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51 Cards in this Set
- Front
- Back
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spiral density wave
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the theory that the massive black hole in our galaxy sends compression waves thru the galaxy and creates new spiral arms
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interstellar medium
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material between stars gas and dust
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21 cm radiation
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hydrogen spin flip –radio waves
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dark matter
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90 percent of matter in galaxy—
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cosmic rays
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particles shot out by supernova
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dust grains
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carbon and silicate dust between stars
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emission nebula
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heated glowing gasses
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reflection nebula
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bluish from dust reflection
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molecular clouds
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prime areas for formation
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spirals
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20% of all galaxies –lots of dust and gas—normal most abundant of spirals
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elliptical galaxies
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80% of all galaxies—most are dwarfs the super large ones eat others
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irregular galaxies
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near collisions or collisions made them—our satellite galaxies are the Magellan clouds and are irregular
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standard candle
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each type of galaxy has certain absolute magnitude
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clusters
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galaxies are not alone but in clusters
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super cluster
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clustering of clusters
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hubbles law
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the farther the faster
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hubbles constant
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50 to 100 km/sec/mpc
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cepheid
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1 to 100 days –yardsticks to other galaxies
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period luminosity
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how we use Cepheid’s to measure distance
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cosmological prinicple
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averaged over large enough distances, one part of the Universe looks approximately like any other part: homogeneous and isotropic
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cosmological red shift
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all bodies are moving away –further the faster
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cosmological horizon
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how far back can we see
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look back time
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time since the beginning of universe
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radio galaxies
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colliding galaxies—main reason
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quasar
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quasi stellar objects –small energetic cores of early galaxies
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dark matter
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makes up to 90 percent of universe
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dark energy
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makes up 60 percent of dark matter
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rotational curve
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stars do not slow down as they go around the galaxy because of dark matter
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orbit in clusters
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galaxies orbit each other faster because of dark matter
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gravitational lensing
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light is bent by galaxies more than it should because of dark matter
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MACHOS
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massive compact halo objects –may be dark matter
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baryonic matter
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normal matter about 10 percent of galaxy
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WIMPS
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weakly interacting particles –may be dark matter
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large scale structures
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clusters of galaxies and clusters of cluster called super clusters
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critical density
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matter needed to open or close the universe
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recollapsing universe
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high critical density so universe stops expansion and recollapses
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critical universe
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—flat universe—this is what we think it is—barely expanding
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coasting universe
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expands forever
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accelerating universe
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expansion goes faster
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matter
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that which dominates the baryonic materials in our universe
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antimatter
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opposite to our matter
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big bang
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universe expands out rapidly
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planck era
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quantum ideas
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GUT
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grand unification of all forces
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Inflation
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time at beginning that universe expanded quickly
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cosmic microwave background
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left over of early hot universe –3K now
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obler's paradox
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why is night sky dark—cannot have infinite size and infinite number of stars
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natural selection
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Darwin proposed
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mutation
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biology changes life
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habitable zone
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area around a star that life can exist
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drake equation
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probabilities of life that communicates in universe
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