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6 Cards in this Set
- Front
- Back
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5 properties of a central engine of an active galaxy
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1. They have high luminosities generally greater than the 10`37 W characteristic of a bright normal galaxy
2. Their energy emission is mostly nonstellar- it cannot be explained as the combined radiation of even trillions of stars 3. their energy output can be highly variable, implying that it is emitted from a small central nucleus much less than a parsec across 4. They often exhibit jets and other signs of explosive activity 5. their optical spectra may show broad emission lines, indicating rapid internal motion within the energy-producing region 6. often the activity appears to be associated with interactions between galaxies |
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Explain the 2 futures of our existing galaxy
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The Big Crunch: Universe will re-collapse under its own mass; possible cycles of Big Bang explosions
The Cold Death: Universe will expand forever slowing down time and losing kinetic energy |
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Know the 7 stages in cosmic history of life
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1. particulate
2. galactic 3. stellar 4. planetary 5.chemical 6. biological 7. cultural |
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Explain what the earth probably looked like in earth history, pre-life
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chemical evolution
-washed out by volcanism, meteors and erosion |
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Explain what Drake’s equation means, and how do we interpret the results
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number of technological intelligent civilizations = rate of star formation, average over the lifetime of the galaxy X fraction of stars having planetary systems X average number of habitable planets within those planetary systems X fraction of those life-bearing planets on which intelligence evolves X fraction of those intelligent-life planets that develop technological society
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Explain how a Quasar can give off so much energy
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What we do know about them is that they emit enormous amounts of energy. They can burn with the energy of a trillion suns. Some quasars are believed to be producing 10 to 100 times more energy than our entire galaxy. All of this energy seems to be produced in an area not much bigger than our solar system.
possibility that quasars are produced by super massive black holes consuming matter in an acceleration disk. As the matter spins faster and faster, it heats up. The friction between all of the particles would give off enormous amounts of light other forms of radiation such as x-rays represent a very early stage in the formation of galaxies. The energy we see may be ejected from the cores of these very young and very active galaxies. Some scientists even believe that quasars are distant points in space where new matter may be entering our universe. This would make them the opposite of black holes. |
