone, radiative zone, granulation

Charles Hakes Fort Lewis College53 From inside out, which is the correct order? A) core, convective zone, radiative zone B) photosphere, radiative zone, corona C) radiative zone, convective zone, chromosphere D) core, chromosphere, photosphere E) convective zone, radiative zone, granulation

Charles Hakes Fort Lewis College54 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?