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53 Cards in this Set
- Front
- Back
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Definition of Planet
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Orbits around the sun
Enough Mass to Assume Hydrostatic Equilibrium (nearly round shape) Clear the neighborhood (no other surrounding bodies same size except satellites or those under gravitational force of planet) |
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Definition of Dwarf Planet
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Orbits around the sun
Enough Mass for Hydrostatic Equilibrium DOES NOT clear he neighborhood |
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Possible Origins of Moons
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1) Conformation: Formed along with the planet and out of the same material as the planet
Example: Jupiter's inner satellite 2) Fission/Collisional Ejection: Moon Breaks off from the original parent body. Can only happen if there is a collision with a very large object. Example: earth's moon which came from a collision 3) Capture: gravitational field captures orbiting debris. Collide or missed collision with third party within gravitational reach of planet Example: Captured Asteroids |
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Synchronous Orbits
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the rotation of a body with a period equal to its orbital period; also called 1 to 1 spin orbit coupling
LOOK UP MORE ON TIDAL EFFECTS |
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Orbital Resonance
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The resonance that occurs whenever the orbital periods of two objects are related by a ratio of small integers
Rhythmic gravitational interactions in an orbital resonance can have stabilizing or destabilizing effect |
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The Roche Limit
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The smallest distance from a planet or other object at which a second object can be held together by purely gravitational force
Example: Ring particles |
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Asteroids (what they are made of)
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Small objects with various mixtures of ice, rock and metal
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Asteroids (where they are found)
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Orbit the sun between Mars and Jupiter
Between 2 and 3.5 AU |
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Typical Size of Asteroids
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Majority of asteroids are smaller than 1km across
700,000 to 1.7 Million are greater than 1km 200 are bigger than 100km Pallas and Vesta are 500km Ceres is 975km |
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Number of Asteroids
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100,000
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Kirkwood Gaps
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Gaps in the spacing of asteroid orbits
MORE |
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Plutinos
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100 objects in the Kuiper belt that orbit the Sun with nearly the same semimajor axis as Pluto
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Edgeworthe-Kuiper Belt
(Location - Layout - Typical Objects) |
30 to 50 AU Orbits in or fairly close to the ecliptic plane. Objects tend to be larger some are dwarf planets 70,000 objects greater than 100km |
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Oort Cloud
(Location - Layout - Typical Objects) |
extends in 3 dimensions from the sun in a total distance of 50,000 AU
composed of chunks of ices with a total mass of about 40 ties that of Earth Largest objects are only a few km across |
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What becomes of meteroids?
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They burn up in the atmosphere or enter in the form of a meteorite
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Comets
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a small body of ice and dust in orbit around the sun. While passing near the sun, a comet's vaporized ices give rise to a coma and a tail
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Comet tails
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The gases burning off as the frozen ice moves closer to the sun
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Photosphere
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Thin Layer (300-500 km thick)
Surface from which visible light escapes Temperature is 5800K but varies dropping to nearly 4400K near top Continuous spectrum emission, but with some absorption near upper layers Granulated (convection cells) Periodic sunspot activity |
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Chromosphere
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Thin layer, but several times thicker than photosphere (2000 km thick)
Temperature varies: 4500K-25000K Very low density, Hot thin gas. Red/Pink colored layer due to strong H emission line spectrum Spicules - short lived spikes or jets of gas shooting up a few thousand km |
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Corona
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Very diffuse and very large, outermost layer of sun
3000 to 10000km above photosphere Irregular shape determined to some extent by solar magnetic field Extremely high temperature (a few million degrees K) Source of sun's UV and XRay emission Sporadic holes that are believed to be corridors for the solar wind |
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Thermal Equilibrium
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Temperature at each depth in sun's interior remains constant even though each depth has different temperature from the others
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Hydrostatic Equilibrium
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the balance between the weight of a layer in a star and the pressure that supports it
Forms spherical design |
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Helioseismology
And how that determines sun's composition |
By measuring the oscillations of the sound waves generated through the sun, a better understanding of the interior's composition is created
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Sunspots
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Dark, irregular-shaped region on the photosphere of the sun
It only appears dark because of the contrast with the surrounding photosphere Photosphere - Temperature of 5800 K and Sunspot is 4300K They occur where photosphere's magnetic field is significantly stronger than that of surrounding photosphere Traps solar plasma and keeps it cooler/darker Come in groups/pairs with opposite polarity |
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Solar Cycle
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Periodic change in sun's activity and appearance. Duration of 11 years
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Sun's Source of Energy
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Hydrogen Fusion into Helium
Thermonuclear Fusion |
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How long will sun shine
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6 million more years
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Thermonuclear Fusion
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Requires very fast atoms, therefore very hot temperatures
Also requires very high density, which means high pressures Can only occur in the interior core of sun and has been mimicked in thermonuclear weapons and for brief instants in plasma fusion rings |
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The solar neutrino problem
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Discrepancy between theoretical predictions of Sun's neutrino output and actual measured value
Recent experiments shows that solar neutrinos change species while in flight between Earth and Sun (neutrino oscillation). These neutrinos were previously undetected due to technology |
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Why fusion is hard to start and maintain
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Temperature is too hot
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How distances to stars are measured
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d = 1/parcsec
1 parc sec = 3.26 ly |
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parallax
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the apparent displacement of an object due to the motion of an observer
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parcsec
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3.26 lightyears
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light year (distance)
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distance light travels in a year
MORE |
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Luminosity
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the rate at which electromagnetic radiation is emitted from a star or other object
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Luminosity connection to temperature and surface area
And thus to Sun's radius |
brightness = Luminosity / 4 pi (d^2)
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Inverse Square Law
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the apparent brightness of a light source varies inversely with the square of the distance from the source
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Principal Spectral Classes
Color, Temperature, Spectral Lines |
O - Blue Violet - 30,000-50,000K - Ionized Atoms, helium
B - Blue Violet - 11,000-30,000K - Neutral helium, some hydrogen A - White - 7500-11,000K - Strong hydrogen, some ionized metals F - Yellow White - 5900-7500K - Hydrogen and ionized metals G - Yellow - 5200-5900K - Both neutral and ionized metals, especially calcium K - Orange - 3900-5200K - Neutral Metals M - Red Orange - 2500-3900K - Strong titanium oxide and some neutral calcium L - Red - 1300-2500K - Neutral potassium, rubidium, cesium and metal hydrides T - Red - 700-1300K - Methane, strong neutral potassium and some water Y - Red - Below 600K - Possibly ammonia |
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Spectroscopic Parallax
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distance to a star derived by comparing its apparent brightness to a luminosity inferred from the star's spectrum
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Role of binary stars in determining masses
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Mass = Semimajor axis (AU) ^3 / Period (in years) ^2
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Mass-Luminosity Relation
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There is a precisely known mathematical relation between luminosity and mass.
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Birth of stars from interstellar clouds
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Gravitational force prevents hydrogen and helium atoms from flying away
The cloud begins to contract if cloud is big enough Cloud heats up Cloud falls into itself to compensate from energy radiated away due to being a black body Contracts more and more and gets hotter and hotter |
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How low mass stars live and die
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The whole star becomes depleted in hydrogen all at once
It will get hotter but no further fusion will occur Becomes black dwarf |
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origin of planetary nebulae
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The ejected outer envelope left over after helium shell burns and white dwarf formed
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origin of white dwarfs
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small but intense white-hot ember that is left over after the helium shell burns off
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How high mass stars die
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Core Collapse
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Synthesis of Elements
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elements heavier than iron. Only phenomena in the universe that can create them.
Stable nuceli will stay and unstable will decay |
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origin of neutron stars
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continued contraction and shrinks past the white dwarf region.
Carbon to Silicon and then Iron. But no energy can be gained from Iron. |
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Degeneracy Pressure
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physical force that can withstand gravity
of electrons |
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Chandrasekhar Limits
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Any white dwarf with mass less than 1.4 AU will stay white dwarf
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What happens if Chandrasekhar Limits are exceeded
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Type 1a super novae
Carbon detonation super novae |
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Difference between Type 1a Super Nova and Type 2
(Both in spectrum and mechanism) |
Type 1a: no hydrogen emission lines
Carbon Detonation (carbon and oxygen) Little or no material around core Type 2: strong hydrogen emission lines Core Collapse within a star that has much of its outer layers |
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Pulsars
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a pulsating radio source thought to be associated with a rapidly rotating neutron star
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