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PH 109 Final Part 2
| Question | Answer |
|---|---|
| What causes the outward pressure that balances the inward pull of gravity in a black hole? | nothing |
| Most of the elements that make us up | were produced in supernovae |
| What is the single most important characteristic in determining the course of a star's evolution? | Mass |
| Red stars are ____ than blue stars | cooler |
| What causes the outward pressure that balances the inward pull of gravity in a normal star? | The outward flow of energy |
| What is the correct sequence of spectral types of stars according to temperature? | OBAFGKM |
| Synchrotron radiation is produced by | high-velocity electrons moving through a magnetic field |
| A _____ is a city sized star supported by degenerate neutrons | neutron star |
| When material expanding away from a star in a binary system reaches the Roche surface | the material is no longer gravitationally bound to the star. |
| About how old is our sun? | 5 billion years |
| If the Sun were replaced by a black hole having one solar mass, what would happen to the Earth's orbit? | the Earth's orbit would remain the same |
| You can tell the age of a star cluster by | using the HR diagram |
| the spectral type of a star measures its | temperature |
| a star's luminosity depends only on the star's | temperature and diameter |
| In relative terms, how does the Sun's temperature compare to all other stars? | tends to be in the middle |
| The observed slowing of a clock in the vicinity of a black hole is a prediction of | general relativity |
| an emission nebula | is a region producing emission spectra |
| The total mass of a binary system can be calculated from | the semi major axis and period of the orbit |
| What mechanism is most responsible for the twisting of the Sun's magnetic field lines? | differential rotation |
| The centers of solar granules | are hot material rising to the photosphere from below |
| The best way to observe cool Hydrogen atoms is | 21 cm radiation |
| The heaviest element that stars can produce in their cores is | Iron |
| What causes the outward pressure that balances the inward pull of gravity in a neutron star? | the degenerate pressure of neutrons |
| How long does it take Sunlight to reach the Earth? | 8 minutes |
| A star that has failed to gain enough mass to initiate fusion is | a brown dwarf |
| What star is the most dense? | a white dwarf |
| Reddening refers to | scattering of blue light by dust |
| a planetary nebula is | last gasp of a dying solar type star |
| What do Helioseiemologists study? | the ringing Sun |
| In the twin paradox | the faster twin lives longer |
| by what factor would the brightness of a star increase if an observer moved from 4 parsecs to 1 parsec from the star? | 16 |
| The two most abundant elements in the sun are | hydrogen and helium |
| Of all the stars that are currently on the main sequence, which spectral type would be least abundant? | B |
| What explanation does general relativity provide fro gravity? | gravity is a result of curved space time |
| What is curious about jets? | that they remain collimated over large distances |
| a neutron star is expected to spin rapidly because | they conserved angular momentum when they collapsed |
| Sunspots appear dark because | they are cooler regions |
| What nuclear fuels does a one solar mass star use over the course of its entire evolution? | hydrogen and helium |
| The radio emission from radio galaxies and quasars is due to | synchrotron radiation |
| What type of galaxy is the Andromeda galaxy M31? | spiral |
| About how long does it take for the Sun to complete one trip around the galaxy? | 250 million years |
| Quasars were originally discovered as | strong radio sources identified with star-like images on photographs |
| When galaxies collide | they simply perturb each others shape |
| The mass of a single galaxy might be found by | the rotation curve method |
| Why is the energy source of active galaxies thought to be extremely compact? | Their spectra are like those produced by ordinary stars. |
| Most of the mass of a galaxy is | contained in the dark matter of the galaxy |
| What kind of galaxy do we live in? | Spiral |
| How do we determine the masses of galaxies? | Kepler's Law |
| The true distribution of galaxies is | grouped in filaments, voids and clusters of galaxies |
| As matter streams in a black hole it usually forms what kind of structure? | accretion disk |
| 21 cm radiation is produced by which element? | hydrogen |
| What was Klemperers dream about? | colliding galaxies |
| The distribution of galaxies in the universe are | arraigned on the surfaces of giant bubbles or voids |
| It is unlikely that astronauts will ever pass through black holes because | tidal forces would rip them apart |
| About what percentage of the mass in the galaxy is "dark"? | 90% |
| If our galaxy has a black hole at its center then why do we not see jets? | It has consumed all available matter |
| Why are quasars called quasi-stellar? | They look like stars on photographs |
| Most of the mass of a galaxy is | contained in the dark matter of the galaxy |
| Which kinds of galaxies appear to have black holes at their centers? | All |
| What good are 21 cm radio waves to galactic astronomers? | Their Doppler shifts let us map the motions and locations of Hydrogen |
| Which type of galaxy contains the least amount of interstellar material? | Ellipticals |
| What type of galaxy is frequently found at the center of a rich cluster of galaxies? | elliptical |
| What is hardest to explain about spiral arm structure? | how they maintain themselves |
| What is the name of the nearest large galaxy to our own? | Andromeda |
| A rotation curve for a galaxy is a plot of | orbital speed versus distance from center |
| What is the most likely source of energy for active galaxies and quasars? | Accretion onto a super massive black hole |
| The location of our Sun in the galaxy is approximately | about 2/3 of the way out to the edge |
| Why are the supermassive giant ellipticals found at the centers of the rich galaxy clusters? | Such giants are the result of many mergers, cannibalizing smaller neighbors. |
| An Einstein ring and cross represent examples of | distorted images |
| Hubble's law describes a relationship between a galaxy's | redshift velocity and distance |
| For what type of object is the period-luminosity relation used for determining distances? | Cepheids |
| Our galaxy has two smaller galaxies in orbit around it which are called | Magellanic clouds |
| In what part of the spectrum can astronomers observe the 21 cm radiation? | radio |
| What kind of galaxy has a rotation curve that does not fall off according to Kepler's laws out past the visible end? | All |
| We can map out the distribution of dark matter by | gravitational lensing |
Created by:
emulligan
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