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127 Cards in this Set
- Front
- Back
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The Orion Nebula is
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A large interstellar gas and dust cloud containing many young stars
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How does the average density compare to Jupiter?
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The sun has approx the same density
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The H-R diagram is a stat plot of which of the following stellar perimeters?
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Luminosity and surface tempature
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An astronomer observes the split in spectral lines, this means..
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They contain strong magnetic fields
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The relationship between mass and luminosity of stars on the main sequence is that...
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the greater the stellar mass the greater the luminosity
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Hydrostatic equilibrium in the sun means
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The balance of gravity inwards and the gas pressure outwards
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When is electron degradation in a star important?
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Just before the start of helium burning in the core
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The spectral type of a star is most directly related to
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Surface temp
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What occurrence defines the end of a protostar phase of a stars life and the start of the main sequence phase?
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nuclear reactions in its core
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ON the H-R diagram which direction does the position move after hydrogen burning end?
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Upper right
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Sunspots are caused by
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Differential rotation and its effect on weak magnetic fields
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A white dwarf is supported from collapse under gravity by
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Degenerate electron pressure in the compact interior
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At what distance is absolute magnitude calculated?
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10 pcs
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The star Arcturus is a K2-3 star which means
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Cool Giant
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2 most abundant resources in the universe are
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Helium and hydrogen
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Semi detached Binary system
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One star fills the Roche lobe while the other doesn't
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Temp for helium into carbon
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100 Million kelvin
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Characteristic color of emission nebula is
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Red
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Process that provides the power of the sun
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Fusion of hydrogen into helium
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Transfer of one stars mass to another
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Semi detached binary's
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Coronal holes shows up in photos taken at what wavelength
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X-Ray
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All stars on the main sequence
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Generate energy by helium into hydrogen fusion in their cores
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The effect of interstellar dust on starlight
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Dim and Redden by scattering blue light
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The helium flash results from
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Electron degradation of quantum crowding of low mass red giant
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What is the temperature of the suns Corona
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1-2 Million K
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A white dwarf is
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A low mass star at the end of his life
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Last nuclear burning stage for low mass star like the sun
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Fusion of Helium to form Carbon/oxygen
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Center outward order of layers of the sun
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Radiactive zone, Convection zone, photosphere, Chromosphere, Corona
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Protostars are star that are
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Slowly contracting and heating up
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Total time the sun will stay on the main sequence?
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10 Billion years
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Apparent magnitude
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Brightness of a star as seen from earth
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Proper motion of a star is defined as
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apparent motion across our sky against background stars
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study of stars in clusters has helped astronomers
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Stellar evolution/development of stars with time
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if the stellar parallax is .01 how many parsecs
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100pcs
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Mass limit for the Chandrasekhar
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1.4
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How much longer can the sun generate energy?
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5 billion years
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The age of a cluster can be found by
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Its turn off point on the main sequence of the H-R diagram
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What is the most important factor that determines the point in the H-R diagram where a protostar reaches the main sequence?
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The mass of the protostar
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Granulation on the surface of the sun is caused by
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Convection currents heating from beneath
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Which of the spectral classes is the hottest?
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B, G, A, K
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Order form decreasing spectral class
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OBAFGKM
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The evolution of a star is controlled by its
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Initial mass
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A neutrino is
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Elusive subatomic particle having little to no mass and very hard to detect
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Bright stars at the center of the H2 region/ emission nebula are
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Young O-B stars
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Sunspots are
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Cooler and darker regions of the suns surface
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A brown dwarf is
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An object between a planet and a star with not enough mass to start nuclear reactions
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The temp of the suns Photosphere
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5800K
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What % of stars in the sky are on the Main sequence?
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90%
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what is a red giant?
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A star burning hydrogen into helium in the shell around its core
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Name of the suns visible surface?
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Photosphere
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A pulsar is most probably formed
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In the center of a supernova explosion
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what separates a blackhole from the rest of our galaxy
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its even horizon
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Maximum mass for a neutron star is
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3 Solar masses
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Young neutron rich stars are found
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in the disc and the spiral arms
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How far away is the sun from the center
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8pcs
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1790's William Hershal measured the suns position in our galaxy by
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Counting the density of stars in different directions
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What quantum transition occurs inside cool hydrogen to produce 21 cm radio proton
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An electron in the ground atomic state reverses its direction of spin with respects to that of the proton
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Component that keeps us from seeing the galactic center
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Interstellar dust
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The mechanism that gives a rise to NOVA
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Matter from a companion star falling into a white dwarf in close binary system causing a nuclear explosion
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Neutron stars are created by
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Type 2 supernovae
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Which type of stars are not found in the halo
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O type
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Mass limit for white dwarf
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1.4
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Method used by Harlow Shapley to estimate our suns location was a measurement of
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Locations of globular clusters
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What is a singularity?
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A point of infinite density
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Light coming from a neutron star becomes reddish
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Gravitational redshift
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Main difference between type1 and type2 supernova
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Hydrogen lines are prominent in the section of type 2 but absent in type 1
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The core collapse phase at the end of a massive star is triggered when
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Nuclear fusion has produced a significant amount of iron in its core
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Chinese astronomers recorded the phenomenon in 1054 ad
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A supernova visible in daylight
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What is the law of cosmic censorship?
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There are no naked singularities, every black hole must be surrounded by a event horizon
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Type 2 supernova is the
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Explosion of a massive star after silicon burning has produced a massive iron core
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The milky way is what type of galaxy
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spiral
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Xrays that come from the vicinity if a blackhole originate from
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Just outside the event horizon on the accretion disk
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what si photodisinigration
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Splitting apart of atomic nuclei from gamma rays
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what is the correct sequence of increasing mass
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white dwarf, neutron star, blackhole
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Cephied variables and rr lyrae stars are important because
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Distance measurement
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Interstellar matter blocks our view from the disk
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More at optical less at infrared and not at all at radio
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Blackholes are named because
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No light or any electromagnetic radiation can escape it
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what type of object has been proposed to explain the tremendous activity detected in the center of our galaxy?
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Supermassive blackhoel
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According to general relativity why does the earth orbit the sun?
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space around the sun is curved and the earth follows the curved space
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First pulsar was discovered by
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Joselyn bell 1967
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In what constellation does the center of our galaxy located
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Sagitaruis
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Type 1a supernova is
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the explosion of a white dwarf in a binary system after mass has been transferred to it from its companion
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How does the gravitational field effect the passage of time
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Clocks in the gravitational field move slower than outside
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THe Schwarzchild radius is the distance from the singularity to the
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Event horizon from which light cannot escape
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Synchotron radiation is emitted whenever
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CHarged particles are forced to move along curved pathes within a magnetic field
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Newtons law of gravity states why does the earth orbit the sun?
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the sun exerts a gravitational force on earth across empty space
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which components make up the disk of our galaxy
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young O and B stars, dust and gas
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Which galaxy type contain little no no intersteller dust
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elipticals
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What is the central engine of an active galaxy?
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Super massive black hole at the center of an accretion disk with jets of material coming out perpendicular tot he disk
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Hubble classification for a galaxy having a disk and central buldge with smooth light distribution but no spiral arms
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S0
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Very flat ellipical is a
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E7
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The local group is
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The cluster of galaxies that the milkyway is in
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HWat is the tempature of black body radiation that we detected that originating from the big bang?
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3k
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Energy output from a quazar is equal to
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1000 bright galaxies
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What is cosmic redshift?
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The stretching of wavelengths of photons as they travel though expanding space
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What do cosmologists study
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The origin structure and evolution of the UNIVERSE
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The hubble classification of a galaxy having loosly wound spiral arms originating at the ends of a bar through the central buldge
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SBC
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What is a super cluster of galaxies?
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Cluster of galaxy clusters
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Seyfert galaxies are
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Active galaxies with bright star like nuclei
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In hubble classification scheme for spirals galaxies, the tightness of the winding of the spirals arms appears to be directly related to
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The size of the central bulge
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Which galaxy type contain primarily type 2 long lived stars
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elliptical
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what does a spiral galaxy look like edge on
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a thick flat line with a bulge at the center
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A starburst galaxy appears to a galaxy in which
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A collision with another galaxy triggers a burst of star formation
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IN the 1970's it was discovered that among spiral galaxies the wider 21 cm radio emission line is the brighter the galaxy is
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Tally Fisher
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Which of the following is not charactoristic of ellipticals
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they have a disk and a central bulge but no spiral arms
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A quazar is now thought to be a
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center core of an active galaxy
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What is cosmic microwave background radiation?
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the radiation left over from the big bang
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Quazars appear to be
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very distant, intrinically bright objects moving away from us at very high speeds
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In relation to earth what does the term isotropic mean
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Expansion is the same in all directions
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WHat observational fact makes astronomers think that a quazar is very small
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The rapid variation of the intensity of its source
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Hubble distance velocity relationship
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the further away the object is the faster it is traveling
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what will happen if the universe is unbound?
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Expand forever
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What was the COBE satalite used for?
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Cosmic microwave background radiation
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Which 2 perimeters representing observations of distant objects are related in Hubbles law
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The distance of the object and the redshift of its light
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How are megellanic clouds classified
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Irregular
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A radio galaxyis any galaxy that
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has 2 lobes 1 on each side which emit synchrotron radiation at radio wavelength
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In which galaxy type is start formation no longer occurring
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E0 Elliptical
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If space is flat
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it will expand forever, reaching zero expansion speed after an infinite amount of time
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Who first showed the reccessional speeds of galaxies increase with increasing distance
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Hubble
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The hubble classification for a galaxy with a prominent central bulge is
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SA
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What perimeter if the present universe more than any other is considered to be critical in determining the ultimate fate of the universe
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Average density of matter
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The largest range in galaxy sizes are
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elliptical
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Synchrotron radiation is produced whenever
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Electrons move in spirals around in a magnetic field
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Variable stars such as cepheid variables and RR layrae stars are used in what important measure in astronomy
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Measurement of distances to galaxies
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Hubble relation links 2 characteristics of distant objects in the universe
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Distance and velocity of recession
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what is the meaning of cosmological principal?
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we do not occupy a general special place in space because the universe is the same on average
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what will happen if the universe is bounded?
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Big crunch, Fall back on itself
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