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14 Cards in this Set

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open clusters
not gravitationally bound
disk of galaxy
young
1000 or fewer stars
globulars clusters
millions stars
galactic halo
very old
gravitationally bound
dark nebulae
dust blocks out light
nova explosion
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.
evidence for interstellar medium
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.
luminosity and brightness
luminosity is absolute whereas brightness depends on prospective.
5 ways to detect binary systems
Visual binaries-observation
Astrometric binaries- gravitational tug
Spectroscopic binaries- red/blue shift in spectrum
Eclipsing binaries - dips in light curve.
life of a solar like star
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.
quasar
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.
types of galaxies
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.
super nova process differs from regular stars in .....
no planetary nebula stage - instead when fuel is burnt out they explode instead of going on to become RED giants.
using HR diagram to find distance
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.
distance determination methods
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.
nebulae types
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.