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14 Cards in this Set
- Front
- Back
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open clusters
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not gravitationally bound
disk of galaxy young 1000 or fewer stars |
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globulars clusters
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millions stars
galactic halo very old gravitationally bound |
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dark nebulae
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dust blocks out light
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nova explosion
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occurs on surface of white drawf star. high temperature gas that reminas thick because the white drawf star does not react to temp increases by expanding.
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evidence for interstellar medium
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emission nebulae proves that there must be hydrogen gas.
narrow absorption lines show that there must be a cold gas in the way. the 21cm rules indicates a cold gas- these waves couldn't occur with a warmer gas. |
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luminosity and brightness
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luminosity is absolute whereas brightness depends on prospective.
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5 ways to detect binary systems
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Visual binaries-observation
Astrometric binaries- gravitational tug Spectroscopic binaries- red/blue shift in spectrum Eclipsing binaries - dips in light curve. |
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life of a solar like star
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1) proto star - a collapsed gas cloud
2- main sequence star - core collapsed enough for nuclear reactions - will stay here for 10 billion years with little or no changes. 3) red gaint phase - after star burns fuel it contracts then burns helium and puffs into a red giant. 4) planetary nebula - the outer layers of the red giant escape 5) white dwarf - the leftover core. 6) black dwarf - a completely cooled off white dwarf. |
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quasar
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highly luminous galaxy usually lumped together with a class of objects called collective galaxies. thousands to millions of times more luminous than regular galaxies.
hydrogen gas falling into a black hole causing tremendous amounts of energy to be radiated away. |
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types of galaxies
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elliptical- largest, many trillion stars.
little active star formation - little gas and dust - lots of evolved stars so they look red. Spiral - less stars more star formation. very blue light. lots og gas and dust. irregular - few million stars (fest stars . some active star formation. |
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super nova process differs from regular stars in .....
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no planetary nebula stage - instead when fuel is burnt out they explode instead of going on to become RED giants.
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using HR diagram to find distance
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provides a measure of apparent magnitiude which can be converted into brightness. - with many stars we can match each star to expected luminosity - with luminosity and brightness we can plug these 2 into a formula to find distance.
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distance determination methods
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parallax - we know!
cluster method - hr diagram estimating absolute magnitiude (luminosity) from spectral type and color the formula for distance. cepheids- period/luminosity relationship between period of variability and its luminosity. hubble- get velocity from shift in spectrum and use hubble law to get distance. |
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nebulae types
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dark - blocks out light
supernova remnant - shell of gas moving fast , this is where most heavy elements were created. planetary nebula-giant star slowly looses outer layers. reflection - dust surrounding hot blue star reflects light from the star. |
