ASTR 1020: STUDY GUIDE
198 Cards in this Set
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Gravitational Equilibrium
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When gravitational forces balance pressure forces
Gravity In + Pressure Out = Balance
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Energy source for sun/stars?
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It fuses Hydrogen (H) into Helium (He)
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Fusion vs. Fission
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Fusion - small nuclei stick together to a make a bigger one (H-bomb, Sun, stars use to produce energy)
Fission - big nucleus splits into smaller pieces (nuclear power plants use to produce energy)
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About how much bigger is the Sun than the Earth in size and mass?
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About 109 times bigger than the Earth
About 333,000 times the mass of the Earth
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What is the Sun's surface temperature and core temperature?
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Surface temperature ~ 6,000K
Core temperature ~ 15MM K
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What are the Sun's 3 atmospheric layers?
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Corona - the outermost layer (~1MM K)
Chromosphere - the middle layer; most active area (~104- 105K)
Photosphere - The visible surface (~6,000K)
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What are the Sun's 3 interior layers?
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Convection Zone - energy transported upward by rising hot gas
Radiation Zone - energy transported upward by photons
Core - energy generated by nuclear fusion (~15MM K)
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What is the composition of the Sun/Stars?
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The Sun is a giant ball of gas (or plasma) - a gas in which many of the atoms are ionized because of the high temperature. The differing temperatures and densities of the plasma at different depths give the Sun the layered structure
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Convection vs Radiation?
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Convection Zone - energy transported upward by rising hot gas
Radiation Zone - energy transported upward by photons
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What is temperature a measure of?
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A measure of how fast atoms/molecules are moving
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What is energy?
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The stuff that makes matter move
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What is the conservation of energy concept?
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Energy is conserved - it is never created or destroyed; it just changes forms
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What is the basic atomic structure?
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Photons - have a + charge
Electrons - have a - charge
Neutrons - have no charge
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What is atomic number?
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The # of protons which define what an atom is
Hydrogen (1H) - Atomic # = 1
Helium (4He) - Atomic # = 2
Carbon (12C) - Atomic # = 6
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What temperature is needed to fuse Hydrogen atoms? Why must this temperature be so high?
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~15MM K; must be this high of a temperature because the nuclei must collide at very high speeds if they are to come close enough together to fuse
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Why do fusion reactions release energy? What's this equation to calculate this?
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Final nuclear products are less massive than initial. The mass "lost" was converted to energy (E=MC2)
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How do we know what the interior of the Sun is like?
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Mathematical Models - agree with observed properties (size, luminosity, etc...)
Helioseismology - traces interior structure by observing vibration (similar to seismic activity)
Solar Neutrinos - produced in proton-proton chain agree with predictions
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What causes northern lights?
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Charged particles trapped in the magnetosphere creating light (aurora) located in the Nothern Hemisphere
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What is solar wind?
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a flow of charged particles ejected from the Sun
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Why are sunspots dark?
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They are less bright than the surrounding photosphere because they are cooler; (~4000 K)
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What is the solar cycle?
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A 22-year period for magnetic cycle that has something to do with the winding and twisting of the Sun's magnetic field.
Every time we reach a solar minimum (11 years) the south pole becomes the north pole, vice versa
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What causes solar activity?
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Solar activity is driven by magnetic fields (sunspots, flares, and coronal mass ejections), which form and change easily in the convecting plasma in the outer layers of the Sun
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What are solar flares?
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Huge and sudden releases of energy on the solar surgace, probably caused when energy stored in magnetic fields is suddenly released
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What are Coronal Mass Ejections (CME's)
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Bursts of charged particles from the un's corona that travel outward into space
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Luminosity vs. Apparent brightness
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Luminosity - amount of power a star radiates (energy per second = watts)
Apparent brightness - amount of starlight that reaches Earth (energy per second = per sq. meter)
The relationship between apparent brightness and luminosity depends on distance
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How does brightness change with distance?
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We can determine a star's luminosity if we can measure its distance and apparent brightness
Luminosity = 4 (distance)2 x (brightness)
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What's a parsec (pc)?
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The distance to an object with a parallax angle of 1 arcsecond; approximately equal to 3.26 light-years
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What is a light-year (ly)?
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The distance that light can travel in 1 year, which is 9.46 trillion km.
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What is parallax? How does this depend on distance?
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The apparent shift in position of a nearby object against a background of more distant objects
It decreases as the distance to the object increases
The largest distance you can measure using parallax is 100 pc, which has a parallax of 0.01 arcseconds
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Ways to estimate stellar temperature - color and levels of ionization (seen in spectra)?
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Can't measure directly, but you can infer the surface temperature by star color or its spectrum.
A red star is cooler than a yellow star, which is cooler than a blue star
Spectral Types - (hottest ~50,000K) O B A F G K M (coolest ~3,000K)
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What's the Sun's spectral type?
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G2, which means it is slightly hotter than a G3 star but cooler than a G1 star.
The larger the #, the cooler the star.
Hotter objects emit more light, and emit a bluer light
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How are stellar masses estimated?
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Can't weigh directly, must rely on star's gravitational pull (Newton's version of Keplers 3rd law)
Measure both the orbital period and the avg. orbital distance of the orbiting object - in binary star systems
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What are the 3 types of binary star systems?
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Visual - 2 visibly separated stars and can directly observe the orbital motions of the stars
Eclipsing - can measure periodic eclipses (look like 1 star)
Spectroscopic - determined the orbit by measuring Doppler shifts ( look like 1 star)
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Ranges of luminosities, temperatures, and masses for stars?
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Main sequence stars (dwarfs)
Giants (red)
Supergiants
White dwarfs
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How can a cooler star be more luminous than a hotter star, and vice versa?
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Stars' luminosity depends on both its surface temp and surface area or radius
If a cooler star is larger in size, it will be more luminous than a hotter star, vice versa.
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What is the Hertzprung-Russel (H-R) diagram
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To plot a star, you must know its luminosity and spectral type
X-axis measures surface temp related to spectral type (OBAFGKM)
Y-axis measure luminosity
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What are main sequence stars? Properties and location on H-R diagram?
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The Sun falls along the main sequence, a line of stars extending from the upper left of the diagram to the lower right. Most stars lie here, which shine by fusing H into He in their core (like the Sun)
Luminosity Class = V
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What are Giants? Properties and location on H-R diagram?
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Stars in the upper right of the diagram are more luminous than m-s stars of the same surface temperature. They must therefore be very large in radius (not mass), which is why are known as Giants - Luminosity class = I
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What are SuperGiants? Properties and location on H-R diagram?
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Stars in the upper right of the diagram are more luminous than m-s and giant stars of the same surface temperature. They must therefore be very large in radius (not mass), which is why are known as Supergiants - Luminosity class = III
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What are White Dwarfs? Properties and location on H-R diagram?
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Stars in the lower left have high surface temperatures, dim liminosities, and small radii. Very small and dense. Initially very bright (they are exposed to stellar cores) but have no energy source and slowly cool off in temp becoming less luminous
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Relation between temperature, luminosity, mass, and lifetime for main-sequence stars?
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Stellar masses decrease from the upper left to the lower right on the main seq.
Stellar lifetimes increase from upper left to lower right on the main seq: High mass stars live shorter lives due to high luminosities burn thru nuclear fuel faster
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What's the Sun's lifetime?
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1010 years
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2 things stars in a cluster have in common?
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The stars are all the same age (gives clues to evolution)
They are all the same distance (helps estimate luminosity)
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2 types of star clusters and basic properties?
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Open Clusters - low density cluster (few 1,000), w/ youngish stars, found in galactic plane, stars slowly drifting apart
Globular Clusters - high density cluster (millions), w/ very old stars, found in galactic halo, stars tightly bound by gravity
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What type of star cluster is the Pleiades?
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Globular cluster. The Pleiades has no stars with a lifetime less than ~100MM years.
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How are cluster ages estimated?
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A star clusters' age roughly ='s the life expectancy of its most massive stars still on the main sequence
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What is the Main Sequence Turnoff Point?
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The location where stars diverge from the main sequence, which tells us its age
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What is Interstellar Medium?
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The material (mostly gas and dust) between the stars
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Where do stars form?
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Molecular clouds. Every year, 2-3 stars are formed in our galaxy in these clouds. They form in dark clouds of dusty gas
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Composition of molecular clouds?
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70% Hydrogen
28% Helium
2% heavier elements in our regions of the Milky Way
Temps of 10-30K and a density of ~300 molecules per cubic cm.
Much of the matter is in the form of molecules (H2, CO)
Absorption lines in the spectra of stars revel composition
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Why does interstellar dust make stars look redder (interstellar reddening)?
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Stars viewed through the edges of the cloud look redder because dust blocks (shorter wavelength) blue light more effectively than (longer wavelength) red light.
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When/Will a cloud (fragment) collapse to form a star?
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When gravity causes a cloud to contract, and the contraction continues until the central object becomes hot enough to sustain nuclear fusion in its core
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What is thermal pressure?
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The ordinary pressure in a gas arising from motions of particles that can be attributed to the object's temperature.
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What's the dominant cooling mechanism for molecular clouds?
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Without any significant build up of thermal energy, gravity continues to dominate over thermal pressure, so all parts of the clould that remain cool can contract to form stars
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What evetually slows contraction?
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The build up of thermal energy raising the cloud's temp and its thermal pressure, eventually bringing the process of star formation to a halt and slowing contraction
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Properties of young stars (partially hidden, disks of material, jets)
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dense concentration at the center forms a star
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What's a protostar?
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a clump of gas that will become a new star - look starlike, with surface temps and luminosities similar to those of true stars. Not yet a true star because its core is not yest hot enough for nuclear fusion
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Spiral
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What type of galaxy is the Milky Way?
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A. Thermodynamic
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Which of the following is NOT one of the 4 fundamental forces known?
A. Thermodynamic
B. Weak Nuclear
C. Electromagnetic
D. Strong Nuclear
E. Gravity
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The central black hole clears out a region around it.
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Active galaxies are believed to become less active as they age because...?
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380,000 years
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One of the most important events in the history of the Universe is when radiation and matter decoupled and went their separate ways. About how long after the Big Bang did this happen?
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E. slight differences in the cosmic microwave background
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Which of the following observations tells us about the distribution of normal matter & dark matter in the Universe?
A. the blueshifts of distant galaxies
B. the amount of iron observed in stars
C. the sizes of giant elliptical galaxies
D. the amount of deuterium & helium
E.…
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50 kpc
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The Sun is 8,000 pc from the center of the Milky Way. About how far does it travel by making a circular orbit around the center?
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E. photons travel at a finite speed
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What sets the limit of the observable Universe?
A. photons need no medium to travel
B. photons have wavelengths & frequencies
C. wave/particle nature of light
D. photons come in different types
E. photons travel at a finite speed
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D. the center of the globular cluster distribution was not at the Sun's location
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Shapley discovered that the Sun was NOT in the central bulge of the Milky Way by observing that
A. there is a powerful radio source in Sagittarius
B. Cepheid variable stars were all located in the Large Magellenic Cloud
C. supernovae were bright even in the Andromeda Galaxy
D.…
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B. astrometry
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Which observing technique is used to measure the expansion of the Universe with Hubble's Law?
A. photometry
B. astrometry
C. polarimetry
D. thermography
E. spectroscopy
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A. black holes
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In the future Universe which of the following will be the last type of abundant object with a mass greater than the earth?
A. black holes
B. white dwarfs
C. brown dwarfs
D. positronium atoms
E. neutron stars
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A. Small Magellenic Cloud
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Which is DEFINITELY NOT an example of an active galaxy?
A. Small Magellenic Cloud
B. Seyfert galaxy
C. radio galaxy
D. quasar
E. giant elliptical galaxy with a jet of ejected matter
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B. expand forever
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Current observations of the Universe indicate that in the distant future the Universe will
A. be heated to tremendously high temperatures
B. expand forever
C. condense into one giant elliptical galaxy
D. remain closed & collapse
E. show blueshifted galaxies
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C. Aldebaran B
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Which of the following stars on the research list would be the last to convert hydrogen to helium?
A. Alpha Centauri A
B. Alpha Centauri B
C. Aldebaran B
D. Antares A
E. Antares B
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E. quasars
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Which of the following objects is NOT found in the disk of the Milky Way?
A. brown dwarfs
B. RR Lyrae stars
C. open clusters
D. black holes
E. quasars
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A. an image of the 0.02 AU event horizon has been obtained
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Which of the following is NOT a reason why we believe there is a supermassive black hole in the center of the Milky Way?
A. an image of the 0.02 AU event horizon has been obtained
B. extended filaments of gas are seen
C. fast light flickering indicates a very small size
D. a b…
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500 megaparsecs
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If Ho = 70km/sec/Mpc, and the velocity of a quasar is measured to be 35,000 km/sec, about how far away is it?
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Velocity & Distance from the Center
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What are the labels on the two axes of a galaxy rotation curve graph?
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C. masses
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Spiral and elliptical galaxies can be separated based on all of the following EXCEPT their
A. amount of dust & gas
B. ratio of disk size to halo size
C. masses
D. number of arms
E. ages of the stars in them
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E. mass
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Which attribute of a black hole is needed to determine the radius of its event horizon?
A. luminosity
B. speed of light
C. spectral type of a companion star
D. temperature of accretion disk
E. mass
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E. Milky Way Disk
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Stars with the largest fraction of elements heavier than hydrogen and helium can be found in
A. Milky Way bulge
B. globular clusters
C. Milky Way halo
D. quasars
E. Milky Way Disk
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C. the masses of neutrinos
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Which is NOT an observation that tells us that dark matter exists?
A. velocity of the Sun around the Milky Way
B. gravitational lensing of distant quasars
C. the masses of neutrinos
D. velocities of galaxies in the Virgo Cluster
E. rotation curves of nearby galaxies
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B. Era of Atoms
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Which of the following Eras DID NOT occur before matter & radiation decoupled and went their separate ways?
A. GUT Era
B. Era of Atoms
C. Electroweak Era
D. Era of Nucleosynthesis
E. Planck Era
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B. red giants
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Which is NOT a candidate for the missing mass in the halo of the Milky Way?
A. black holes
B. red giants
C. brown dwarfs
D. subatomic particles (WIMPS)
E. faint red dwarf stars
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D. 1000 microns
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The temperature of the microwave background is 2.73 Kelvin and its spectrum follows a blackbody curve. At about what wavelength does the spectrum reach peak?
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...
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When combined, the amount of observed normal matter & inferred dark matter (we know that it is there, but we don't know what it is) amounts to about what percentage of that required to close the universe?
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...
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Phase of the moon now? Phase of the moon in a week? etc.
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E. H
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Which element causes the 21-centimeter line used to map gas in the Milky Way?
A. N
B. C
C. Si
D. He
E. H
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3
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How many total helium nuclei are required to make a single carbon nucleus?
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B
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Rank the following process in order of the heaviest elements created (A = lightest elements produced, E = heaviest elements produced).
21. triple alpha process
22. r-process
23. proton-proton chain
24. s-process
25. helium capture
A, B, C, D, E
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A
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Rank the following from the most massive (A) to the least massive (E).
26. giant molecular cloud
27. red dwarf star of spectral type M
28. Earth
29. neutron star
30. Sun
A, B, C, D, E
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B. 6
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How many total protons, electrons, and neutrons are there in a neutral helium atom?
A. 3
B. 6
C. 9
D. 10
E. 12
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D. 4
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How many net hydrogen atoms does it take to make a helium atom inside the Sun?
A. 1
B. 2.
C. 3
D. 4
E. 5
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A. O
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Which spectral type of star is the hottest?
A. O
B. F
C. A
D. M
E. G
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C. 6
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To about what faint magnitude do most human eyes reach in a clear, dark, night sky?
A. 30
B. 0
C. 6
D. 18
E. -1
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D. 7
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What element number is nitrogen?
A. 4
B. 5
C. 6
D. 7
E. 8
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...
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What is the phase of the Moon right now?
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B. the orientation of our Solar System relative to the plane of the Milky Way
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Which is NOT an observation that tells us how galaxies formed? (meaning that all of the other DO tell us something)
A. there are more spirals observed at high redshift
B. the orientation of our Solar System relative to the plane of the Milky Way
C. some galaxies show evidence of …
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A. the Universe inflates very rapidly
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Which of the following events happened first?
A. the Universe inflates very rapidly
B. the Universe is made up of brown dwarfs, white dwarfs, neutron stars & dark matter
C. the cosmic microwave background observed to have a temperature of 2.73 degrees Kelvin
D. the first galax…
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B. the existence of the cosmic microwave background
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The best DIRECT proof that the Big Band occurred is
A. black holes are often found in the centers of galaxies
B. the existence of the cosmic microwave background
C. we live in a Universe of matter, not antimatter
D. most stars are red dwarfs
E. the amount of primordial deut…
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8 times brighter
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Pretend that a small red star is on a collision course with us. As if moves from 4 parsecs away to only 1 parsec away, how does the brightness change?
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B. the Milky Way and Andromeda are excellent examples of active galaxies
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Which is NOT true about active galaxies?
A. quasars are distant, young, active galaxies
B. the Milky Way and Andromeda are excellent examples of active galaxies
C. they are powered by massive black holes at their centers
D. Seyfert galaxies are a type of active spiral galaxy
…
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C. are unstable and change size
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Cepheid and RR Lyrae type stars are variable because they
A. are in eclipsing binaries
B. are burning different fuels quickly
C. are unstable and change size
D. are evolving quickly through various evolutionary stages in the HR diagram
E. have large spots on their surfaces…
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- 21
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The Andromeda Galaxy is determined to have an apparent magnitude of +4. It is measured to be about 1 million parsecs away. What is its absolute magnitude?
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lower Temperature, lower density, fewer interactions between particles and photons
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The overall fundamental changes in the Universe as it expands include...
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B. Andromeda Galaxy
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At which object would you look to see the furthest back in time?
A. a globular cluster in the Milky Way halo
B. Andromeda Galaxy
C. Alpha Centauri
D. Pluto
E. Large Magellenic Cloud
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D. neutrinos & photons (things that don't react)
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In the absolute bitter end of the Universe (assuming it will expand forever) all that will be left are
A. protons, neutrons, & electrons
B. dead white dwarfs known as black dwarfs
C. clusters of black holes
D. neutrinos & photons
E. your notes from Astronomy 1020
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E. distance of redshifted supernovae
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What observations seem to indicate that the expansion of the Universe is accelerating?
A. COBE & WMAP observations of the cosmic microwave background
B. magnetic field strength in active galaxies
C. rotation curves of nearby galaxies
D. arcs of lensed light from distant quasar…
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14 billion years
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According to current scientific understanding, about how old is the Universe?
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B. the inflationary event
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Which of the following explains why the Universe appears to have a density near the "critical" density, AND why the cosmic microwave background appears so smooth?
A. dark energy
B. the inflationary event
C. matter annihilates antimatter, but some matter is left over
D. the rat…
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100,000 times longer
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How long will a red dwarf last relative to our Sun, if the red dwarf has a mass of 0.1 Msun and luminosity 10-6 Lsun?
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D. Rigel
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If all of the following stars on the research list were in the Andromeda Galaxy, which would appear brightest from Earth?
A. Arcturus
B. Betelgeuse
C. Capella
D. Rigel
E. Vega
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Rigel A
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Which of the stars on the research list is largest?
A. Rigel A
B. Arturus
C. Antares B
D. Procyon B
E. Pollux
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C. light curves of variable stars
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Matching objects observed to the techniques used to measure distances in the Universe.
A. radar
B. astrometry to measure trigonometric parallax
C. light curves of variable stars
D. Hubble's Law
E. photometry of suddenly bright sources in distant galaxies
Object: Cepheids…
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E. photometry of suddenly bright sources in distant galaxies
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Matching objects observed to the techniques used to measure distances in the Universe.
A. radar
B. astrometry to measure trigonometric parallax
C. light curves of variable stars
D. Hubble's Law
E. photometry of suddenly bright sources in distant galaxies
Object: supernov…
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A. rada
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Matching objects observed to the techniques used to measure distances in the Universe.
A. radar
B. astrometry to measure trigonometric parallax
C. light curves of variable stars
D. Hubble's Law
E. photometry of suddenly bright sources in distant galaxies
Object: Venus
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B. astrometry to measure trigonometric parallax
|
Matching objects observed to the techniques used to measure distances in the Universe.
A. radar
B. astrometry to measure trigonometric parallax
C. light curves of variable stars
D. Hubble's Law
E. photometry of suddenly bright sources in distant galaxies
Object: a red dw…
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D. Hubble's Law
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Matching objects observed to the techniques used to measure distances in the Universe.
A. radar
B. astrometry to measure trigonometric parallax
C. light curves of variable stars
D. Hubble's Law
E. photometry of suddenly bright sources in distant galaxies
Object: quasars
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B. Stelliferous Era
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Matching the energy source to the Era in which it is important.
A. Primordial Era
B. Stelliferous Era
C. Degenerate Era
D. Black Hole Era
E. Dark Era
Energy Source: proton-proton chain
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E. Dark Era
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Matching the energy source to the Era in which it is important.
A. Primordial Era
B. Stelliferous Era
C. Degenerate Era
D. Black Hole Era
E. Dark Era
Energy Source: electron/positron annihilation
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C. Degenerate Era
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Matching the energy source to the Era in which it is important.
A. Primordial Era
B. Stelliferous Era
C. Degenerate Era
D. Black Hole Era
E. Dark Era
Energy Source: proton decay
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A. Primordial Era
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Matching the energy source to the Era in which it is important.
A. Primordial Era
B. Stelliferous Era
C. Degenerate Era
D. Black Hole Era
E. Dark Era
Energy Source: Big Bang
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D. Black Hole Era
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Matching the energy source to the Era in which it is important.
A. Primordial Era
B. Stelliferous Era
C. Degenerate Era
D. Black Hole Era
E. Dark Era
Energy Source: Hawking radiation
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D. planetary nebula
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In which stage of a star's evolution is radiation pressure a clear winner over gravity?
A. contraction of protostar
B. pulsating variable star
C. collapse of core to ball of neutrons
D. planetary nebula
E. main sequence
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E. +10
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The Sun's absolute magnitude is about +5. If it were 100 pc away, what would it's apparent magnitude be?
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B. radius
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On the Hayashi track (during the protostar stage), a star radically changes its
A. age
B. radius
C. color
D. multiplicity
E. method of fuel burning
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C. carbon, nitrogen, and oxygen
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After hydrogen and helium, the most abundant elements in the Universe are
A. uranium, neptunium, and plutonium
B. argon, krypton, and xenon
C. carbon, nitrogen, and oxygen
D. gold, silver, and bronze
E. lithium, beryllium, and boron
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A. proton-proton chain
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The Sun burns hydrogen into helium primarily by the
A. proton-proton chain
B. s-process
C. triple alpha process
D. helium capture
E. CNO cycle
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Mewn faze!
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brrrdambum.
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1,000 times longer
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How long will a red dwarf last relative to our Sun, if the red dwarf has mass 0.1 Msun and luminosity 10-5 Lsun?
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C. s-process in massive stars
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The atoms making up the gold and silver in the jewelry in this room came from
A. proton-proton chain
B. r-process supernova
C. s-process in massive stars
D. white dwarf nova eruptions
E. helium capture
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D. gravity overwhelms neutron degeneracy pressure
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A core-collapse (Type II) supernova occurs when
A. the Sun climbs the asymptotic giant branch
B. helium flash occurs
C. two white dwarfs merge
D. gravity overwhelms neutron degeneracy pressure
E. a white dwarf goes over the Chandrasekhar mass
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E. spectroscopy
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To determine which molecules are forming in the cool outer layers of a red supergiant, which technique would you use?
A. astrometry
B. photometry
C. neutrinometry
D. polarimetry
E. spectroscopy
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E. age, mass
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Star clusters are superb places to study stellar evolution because the stars in them all have nearly identical ________, but different ________.
A. age, distance
B. mass, competition
C. age, composition
D. distance, age
E. age, mass
|
|
B. globular clusters
|
The oldest stars are found in
A. the Orion Nebular star formation complex
B. globular clusters
C. binary systems with one O-type star and one B-type star
D. the Pleiades
E. giant molecular clouds
|
|
6 years
|
The orbital period of a 6.6 Msun B star and a 3.4 Msun black hole separated by 7 AU is about....
|
|
A. 8 years
|
A binary star system has a total mass of 2 Msuns and the stars are separated by 5 AU. The time it will take for the stars to orbit one another is approximately:
A. 8 years
B. 125 years
C. 3 years
D. 5 years
E. 65 years
|
|
B. size
|
Which of the following CANNOT efficiently be learned about a dark dust cloud using spectroscopy?
A. temperature
B. size
C. density
D. velocity
E. composition
|
|
A. 10 billion years
|
What is the total length of time that our Sun burns hydrogen (include the time already burned)?
A. 10 billion years
B. 1 trillion years
C. 600 million years
D. 4.5 billion years
E. 1 billion years
|
|
A. Arcturus
|
Which of the stars in the research list take less than 100 years to move 1 arcminute across the sky?
A. Arcturus
B. Vega
C. Betelgeuse
D. Hadar
E. Aldebaran
|
|
B. Arcturus
|
Which of the stars on the research list moves the fastest across the sky?
A. Sirius
B. Arcturus
C. Pollux
D. Mimosa
E. Procyon
|
|
C. a giant molecular cloud
|
The most chemically complex substances are found in
A. the outer atmospheres of O-type stars
B. the Sun's core
C. a giant molecular cloud
D. a neutron star
E. the radiative zone of a G-type star
|
|
B. giant molecular cloud
|
The most dense component of dust and gas between the stars is a
A. hot superbubble
B. giant molecular cloud
C. general interstellar medium
D. emission nebula
E. supernova remnant
|
|
D. photometry
|
To measure the changing amount of light from a supernova explosion, which observing technique would you use?
A. astrometry
B. polarimetry
C. pixelometry
D. photometry
E. spectroscopy
|
|
D. photometry
|
To measure the changing amount of light from a pulsating variable star, which observing technique would you use?
A. astrometry
B. polarimetry
C. pixelometry
D. photometry
E. spectroscopy
|
|
0.25 arcseconds
|
A new black hole is found lurking at a distance of only 4 parsecs. What is its parallax?
|
|
D. 0.25 arcseconds
|
The resolution limit of a 2.2 meter (diameter) telescope at 2.2 microns is:
A. 4.00 arcseconds
B. 2.20 arcseconds
C. 1.00 arcseconds
D. 0.25 arcseconds
E. 0.10 arcseconds
|
|
D. Deneb
|
Which of the stars on the research list is currently producing the most energy?
A. Arcturus
B. Betelgeuse
C. Capella
D. Deneb
E. Sun
|
|
D. Deneb
|
Which of the stars in the research list is furthest away?
A. Pollux
B. Spica
C. Antares
D. Deneb
E. Altair
|
|
D. the Sun loses mass in the red giant phase
|
According to the current evolution models for the Sun, the Earth will NOT be engulfed by the Sun because
A. the Sun shrinks to a white dwarf before becoming a red giant
B. the Sun's pulsations will push the Earth outward
C. Venus slows down the expansion
D. the Sun loses mass …
|
|
C. nearby brown dwarf that expands into a red giant
|
Which is the LEAST likely trigger to star formation in a giant molecular cloud?
A. radiation and winds from O-type and B-type stars
B. nearby supernova explosion
C. nearby brown dwarf that expands into a red giant
D. Galactic spiral density waves
E. nearby pass of a second …
|
|
200,000
|
About how many astronomical units are there in one parsec?
|
|
E. hydrogen burning
|
Which phase of the Sun's life lasts the longest amount of time?
A. helium burning
B. brown dwarf
C. carbon burning
D. supernova explosion
E. hydrogen burning
|
|
E. x-ray
|
Accretion disks around neutron stars and black holes would best be observed at which wavelength?
A. infrared
B. ultraviolet
C. visible
D. radio
E. x-ray
|
|
D. x-ray
|
Which photon has the most energy?
A. orange visible
B. ultraviolet
C. green visible
D. x-ray
E. infared
|
|
1200 km2
|
A neutron star is about 20 kilometers in diameter. About what is its surface area?
|
|
A. black dwarf
|
Which of the following has never been observed?
A. black dwarf
B. protostar
C. pulsar
D. red giant
E. blue-white supergiant
|
|
A. horizontal branch
|
In which state of its life is the Sun fusing helium into carbon?
A. horizontal branch
B. planetary nebula
C. main sequence
D. subgiant
E. white dwarf
|
|
C. 1/64
|
Wimpystar is an M-type dwarf with a radius of 0.5 Rsun and a temperature of 2900 K. Knowing that the temperature of the Sun is 5800 K, what is the luminosity of Wimpystar compared to the Sun?
|
|
A. usefulness as stellar laboratories
|
Which of the following is the same when considering both open clusters and globular clusters?
A. usefulness as stellar laboratories
B. number of stars
C. age
D. most massive star observed
E. amount of "metals" in stars
|
|
A. neutrinos from a supernova
|
Which of the following CANNOT be measured using the Doppler effect?
A. neutrinos from a supernova
B. expansion of a planetary nebula
C. orbital velocities of a white dwarf/red dwarf pair
D. pulsations of the layers of a red giant
E. motion of jet of material in O star/black…
|
|
C. infrared
|
Which wavelength photons would be best for observing a T Tauri star?
A. x-ray
B. ultraviolet
C. infrared
D. visible
E. cosmic ray
|
|
B. number of stars involved
|
The fundamental difference between Type I and Type II supernovae is the
A. luminosity of supernovae
B. number of stars involved
C. duration of supernova event
D. number of neutrinos produced
E. rate at which they occur in the Milky Way
|
|
B. Procyon B
|
Which of the stars on the research list has ended its main sequence life?
A. Spica B
B. Procyon B
C. Aldebaran B
D. Capella B
E. Antares B
|
|
D. Procyon
|
Which of the stars on the research list is nearest to Earth?
A. Spica
B. Capella
C. Hadar
D. Procyon
E. Deneb
|
|
A. nearby hot stars emitting photons
|
Emission nebulae are in emission because of
A. nearby hot stars emitting photons
B. infrared photons from hundreds of small stars
C. they are "burning" like a forest fire
D. strong magnetic fields
E. they are full of black holes
|
|
B. Radio
|
Which photon has the longest wavelength?
A. blue visible
B. radio
C. ultraviolet
D. x-ray
E. red visible
|
|
D. Infared
|
Which type of telescope would you primarily use to observe cool stars?
A. gamma ray
B. x-ray
C. visible
D. infared
E. radio
|
|
B. 50 square meters [Area=piR^2=3x(4m)^2=3x16square meters=50 square meters)
|
The collecting area of an 8 meter diameter telescope is about:
A. 200 square meters
B. 50 square meters
C. 25 square meters
D. 16 square meters
E. 8 square meters
|
|
C. gamma rays from a neurtron star's accretion disk
|
Which of the following could NOT be detected using a telescope on the Earth's surface?
A. cool stars with temperatures of 3000 K
B. reflected visible light from Jupiter's moon Europa
C. gamma rays from a neutron star's accretion disk
D. infared radiation from the surface of Ti…
|
|
D. 16 minutes
|
Fifty years from now, you are on Mars and call a friend on Earth, 2 AU away. About how long does it take for your photons to reach Earth?
A. 60 minutes
B. 3 X 10^8 seconds
C. 1 second
D. 16 minutes
E. 5 hours
|
|
A. Chile
|
Many of the largest telecopes in the world are found in which southern hemisphere location?
A. Chile
B. Brazil
C. South Africa
D. China
E. Argentina
|
|
A. warm
|
Which of the following attributes is NOT good for a telescope location?
A. warm
B. high
C. dry
D. dark
E. stable atmosphere
|
|
E. Canopus
|
Which of the stars on the research list is brightest as seen from Earth?
A. Altair
B. Betelgeuse
C. Deneb
D. Rigel
E. Canopus
|
|
B. luminosity and temperature
|
The two axes on the HR diagram are:
A. chemical reaction and time
B. luminosity and temperature
C. gravity and radiation pressure
D. color and radius
E. mass and density
|
|
C. parallaxes
|
Astrometry can be used to measure:
A. radial velocities
B. composition of a star's atmosphere
C. parallaxes
D. dimming of a star because of an eclipse
E. changing colors in Sun's surface
|
|
A. sunspots
|
Which is NOT produced during the proton-proton chain in the Sun?
A. sunspots
B. neutrinos
C. energy
D. gamma ray photons
E. helium atoms
|
|
A. +25
|
A brown dwarf lurks only 1 pc away from the Sun. It has an absolute magnitude of +30. Its apparent magnitude is:
A. +25
B. -10
C. -5
D. +30
E. -15
|
|
A. half a million years
|
Gongahugestar has a mass of 30 times that of the Sun and is 600,000 times more luminous than the Sun. If the Sun will live 10,000,000,000 years, how long will Gongahugestar live?
A. half a million years
B. 1 x 10^10 years
C. 17000 years
D. 1.8 x 10^7 years
E. 1/20000 years
|
|
A. 1800 arcseconds
|
What is the size of the full Moon in the sky?
A. 1800 arcseconds
B. 10 arcseconds/year
C. 6378 km
D. 2 degrees
E. 60 arcminutes
|
|
E. there are islands of condensed iron floating on the surface
|
Sunspots are observed on the Sun for all the following reasons EXCEPT:
A. it rotates at different rates at the equator and poles
B. there are cooler regions in its photosphere
C. magnetic field lines get twisted
D. it has a convective zone
E. there are islands of condensed …
|
|
A. surface temperature
|
A blackbody spectrum can be used to directly measure what for a star?
A. surface temperature
B. diameter
C. mass
D. lumosity
E. convective cell size
|
|
B. spectroscopy (looking for red/blue shift--Doppler effect)
|
Which do you use to measure the velocity of a stay moving directly towards or away from you?
A. photometry
B. spectroscopy
C. bathometry
D. polarimetry
E. astrometry
|
|
E. 1 micron
|
Wimpystar is an M-type dwarf with a radius of 0.1 Rsun and a temperature of 2900 K. What is its peak wavelength emission?
A. 2 Angstroms
B. 5.8 nanometers
C. 2900 microns
D. 1450 Angstroms
E. 1 micron
|
|
B. large
|
Cool stars can be very luminous if they are very:
A. hot
B. large
C. small
D. variable
E. red
|
|
B. radiative zone
|
Which can you NOT see directly when ovserving the Sun?
A. photons
B. radiative zone
C. granules
D. sunspots
E. prominences
|
|
E. radiative zone
|
The lowest temperature region of the Sun is the:
A. core
B. convective zone
C. chromosphere
D. corona
E. radiative zone
|
|
C. a proton will turn into an electron
|
When a photon is absorbed by a hydrogen atom, which of the following CANNOT occur?
A. an ion might be formed
B. the electron might move up one level
C. the proton will turn into an electron
D. an absorption line might be seen
E. electron might leave the atom
|
|
A. O3 (ozone)
|
The molecule responsible for blocking a large amount of ultraviolet photons from the Sun is:
A. O3 (ozone)
B. CO (carbon monoxide)
C. O2 (molecular oxygen)
D. H2O
E. chlorofluorocarbons (CFCs)
|
|
E. 8 parsecs
|
A star's parallax is 0.125 arcseconds, its distance is:
A. 25 parsecs
B. 10 parsecs
C. 4 parsecs
D. 12.5 parsecs
E. 8 parsecs
|
|
B. emission
|
Which type of spectrum will show you specific bright lines?
A. continuous
B. emission
C. absorption
D. blackbody
E. x-ray
|
|
E. decrease
|
If a star increases in size, while maintaining the same luminosity, what will happen to its temperature?
A. temperature is not related to size
B. stars can't change size
C. stay the same
D. increase
E. decrease
|
|
D. are on the main sequence
|
Most of the nearest stars:
A. are white dwarfs
B. have spectral type F
C. are larger than the Sun
D. are on the main sequence
E. have hone supernovae
|
|
E. hydrogen features
|
The sequence of stellar spectral types we use today initially relied on what kind of observed spectral features?
A. carbon, nitrogen, and oxygen features
B. water absorption features
C. blackbody curve
D. iron features
E. hydrogen features
|
|
C. white dwarfs
|
Small, hot, but not intrinsically bright, stars on the HR diagram are called:
A. brown dwarfs
B. F5 III stars
C. white dwarfs
D. red supergiants
E. O8 V stars
|
|
A. core
|
The highest temperature region of the Sun is the:
A. core
B. convection zone
C. chromosphere
D. corona
E. radiative zone
|
|
B. they don't convert hydrogen to helium in their cores
|
Which is FALSE about M dwarf stars?
A. they contribute more mass to the Galaxy than any other spectral type star
B. they don't convert hydrogen to helium in their cores
C. they are the most common type of star in the Universe
D. they have the lowest masses of all stars
E. t…
|
|
A. 100:1
|
The ration of the Sun's diameter to the Earth's diameter is about:
A. 100:1
B. 10:1
C. 1000:1
D. 10000:1
E. 2:1
|
|
E. H2O
|
Which of the following gases has the most significants greenhouse effect on planet Earth?
A. N2
B. CO2
C. chlorofluorocarbons (CFCs)
D. O2
E. H2O
|
|
D. increases by a factor of 25
|
Your spaceship is 5 AU from the star Alpha Centauri A. You fly in u ntil you are only 1 AU from the star. By how much does the gravitational force change on your ship?
A. does not change
D. increases by a factor of 5
C. decreases by a factor of 5
D. increases by a factor of 25…
|
|
E. 64 times more luminous
|
Impressivostar is twice as hot as the Sun and twice the radius. How much more luminous is it than the Sun?
A. 4 times more luminous
B. 8 times more luminous
C. 16 times more luminous
D. 32 times more luminous
E. 64 times more luminous
|
|
B. cornea
|
Which part of your visual system is like the focusing elements in a telescope?
A. pupil
B. cornea
C. optic nerve
D. retina
E. computer
|
ASTR 1020: STUDY GUIDE