AST 105: Test 2
42 Cards in this Set
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chandrasekhar limit
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1.4 x the mass of the Sun. an upper bound on the mass of a stable white dwarf star
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Dark Matter
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matter that we cannot see that acts as a "glue" holding the universe together. accounts for 90% of the mass of the galaxy.
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Red Dwarf
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low mass, less than 10% the mass of the sun. low surface temps. lives a long life around 500 billion years
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White dwarf
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When nuclear reactions stop, gravity is the stronger force. Extremely dense core that will glow until it cools.
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Brown Dwarf
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if a PMS star is small (less than 10% the mass of the sun) gravity isn't sufficient to contract the star so that the core temp can reach 10 million K. Juipter
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Edwin Hubble
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was first to determine that not all stars were part of the milky way. did so by observing cepheids in M31.
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Galaxies
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there are 100 billion galaxies in the viable universe
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Galaxy shapes
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Spiral: 1. flocculent 2. Grand Design 3. Barred Spiral
Elliptical: measured from E0-> E7
Lenticular: like a spiral with out the arms
Irregular: all over the place
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Giant stars
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M-S stars with masses greater than .4 x the mass of the sun become giants. When the hydrogen in the core is completely fused into Helium
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super giant stars
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-created by the process of fusion to a silicon core in a range 4 star
-create gamma rays
-over a billion km across
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Globular clusters
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used to determine the locations of the center of the galaxy via observation.
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Interstellar medium
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very hard to detect but when located between us and a distant star it causes light to redden by scattering the blue light particles.
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interstellar reddening
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the process in which dust scatters blue light out of starlight and makes the stars look redder
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Milky Way
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Size:100000 light years across. 1000 light years "thick"
# of stars: 10^11
Rotating disk shape with the Glalatic Nucleus in the center.
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Neutron Star
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created from the left overs of a supernova. 1 tsp is a billion tons. has a quark core with an outside made up of a mix of protons and electrons.
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No-Hair Theorem
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Collapse of neutron core sends the magnetic field radiating away in waves. 3 classical macroscopic quantities remain 1. mass 2. spinrate (angular momentum 3. electrical charge.
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nuclear bulge
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dense concentration of stars around the center of the galaxy
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Pauli Exclusion Principle
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- electrons can occupy the same orbital only if they have opposite spins
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Postulates of Special Relativity
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1. the laws of physics hold everywhere in space
2.The speed of light is the same value for all observers
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Postulate of General Relativity
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Equivalence Principle. there is no difference between a person standing on earth and a person standing on a rocket ship accelerating at 1 G in space.
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Protostars
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not massive enough for nuclear fusion, however it does glow in infrared region due to build up of pressure.
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Pre-Main-Sequence Star
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Gravity causes it to contract not growing in mass but growing in density.
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Main-Sequence star
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once temps reach 10 million Kelvin nuclear fusion begins.
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Pulsars
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Blast of radiation from neutron star.
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General Theory of Relativity
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Explains the relationship between the geometry of space and the flow of time in our Universe
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Roche Limit
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The smallest distance at which a natural satellite can orbit a celestial body without being torn apart by the larger body's gravitational force.
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Keplerian Rotation Curve
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velocity slows as the radius increases
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Solid body Rotation
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velocity increases with an increase in radius. (merry-Go-Round)
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Roy Kerr
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named rotating black holes after him
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Schwarzchild's Contributions
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first to determine the size of the even horizon for a non-spinning slack hole this distance is called the schwartzchild radius
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Shell Fusion reactions and products
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iron core, silicon middle layer and magnesium outter layer
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Spin-Flip radiation of hydrogen
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when the protons and electrons change their spin and give off a photon which is 21 cm in wavelength.
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Stellar Lifetimes
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-Lifetime = Energy Supply / Consumption
-change temperature to mass
-luminosity-temperature-radius relationship
-burns faster, live shorter, burn slower, live longer,
-more mass = shorter life
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Stephen Hawking
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discovered Hawking Radiation is how eventually all black holes will evaporate.
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Supernova Type II
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produced through the death of a high mass star. A Balmer series Spectra is produced
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Supernova Type Ia
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begin as a binary with a white dwarf and a Giant. When matter from the white dwarf is pulled into the giant it eventually exceeds teh Chandrasekhar limit and gravity wins over electron degenercy pressure. Collapse due to gravity, core bounce, outward shock wave and you have a Type Ia supe…
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Superstrings
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the leading framework for Quantum Gravity. Quantum Theory of Gravity is needed to describe the inner structure near the singularity of a black hole
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Synchrotron Radiation
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electrons trapped by eithe rmagnetic field or gravitational field spiraling inward produce synchrotron radiation.
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Temperature for fusion reactions
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Hydrogen @ 10 mill prduces Helium.
Helium @ 100 mill prduces Carbon and oxygen.
Carbon @ 1,000 mill produce neon and magnesium.
Neon @ 1.2 Bill produces silicon and sulfur
Oxygen @ 1.5 bill produces phosphorus.
Silicon @ 2.7 bill prduces Iron
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Variable Stars
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main sequence stars that are in the process of evolving into Supergiants or Giants
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Worm Holes
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tunnels that travel through higher dimensional space called Hyperspace
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X-ray Bursters
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Binary with 1 at least a Neutron star the other is typicall a main sequence star
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AST 105: Final