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PHYS 206 Detailed Outline


Last modified 18 Feb 06

Textbooks:


Topic 1. What is in the Universe and how big are they ?

Videotape: Powers of Ten

 "Astronomical" numbers  Scale of the Earth, and of the Earth-Moon system  Scale of the Solar System  Distances to the stars: Light-years  The Milky Way: Our galaxy  Other galaxies  Clusters of galaxies.


PART I : THE STARS


Topic 2. The Sun: An ordinary star

2.1. Overview
 Size and distance  300 000 Earth-masses  Hot sphere of gas  Rotation
2.2. Outer layers of the Sun
 Photosphere  Spectrum  Chemical composition  Chromosphere  Corona  The Solar Wind
2.3. Solar Activity
 Granulation  Sunspots, magnetic fields and their cycles  Prominences and flares  Long-term variability?

Topic 3. Solar energy: Source of life on Earth

3.1. Where does the Sun's energy come from?
 Solar constant  Coal?  Gravitational energy?  Nuclear reactions   E=mc2
3.2. Solar Interior
 Gas/Plasma  Hydrostatic and thermal equilibria  15-million-degree core  Random-walk of photons  Convection  Solar pulsations  Solar neutrino problem

Topic 4. Looking at stars

4.1. Rungs 1 & 2 of the Cosmic Distance Ladder
 Parallax-good to 100 ly  Parsecs  The nearest stars
4.2. Luminosity & Apparent Brightness
 An inverse square law
4.3. Rung 3 of the Cosmic Distance Ladder: Motional calculations
 Secular parallax  Moving clusters (Hyades)  A few hundred ly
4.4. Colors and spectra
 Color: Temperature  Absorption lines: Composition  Doppler shift: Radial velocity  Broadening: Rotation  Splitting: Magnetic field
4.5. Other bands
 Infrared, radio, x-ray, etc...

Topic 5. Double stars

5.1. Binary stars
 Eye-test of the middle ages  Visual binaries  Spectroscopic binaries  The demon star: an eclipsing binary  Mass exchange in binaries
5.2. Two-body problem gives mass
 Weighing the Earth  Mass of the Sun  Stellar masses from binaries  Range of stellar masses
5.3. Mass-luminosity relation
 The more mass, the more luminosity
5.4. Diameters of stars
 From eclipsing binaries  From radiation laws

Topic 6. Stellar classes: The giants, the dwarfs, the average ones...

6.1. The nearest and brightest stars
 The Centauri System  Sirius  More dim stars than bright
6.2. The Hertzsprung-Russel Diagram
 Main Sequence  Giants, supergiants, white dwarfs
6.3. Rung 4 of the Cosmic Distance Ladder: Main sequence fitting
 Open Clusters
6.4. The stellar recordholders
 Most luminous and most massive: Blue supergiants  Largest and least dense: Red supergiants  Least luminous and least massive: Red dwarfs  Densest: White dwarfs ???

Topic 7. A star is born

7.1. Formation of stars
 Molecular clouds  Collapse: Protostar  Failures: Brown dwarfs  Chain reactions  Observations
7.2. Digression: Why can't I see the at night the beautiful colors of astronomy posters ?
 Cones and rods in the retina  Night blindness  Color blindness
7.3. Formation of, and search for planetary systems
 Disks around protostars  Infrared search  Doppler search  Found !!!

Topic 8. We are children of the stars

8.1. Big stars live fast and die young...
 Destiny written at birth: The Russel-Vogt Theorem  Bigger stars exhaust their core hydrogen faster
8.2. Red giants
 Recall: Pressure vs. gravity  Helium core - shell hydrogen burning -> expansion: Sun will eat up Mercury and Venus!  Helium burning  All heavier elements cooked inside massive giants!  Mass loss

Topic 9. Stardeath I and starcorpses I: White dwarfs and novae

9.1. White dwarfs
 Degeneracy pressure  Solar-mass, Earth-sized...
9.2. Novae
 "Guest stars"  Red giant/white dwarf binaries  Ignition of accumulating shell  May repeat

Topic 10. Stardeath II: Supernovae: Brighter than hundred billion Suns

 The Chandrasekhar Limit  Iron core, collapse and bounce  Violent death of a big star: Type II supernova  Elements heavier than iron  Scatterer of ashes  May outshine galaxies!  The Crab nebula  SN 1987 A  Type I supernovae

Topic 11. Starcorpses II: Neutron stars and Pulsars

11.1. Neutron stars
 Early prediction  Core collapse in Type II supernovae  The neutrino flash
11.2. Pulsars
 "Miss Bell's "Little green men"  The Crab pulsar  Rotating neutron stars

Videotape: Death of a star

Topic 12. Starcorpses III: Black holes

12.1. Final state of very massive stars
 If neutron degeneracy pressure is not enough, nothing is...
12.2. Black holes
 Not even light can escape  Event horizon  Curved spacetime  Gravitational lens  Singularity  Mini black holes  Hawking Radiation  Supermassive black holes  Discovery of black holes


PART II: GALAXIES AND THE UNIVERSE



Topic 13. The Milky Way

13.1. The idea of "galaxy"
 The phenonemon of "Milky Way"  Herschell's "star gauging"
13.2. Size of the Galaxy
 Variable stars: Cepheids and RR Lyrae  Period-luminosity relation  Shapley and Globular clusters in Milky Way  Classical Cepheids as Rung 5 of the cosmic distance ladder  RR Lyrae as Rung 6  Rung 7: Type II Cepheids
13.3. Structure of the galaxy
 Disk with dust  Central bulge  Halo  Rotation and spiral arms  Fast-old and slow-young!  Dark matter  Supermassive black hole at center?

Topic 14. Galaxies and the expanding universe

14.1. Other galaxies far, far away
 "Island Universes" ?  The Shapley-Curtis Debate  Hubble's resolution: Cepheids in Andromeda  Spirals-ellipticals-irregulars
14.2 The Rest of the Cosmic Distance Ladder
 The concepts of standard candles and standard rulers  Brightest stars (sc), Globular Clusters (sc), HII regions (sr)  Tully-Fisher relation (sc), supernovae, etc...
14.3 Expansion of the Universe
 Redshifts  The Hubble Law
14.4 Quasars and Active Galactic Nuclei
 Big redshifts mean extreme luminosity  ...or do they?  Active galaxies  Where does the energy come from? Supermassive black holes ?
14.5 Large scale structure of the universe
 Hubble Survey  The Local Group  Clusters of Galaxies  Superclusters  Voids, sheets, filaments, The Great Wall: Cheese or sponge?
14.6 The Formation and Evolution of Galaxies
 Galactic ages (!)  Which scale formed first?

Topic 15. The Big Bang: The past and the future of the universe

15.1. A brief history of cosmology
 Ancient cosmologies: Geocentrism and the celestial sphere. "Planets" and days of the week.  Galileo's telescope, Copernicus, Newton. End of geocentrism.  Olbers' paradox.  Galactic dimensions (1917).  The Cosmological Principle.  Einstein's biggest "blunder": The static model.  Friedmann-Lemaitre model (1922-27).  Debate on nature of spiral nebulae.  Resolution by Hubble (1924).  First estimate of age of Earth.  Discovery of expansion of the universe (1929).  The age problem.  Gamow ('46) and "Big Bang".  The "perfect cosmological principle" and steady-state model.  Prediction of cosmic background radiation (CBR).  Corrections to distance scale, resolution of the age problem.  Discovery of CBR.  Uncertainity in Hubble constant.  Possibility of a new age problem  Acceleration of expansion?
15.2 The past of the universe
 Expansion means a beginning  Hot in the beginning, cools as it expands.  First, radiation dominated Temperature of the primordial soup  Quark-gluon plasma  Formation of neutrons, protons, etc. (Hadronization).  Annihiliation of hadrons, small excess of matter over antimatter.  Neutrino decoupling  Annihiliation of electrons and positrons.  Helium synthesis.  Matter domination.  Formation of hydrogen atoms (Recombination)  Transparent universe --> CBR.
15.3 The future of the universe and the dark matter problem
 Open and closed universes  Critical density.  Not enough luminous matter.  Dynamical measurement of mass at different scales, evidence for dark matter.  Most of the universe may be exotic matter.  Expansion forever?
15.4 Sucsesses and problems of the standard Big Bang
SUCSESSES:  CBR  Primordial light element abundances. PROBLEMS: The horizon problem: Horizon smaller at recombination time.  The flatness problem: critical density is unstable, fine tuning required. SSB in early universe --> The monopole problem
15.5 Solution of Problems: The Inflationary Universe
 "False vacuum". p = -(density) --> density = const. --> Exponential growth by ~50 orders of magnitude.  Observable universe a very small part of the domain.  Horizon, flatness, monopole problems solved
15.6 Open questions
 Dark matter: What is it? Black holes? Dead stars? Jupiters?  Nucleosynthesis limit on baryons.  Massive neutrinos? WIMP's? axions? cosmic strings?  Why matter-antimatter asymmetry?  How did large-scale structure form?  Initial fluctuations required: COBE results.  Dark matter important.  Flat and accelerating universe?  The anthropic principle.


PART III: GOING INTO SPACE



Topic 16. The Past: From Sputnik to the Space Shuttle

16.1. Firecrakers to Saturn-V: Rocket Technology
 Chinese firecrackers and medieval weapons  Goddard  V-2 and von Braun
16.2 The "Sputnik Crisis" and the Kennedy pledge
 First satellite: Sputnik  "Sputnik Crisis" and the Mercury Program  Vostok 1 and the first human in space: Gagarin  The Kennedy pledge
16.3 The race for the Moon
 First woman in space: Tereshkova  Voskhod 2: First "spacewalk" by Leonov  The Gemini Program  Apollo 8: First around the Moon  Apollo 11: A giant leap  Apollo 17: The End  Disasters: Nedelin, Apollo 1, Soyuz 11
16.4 Lone explorers: Planetary probes
 Pioneers, Veneras, Vikings, Voyagers...  Galileo  Cassini ?
16.5 The Shuttle Program and the Challenger Disaster
 Launch like a rocket, land like a plane  Cargo bay and manipulator arm  Challenger Disaster: 3-year freeze  HST and its repair

Topic 17. The Present and Near Future: Commercialization of Space

17.1. The really fixed stars: Communication satellites
 Geosynchronous orbit  Türksat
17.2 GPS, EOS, SDI, 007
 Where am I?  Earth Observing System  "Star Wars"  Spy in the sky
17.3 Orbital observatories and factories
 Get above the atmosphere: Hubble Space Telescope, COBE, IRAS, GRO, etc...  Microgravity: less stress, new chemistry

Topic 18. The Far Future: Living in Space

18.1. Colonies in space, not on planets
 "Planetary chauvenism"  Gravitational wells of planets  Other constraints: surface gravity, atmosphere, length of day...  Surface-volume ratio
18.2 Constructing islands in space
 Skylab, Mir and Freedom: Pioneers  Material: asteroids  Cylindrical geometry for gravity  Mirrors provide sunlight  Controlled climate
18.3 Life in space colonies
 Social diversity  "Geographical" diversity  Independence  Utopias?

Topic 19. Space Travel

19.1. The rocket principle
 Action=reaction  Propellant  Fuel
19.2 Variations on a theme
 The first nuclear idea: The Orion Project  Deadalus Project  The nuclear salt water rocket  The ion rocket  The photon rocket  The ramscoop (Bussard) engine  Annihiliation engine
19.3 Alternatives
 Solar sailing  Laser-driven spaceship
19.4 Other considerations
 Acceleration constraints Spin the ship!  The any-acceleration ship  Cosmic speed limit  Problems at relativistic speeds  Space arks  Hibernation  Aerobraking  Gravity assist
19.5 Planet-to-orbit commuting: The Space Elevator
 Rockets are wasteful  polluting  noisy  irreversible  expensive  The solution
19.6 Impossibilities (?) and FTL
 Star Trek's warp drive  Asimov's `jumps'  Blish's spindizzy  Niven's hyperdrive

Topic 20. SETI: Are other intelligent beings out there?

20.1. Life
 Is a definition possible?  Philosophical and religious implications of ET life
20.2. Life in the Solar System?
 Life on Earth  Mars?  Europa?  Titan?  Elsewhere?
20.3 Other planetary systems?
 Does life need a planet?  There seem to be extrasolar planets  Trojan points of binary stars?
20.4 Intelligent life in the galaxy?
 The Drake equation  The Kardashev classification  Dyson spheres  The Galactic Zoo hypotesis
20.5 Pro
 Possibility of planetary systems  Ancient life on Mars  Miller-Urey experiment  UFO's ?
20.6 Con
 Improbability of similar-level civilizations  von Neumann machines and galactic colonization  "Where are they?"  Should intelligence be observable?
20.7 Search
 UFO's? (probably) no.  Search for a radio message  Other evidence?  So far, no sucsess


If you have any comments or questions or corrections, contact me at

semizibr@boun.edu.tr

-Ibrahim Semiz