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Astronomy Exam 2
| Question | Answer |
|---|---|
| Spectral Types - Hot to cool | O, B, A, F, G, K, M |
| Star Composition | 75% hydrogen, 25% helium |
| Doppler Effect | Wavelength is shorter if source is moving toward us(blueshift), longer if sources is moving away(redshift). |
| Binary Star Systems | one star orbiting (b) another (a). By measuring the velocity of b, the orbiting star, we can determine the mass of star A. Need to measure distance from one star to another and time for one orbit |
| after hydrogen in core is exhausted | gravity contracts core, layer outside core fuses hydrogen, this expands outer shell into red giant, core continues to contract, stars fusing into carbon |
| death of low mass star | star expands more due to helium fusing in a shell around carbon core, star ejects its outer layers which form planetary nebula, and core becomes white dwarf(no energy, just slowly cool). Can steal hydrogen from neighbors causing nova |
| life cycle of low mass stars | interstellar cloud, main sequence star, red giant, planetary nebula, white dwarf. If it pulls material off companion star, it will be come nova, or supernova and explode if it takes too much |
| life cycle of high mass stars | continues fusing higher and higher dense elements. interstellar cloud, big main sequence star, red giant, massive supernova, crab nebula, neutron star if mass is low, black hole if mass is high |
| low mass stars | mass below 8M, live long steady lives |
| high-mass stars | masses above 8M live short and dramatic lives because gravity pushes down on it harder because of high mass, so fusion increases so it runs out of hydrogen quicker. Most massive are 100M |
| neutron star | Mass must be <3M after supernova. left by a massive-star supernova. similar to giant atomic nuclei, steady radiation emitted from poles while rotating(pulsar) |
| black hole | Mass must be >3M after supernova. has event horizon - point of no return, and singularity in middle. gravitational waves or ripples in space time are way to detect black holes |
| apparent magnitude | MEASURE of apparent brightness: smaller when star is brighter which happens when star is closer. larger apparent magnitude means dimmer apparent brightness |
| general relativity | Matter tells spacetime how to curve. Spacetime tells matter and light how to move. |
| when does fusion stop | when the core is iron because iron doesn't yield energy with fusion or fission. Core collapses, causing explosion due to energetic neutrinos |
Created by:
mttfrog13
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