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48 Cards in this Set
- Front
- Back
Stars form in ___ , ____ interstellar clouds
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Cold, Dense
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Dark Nebula-
What does it do? |
Dense cloud of gas and dust
Absorbs visible light + Obscures Stars Behind It |
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1) What happens when a could collapses?
2) What triggers a collapse? 3) What happens when it contracts? |
1) Gravity causes cloud to collapse if it is compressed by a shock wave, and it goes out of hydrostatic equilibrium
2) Nearby Supernova, Cloud passing through spiral arm of galaxy, cloud collision 3) Gas is heated + compressed |
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1) Protostars are formed and surrounded by what?
2) What are they best observed in? Why? 3) What happens when the star is on main sequence? |
1) dense gas and dust clouds from which they form
2) Infrared, less absorbed by dust than visible light 3) It stops contracting |
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1) What is reflection Nebulae?
2) Why is it blue? 3) Do stars behind dust appear redder? |
1) bluish haze seen around hot, young stars due to interstellar dust.
2) b/c dust reflects blue light more effectively than right light 3) YES |
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1) Interstellar Reddening is what?
2) Light reflected by dust cloud appears what? |
1) when dust clouds b/w star and observer scatter more blue light that red light out of beam
2) Blue |
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1) Why is the Earth's sky appear blue?
2) Why does the Sun look red when near the horizon? |
1) because air molecules reflect more blue than red light
2) Because more blue light than red light has been removed |
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1) What are the main sequence mass limits?
2) Why are these the limits |
1) From .08 MoS to 100 MoS
2) <.08 is too low to fuse, >100 pressure blows star apart |
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Evolution of a 1 MoS Star
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1) Main Sequence
2) Red Giant 3) Helium Flash 4) Horizontal Branch 5) Second Red Giant 6) Planetary Nebula 7) White Dwarf |
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1) What happens when a star leaves the main sequence?
2) How long does the sun spend on the Main Sequence? |
1) It leaves when H is used up in core from H Fusion
2) 10^10 Years |
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1) What happens to a star in the Red Giant Phase?
2) Outer region of star ____ and ___ |
1) H fusion ends in core, but continuous in shell around core. Gravity causes core to contract and heat.
2) expands, cools |
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1) Red Giant is B___, B____, and C___
2) What happens in a Helium Flash? 3) What is the triple-a process? |
1) Big, Bright, Cool
2) Central T= 10^8 K, He fusion begins in core. 3) 3He ---> C + energy, C= carbon nucleus. |
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1) What happens in the Horizontal Branch Phase?
2) L is _____ than for sun 3) What do they form in the HR diagram |
1) He Fuses to C in core, core expands and cools, envelope contracts and becomes bluer.
2) Higher 3) Horizontal grouping |
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1) What happens in the Second Red Giant Phase?
2) The Core ___; envelope ____ |
1) No He left in core, core is now Carbon (C), No nucleur fusion occurs in core
2) Contracts, expands |
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Structure of ejected gas can be non-spherical due to....
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- Star orbiting a binary companion
- or a disk around star- produces hourglass shape |
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1) What happens in a White Dwarf Phase?
2) What is the structure? 3) Does it contract anymore once a white dwarf? |
1) Hot, dense core becomes white dwarf= collapsed star about size of Earth, NO nuclear burning
2) Very Dense (10^6 X density of water). Electrons are packed as closely as possible. 3) NO, T and L decrease in time |
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1) What happens in the Planetary Nebula Phase?
2) What is the structure like? 3) Is it related to planets? |
1) Envelope pulsates unstably. Envelope is ejected, core exposed.
2) Expanding spherical gas, Shell around small, hot star, appears as bright ring sky. 3) NO, but it may look like a planet when using a small telescope |
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1) What is the Mass Limit for White Dwarf? Discovered by who?
2) What happens when this mass limit is breached? 3) What are more highly collapsed stars? |
1) 1.4 MoS, Chandra
2) gravity overcomes electron pressure and then collapse to smaller size and higher density. 3) Neutron Star, Black Hole |
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1) Where are open star Cluster's found? And how can you describe them?
2) Where are most of the stars? How old? |
1) in disk of Galaxy (i.e. Pleiades), young, recently formed stars.
2) Near main sequence, 2X10^7 Years |
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1) Where are globular star clusters found? And how can you describe them?
2) They have moved to next ____ |
1) Found in bulge/halo of our galaxy, contain only old stars >10^10 years
2) Phases |
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1) The younger the cluster, the ____ the mass of the turnoff stars
2) The ____ of the turnoff determines the ___ of the cluster |
1) higher
2) location, age |
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1) In High Mass Stars what happens in nuclear fusion?
2) Core is only the size of ____ |
1) Produces elements up to Iron, growing iron does NOT undergo fusion
2) Earth |
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1) What happens in a supernova?
2) What type of particles are produced? And in what way? |
1) Gravity overcomes outward electron pressure in iron core, causing rapid collapse. Electrons and protons combine to form neutrons.
2) Neutrinos, through a pulse |
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1) What happens in a supernova blast?
2) What types of elements are produced? |
1) Energy released by core collapse causes shock wave to travel out.
2) Elements heavier than iron |
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1) Elements heavier than H and He are produced in ____ stars, where do they go?
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1) Massive, Return to interstellar gas
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1) What are some observations of Supernova 1987A?
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1) Blue supergiant exploded, L increased by a few 1000X, Neutrino Pulse seen in 2 underground detectors- confirmed stellar core collapse
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1) What does the Chandra X-ray provide?
2) What is the central source for the X-ray? |
1) Provides much more detail than previous x-ray telescopes.
2) Neutron Star formed in supernova |
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1) What are neutron stars?
2) Neutron Stars are _____ , ____ gas 3) What do they emit? |
1) ultra-collapsed stellar cores, produced by SuperNova, made of tightly packed neutrons.
2) expanding, hot 3) all forms of EM radiation: radio - gamma rays |
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1) What is pulsar? How was it discovered?
2) What was the first explanation? |
1) pulsing source of radio, visible, or X-rays. By using radio telescope in 1967.
2) alien signals |
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1) Pulsar Model is a...
2) What are not aligned? 3) What is the radiation beamed along? 4) Lighthouse Effect- |
1) Magnetized, rapidly rotating neutron star.
2) Magnetic and rotation axis 3) The magnetic axis 4) see flash when beam sweeps past us |
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1) Why is Rotation so fast?
2) As core collapses spin rate ____ |
1) "Ice Skater Effect"
2) Greatly Increases, fastest =42000 |
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1) How are accretion disks formed?
2) What happens to gas in the disk? |
1) When gas escapes from normal star and is attracted by gravity of collapsed star and then it forms
2) it spirals inward, releasing gravitational energy, then heated to High T by friction and radiaties UV and X-ray |
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1) What is the maximum mass for a neutron star?
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1) 3 MoS
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1) What is Cygnus X-1
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Visible star is B supergiant with strong wind, it is a Black Hole M= 5-10 MoS
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1) What is a black hole?
2) What happens to its density? |
1) Object with such strong gravity that NOTHING can escape from its vicinity- even light
2) It has infinite density- a singularity |
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1) Explain Curved Space
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1) Mass causees space to curve. High mass concentration caused surrounding space to pinch off from rest of universe, nothing can escape from this region.
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1) What is the event horizon?
2) What happens to something that goes into event horizon? 3) What is the escape speed? |
1) Location of BH surrounded by spherical surface. "Sphere of no escape"
2) merges into BH, and increases event horizon and BH mass 3) faster than speed of light |
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1) Photons follow ___ paths in curved space
2) The more collapsed a star, the more it ____ the surrounding ____ |
1) Curved
2) curves, space |
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1) Where are Black Holes located?
2) How do BH's power active galaxies and quasars? |
1) In binary star systems (we have about 20) and at centers of galaxies
2) through gravitational energy release |
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What are the properties (endstate,mass,Radius) of stars with...
1) M<10 MoS 2) M>10 MoS 3) M>25 MoS |
1) white dwarf, 1.4 MoS, Radius of Earth
2) neutron star, < 3 MoS, 10 Km 3) black hole, > 3 MoS, 9km |
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1) Where is the sun located in the Milky Way?
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1) in the disk, left of the galactic center from top view, midway b/w center and edge
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1) When looking at the Milky Way through Infrared, compare the wavelength of Dust and Stars and their Temp
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1) Dust- Longer Wavelength IR, LOWER T. Stars- Shorter Wavelength IR, HIGHER T
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1) What is the shape of the Milky Way?
2) How many LY's in diameter, thickness? |
1) Disk, Frisbee shaped
2) 100,000 LY, 2000 LY |
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1) What paths do stars and gas follow in the disk.
2) What is the orbital period of the sun? 3) How many orbits has it completed? |
1) Circular orbits (like planets)
2) 2X 10^8 Years 3) Age/Period= 25 orbits |
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1) What happens in the evolution of the disk with respect to each stellar generation?
2) Do young or old stars have high metal content in the atmosphere, why? |
1) Each generation adds "metal" to interstellar gas, from supernova explosions
2) Young because they are formed from enriched gas |
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1) Give details about the Halo
2) What are the motions like in the spheroid? |
1) It is spherical and extends well beyond disk, contains individual stars, global star clusters, and dark matter. OLD STARS only- no gas and dust
2) no common orbital plane or direction |
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1) What did the old view of the galactic center not account for?
2) How did Shapley develop the modern view of the galactic center? |
1) Dust, which obscures distant stars
2) Used globular clusters, and these are found near galactic center |
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1) What is a standard candle?
2) Where is the milky way and the galactic center located? 3) How far is the Sun from the galactic center? |
1) an object of known luminosity
2) Sagittarius 3) 25,000 LY |