Summary Chapter 7-8 - Astro 10

Summary Chapter 7-8 - Astro 10 - Chapter Summaries Chapter...

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Unformatted text preview: Chapter Summaries Chapter 7: Atoms and Starlight 1. Properties of Matter Atom Atom = Nucleus (protons + neutrons) + electron cloud Protons have + charge Electron cloud has charge Neutron has no charge (neutral) Elements are defined by their Atomic Number (# protons). Atomic Mass Number (# protons + # neutrons) Isotope (change in # neutrons) Ion (change in electron either gain or loss of electrons) Ionization; plasma Molecules Energy is stored in atoms: Bohr atom, Ground state, excited electron states; Energy level transitions, Balmer lines 2. (Review from Chapter 6) Properties of Light Light can be a wave (wavelength, frequency) wavelength * frequency=speed of light = constant Light can behave like particles Photons Energy = constant*Frequency E ~ f ~1/wavelength Electromagnetic Spectrum 3. Color related to Energy; color and temperature Temperature; temperature scales: Celsius, Fahrenheit, Kelvin Thermal energy Black Body radiation Properties of thermal radiation (Wien's Laws) 1. Hotter objects emit more light at all energies 2. Hotter objects emit a greater fraction at higher energies 4. Learning from Light Continuous spectra What is it? What causes it? Emission line spectra What is it? What causes it? Absorption line spectra What is it? What causes it? Chemical "Fingerprints" Molecular bands Thermal radiation 5. The Doppler Shift radial velocity, transverse velocity Red shift, Blue shift Rotation, Line broadening Chapter Summaries Chapter 8: Sun 1. General Sun Facts & Information Sun is ionized gas (charged particles) Sun's core temp is 15 Million K and surface temp is 5800 K Sun is made of : Hydrogen (90%), Helium (9%), metals(1%) Sun is 1 AU from Earth 2. Solar Structure core radiative zone convective zone photosphere chromosphere (transition zone) corona solar wind Solar Feature coronal holes flares spicules prominences 3. Helioseismology (solar vibrations) only way to investigate the Sun's interior 4. Sun's energy comes from nuclear power, not coal, not wood, not gravitational potential from contraction (Kelvin Helmholtz), not impacts from comets and/or meteorites 5. Four Fundamental Forces of Nature: 2 Gravity (depends on M/r , infinitely long range force) Electromagnetism (long range force, carried by photons) Weak Nuclear Force (very short range : radius of atom) Strong Nuclear Force (extremely short range: radius of nucleus) 6. Difference between nuclear fusion and nuclear fission 7. Nuclear Fusion Start: 4 protons Finish: 4He nucleus + 2 gamma rays + 2 positrons + 2 neutrinos + LOTS OF ENERGY neutrinos can travel thru stuff; leaves Sun quickly; travels like a photon positrons electron anti-matter; hangs out in the Sun gamma rays eventually "turns" into visible photons Chapter Summaries 8. Energy production in the Sun/stars: Fusion occurs up to Iron (Fe) { light neuclei fuse into heavier nuclei H He; C N,O, ... until Iron) Fission happens with Iron (Fe) and higher elements 9. Transport of Energy through the Sun radiative diffusion (photons bounce randomly among the gas particles ) convection Granulation is evidence of the convective layer 10. Solar Neutrino Problem (resolved when discovered there are 3 kinds of neutrinos) 11. Solar Activity (due to magnetic field) Convection produces granulation on the photosphere Magnetic field causes: Sunspots , Sunspot Cycle (11 years, magnetic field flip/flop=22 years) (The Maunder Minimum (Little Ice Age") 1650 1700 ) Solar Flares Solar Prominences Space Weather: Solar Aurora, Coronal Mass Ejections (CME) Magnetic field is most likely due to Sun's differential rotation (equator rotates at a different rate faster- than the poles) Zeeman Effect : spectral line splits into two lines due to the magnetic field 12. Limb darkening is evidence of Sun's atmosphere ...
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