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33 Cards in this Set
- Front
- Back
Clouds of nebular gas are
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90% H, 9% He, 1% other
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Collapse of dust and gas is initiated by
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Shock waves from:
stellar wind of nearby heavy stars supernova explosion |
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New star formation is associated with
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Open/galactic clusters
OB associations HII regions (regions of ionized gas) ex: Orion nebula |
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Stellar association
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Loosely bound group of new-born stars
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Absorption nebula
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Cloud of dust and gas which obscures more distant light ex: Horsehead nebula
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Reflection nebula
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Cloud of dust illuminated by stars (blueish)
ex: Pleiades |
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Emission nebula
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Glowing from excitation caused by nearby stars
ex: Orion nebula |
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Brown dwarf
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Failed star. If the mass is less than 0.08 Msun, it never gets hot enough for thermonuclear fusion
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10 x 10^6 K
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Proton-proton chain
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20 x 10^6 K
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CNO cycle
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100 x 10^6 K
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Triple alpha
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600 x 10^6 K
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Carbon-helium fusion
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10^9 K
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Carbon burning
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Main sequence phase ends when
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Core hydrogen burning ends
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Helium burning
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When core reaches 100,000,000 K, helium fuses to carbon (triple alpha process)
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Helium flash
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Runaway helium fusion initially for stars with mass less than 3Msun
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Red giant
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Very bright, enlarged star
ex: Betelgeuse |
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Planetary nebula
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25%-60% of the star is ejected, white dwarf may soon appear in the middle
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White dwarf
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Spent low-mass star, cools slowly, no longer generate energy
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Chandresekhar Limit
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Less than 1.4 Msun, degenerate electron pressure, density = 10^9 kg/m^3
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Black dwarf
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After the white dwarf cools and dims. A cold, dense, burned-out ember in space
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Type I supernova
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Binary system, carbon-detonation supernova, white dwarf grows from accretion of material from companion, eventually exceeding Chand mass limit
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Type II supernova
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Single massive star, core-collapse supernova, massive star expends its fuel supply, ending with iron core, and collapses and explodes. Not in Milky Way
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Neutron stars
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Extremely dense stellar matter, diameter of 30 miles
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Pulsars
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Pulsating radio source produced by rapidly rotating N-star
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Close binaries
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Stars separated by few stellar diameters
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Critical surface
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figure eight-shaped boundary around star defining gravity domain. Two lobes called Roche lobes. If it collapses it will result in mass transfer
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Blue stragglers
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Stars found in globular star clusters which have not evolved as much as comparable massive stars. Results from mergers of lower mass stars which delayed the normal evolution of the massive star
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Neutrinos
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No charge, very little particle mass, hardly interacts with anything, very hard to detect, travels at nearly the speed of light
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Pauli Exclusion Principle
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You can't have two things (electrons) in the same place at the same time
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Horizontal Branch
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Post-helium flash stars on the H-R diagram
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Young clusters
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Metal rich. Population I. Open/galactic cluster
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Old clusters
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Metal poor. Population II. Globular cluster
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