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56 Cards in this Set
- Front
- Back
Main sequence life starts where?
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The ZAMS line
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Characteristics of Main sequence stars
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Hydrostatic Equilibrium
Hydrogen Fusion |
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Hydrogen Core Fusion-2 kinds
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P-P-temp<10MK
CNO-temp>15MK |
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Main Sequence Lifetime depends on...
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amount of fuel (mass)/rate of fuel consumption (luminosity)
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Lifetime at the top of the main sequence is ______ than life at the bottom
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shorter
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Which is more abundant, upper or lower MS stars?
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Lower
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If a star has a high mass, it's death will be...
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Complex
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Death of a low mass star
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H fusion ends because all H has been converted to He. Star contracts and shrinks to a white dwarf
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Death of a medium mass star
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H fusion ends because all H has been converted to He. As the star contracts, the internal temp rises to 100MK and the He is converted into Carbon. It then becomes a giant. When fusion ends, it becomes either a white dwarf or neutron star. It's ejected layer becomes a planetary nebula
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Mass of a white dwarf vs. a neutron star
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>1.4solar masses vs. <1.4solar masses
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Death of a high mass star
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H fusion ends and eventually the core turns to iron. Star collapses and material bounces off the core and the star tears apart to become a supernova. The remaining core collapses to form a neutron star or black hole
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Neutron Star vs. Black Hole
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<2.5-3 solar masses vs >2.5-3 solar masses
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Pulsar
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a neutron star's beam of radiation
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Chandrasekhar Limit
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White dwarf<1.4 solar masses
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Put in order of diameter size, smallest to largest: white dwarf, neuton star, black hole
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NS, WD, BH
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Degeneracy of a white dwarf
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Electron Degeneracy Pressure
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Degeneracy of a neutron star
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neutron degeneracy pressure
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Singularity, Event Horizon, and Schwarschild radius for black holes
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0 diameter, the place where events can be seen before entering the black hole. Rsch is proportional to the mass of the black hole
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Naked Eye View of the Milky Way
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hazy band of light around the celestial sphere
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Galileo
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discovered that the milky way is made up of thousands of stars
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Herschels
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concluded that the sun is near the center of the milky way by counting stars in bright regions
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Shapley
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finds that the sun is not at the center of the milky way
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Leavitt
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studied cepheid variables (pulsars) in the two magellanic clouds and discovered a period-luminosity relationship
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Shapley 2
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Studies RR lyrae variables in globular clusters and finds the distance to the clusters and that they are centered around a point 50,000 ly away
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Globular Cluster
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100,000-2 million stars in a ball located in and around sagittarius
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Trumpler
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Finds that dust dims starlight and that the center of the milky way is only 26,000 ly away
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Structure of the Milky Way galaxy
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Central bulge with a disk and halo
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Open Cluster
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10's-1000's of stars with little symmetry located along the milky way
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Sun's orbit around central bulge
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takes 225 million years
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Method to find the mass of the milky way
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mass of star=a au cubed/p years squared
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Mass of the Milky Way
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One trillion solar masses
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What percentage of the Milky way is dark matter?
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90%
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What is dark matter?
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Matter indicated by gravity but not seen at any wavelength
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Method to find the age of the milky way
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Look at the stars turnoff point on an HR diagram
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If a star has a lower turn off point it is...?
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Older
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Age of the Milky Way
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13 billion years
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Nucleus of the Milky way
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Sag A at radio
Sag A* at x-ray Orbit of S2 around A* at infared |
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Mass of black hole at center?
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2.6 million solar masses
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Messier Catalog
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Messier listed fuzzy, non moving objects M1-M110
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New General Catalog
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Dreyer listed 1000's of fuzzy objects
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The Great Debate
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Shapley vs. Curtis
Spiral Neb part of MW vs. Spiral Neb other galaxies |
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Hubble and Humason
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Observed cepheid variables in M31, it was too far away to be part of the milky way
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Baade
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Discovers two types of cepheid variables
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Total number of galaxies
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100 billion
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Local Group
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40 galaxies within 5 million ly of the MW
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Galaxy Cluster
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group of galaxies
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Supercluster
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group of galaxy clusters
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3D map of galaxies
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bubbles surrounded by sheets of galaxies
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Slipher
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finds that all spiral nebulae have a red shift in spectral lines
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Hubble
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Recessional speed is proportional to distance (further away=greater speed away)
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Hubble's Law
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Recessional Speed=Hubble Constant * distance
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Einstein
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therory of relativity; spacetime is curved by matter
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Friedman
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finds that universe is either expanding or contracting
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Open Universe
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keeps expanding with a rate >0 as time goes to infinity
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Closed Universe
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expansion stops due to gravity, then contracts
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Flat Universe
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expansion is forever, buy expansion=0 as time reaches infinity
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