SMT 314 - Introduction to Cosmology » Fall 2020 » Exam 4

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Question #1
Typical novae occur when
A.   two neutron stars merge, forming a more massive neutron star.
B.   a neutron star's magnetic field becomes strong enough to produce two oppositely directed jets of rapidly moving particles.
C.   a red-giant star ejects a planetary nebula.
D.   an extremely massive star collapses, and also ejects its outer atmosphere.
E.   matter accreted from a companion star unstably ignites on the surface of a white dwarf
Question #2
After the red supergiant phase, if the stellar core retains four solar masses, the result would be a:
A.   white dwarf
B.   neutron star
C.   black hole
D.   supernova
Question #3
Which one of the following statements about our Milky Way Galaxy is false?
A.   Globular star clusters reside in the halo and contain main-sequence stars spanning all spectral types, from O through M.
B.   It is difficult to see the central regions of our Galaxy in optical (visible) light because intervening dust absorbs and scatters light.
C.   Rapid motions of stars near the center suggest that it harbors a black hole, millions of times the mass of our Sun.
D.   Nebulae such as the Orion Nebula are stellar nurseries - regions where new stars are forming, or recently formed.
E.   New stars generally form in the spiral arms.
Question #4
High-redshift arcs around clusters of galaxies at low redshifts are now thought to be examples of gravitational lensing.
A.   FALSE
B.   TRUE
Question #5
White dwarf stars
A.   consist largely of carbon and oxygen.
B.   consist largely of uranium and other very heavy elements.
C.   support themselves against the pull of gravity in the same way as normal stars link the Sun, using the pressure exerted by hot gases within them.
D.   shine only while nuclear reactions continue within them.
E.   are the end states only of stars whose initial mass if much greater than that of the Sun.
Question #6
Planetary orbits about the Sun have slower orbital speed far from the Sun. The rotation curve of our galaxy suggests that orbital speed is constant along the spiral arms. To understand the role of gravity, it has been proposed that our Galaxy has mass at great distances from the galactic center. What does the text identify makes up most of that mass?
A.   stars, protons, neutrons, electrons
B.   dark energy
C.   dark matter
D.   none of these
Question #7
The 21-cm line observed by radio astronomers comes from
A.   the atomic hydrogen spin-flip transition.
B.   electrons in hydrogen atoms jumping from the third to the second energy levels.
C.   the rotation of hydrogen molecules.
D.   dust grains in molecular clouds.
E.   carbon monoxide (CO) molecules.
Question #8
Which kind of galaxies are compact, have only visible red dwarfs, have little dust & gas but are disk-shaped without arms?
A.   dwarf
B.   lenticular
C.   irregular
D.   elliptical
E.   spiral
Question #9
How would we recognize the presence of a black hole?
A.   All of these answers would work.
B.   Find an astrometric binary with a massive companion.
C.   Identify an accretion disk emitting x-rays.
D.   Find star(s) orbiting a blank spot.
Question #10
A dark nebula reflects light from stars that are near the gas.
A.   TRUE
B.   FALSE
Question #11
What would be found on the Main Sequence?
A.   Cepheid variables
B.   red supergiants
C.   sun-like stars
D.   white dwarfs
E.   super massive black holes
Question #12
Out of about 1012 solar masses in the Milky Way, 4 million solar masses are found in the center in what object?
A.   dust and gas
B.   one black hole
C.   a captured galaxy
D.   a Blue Supergiant
Question #13
Which pair of scientific notation match 560,000,000 0.12
A.   5.6 x 107 1.2 x 10-1
B.   5.6 x 108 1.2 x 10-1
C.   5.6 x 108 1.2 x 101
D.   5.6 x 107 1.2 x 101
Question #14
By using the method of gravitational lensing, we can measure the total mass (light matter + dark matter) of the lensing object.
A.   TRUE
B.   FALSE
Question #15
When a main-sequence star runs out of hydrogen fuel in its core,
A.   the core expands and thus cools down.
B.   the core contracts and thus cools down.
C.   the core contracts and thus heats up.
D.   the core remains about the same size, but heats up as fusion of helium to carbon begins immediately after the hydrogen fuel is gone.
E.   the core expands and thus heats up.
Question #16
At the present time, stars in our Galaxy tend to be most readily formed in
A.   the Galactic halo.
B.   the Galactic bulge.
C.   globular star clusters.
D.   giant molecular clouds in spiral arms.
E.   the central supermassive black hole.
Question #17
Which statement regarding deuterium is false?
A.   It has one neutron and one proton.
B.   It has one electron, so it is not an ion.
C.   It has one more proton than an average hydrogen atom.
D.   It is an isotope of hydrogen.
Question #18
Clouds of ionized hydrogen are called emission nebulae or
A.   HI regions
B.   HII regions
C.   HIII regions
D.   Type Ia regions
Question #19
Spiral arms are usually the most prominent features in the disk of a spiral galaxy. Which one of the statements about spiral arms is false?
A.   Spiral arms contain most of the hot, young, massive stars.
B.   Spiral arms consist mostly of dark matter.
C.   Clouds of gas and dust are mostly found in spiral arms.
D.   Spiral arms are usually the most prominent features in the disk.
E.   Emission nebulae are mostly found in spiral arms.
Question #20
Distant galaxies have small lookback times, allowing us to study the evolution of galaxies.
A.   FALSE
B.   TRUE
Question #21
Inverse square law: If Stars Fred and Ernie have the same apparent brightness, but Star Fred is 4 times farther away from Earth than Star Ernie, then Star Ernie's luminosity (absolute magnitude) is _________ times the luminosity of Star Fred. o Earth * Ernie * Fred
A.   1/4
B.   1
C.   1/16
D.   16
E.   4
Question #22
Where does the hydrogen fuel come from to cause a white dwarf to nova or supernova?
A.   outer shells of gas
B.   nearby main sequence cluster stars
C.   supernovae
D.   passing nebulae (cocoon)
E.   neighboring giant
Question #23
Which kind of galaxies are compact, have only visible red dwarfs, have little dust & gas but no disk or arms?
A.   elliptical
B.   spiral
C.   irregular
D.   lenticular
E.   dwarf
Question #24
The retrograde motion of Pluto can be attributed to the relatively high eccentricity of its orbit around the Sun, as compared normal planets.
A.   TRUE
B.   FALSE
Question #25
Which one of the following statements about the expanding Universe and Hubble's law (v = Hod) is false?
A.   Despite the expansion of the Universe, pairs of galaxies can still sometimes move toward each other and even merge together.
B.   Hubble's law alone implies that as the distance of a particular galaxy increases with time, it moves away from us progressively faster; in other words, it's accelerating away from us.
C.   If Galaxies Luke and Yoda both satisfy Hubble's law, and Galaxy Luke's distance is three times Galaxy Yoda's distance, then Galaxy Luke is moving away from us three times faster than Galaxy Yoda.
D.   Hubble's law can be used to determine the lookback times of distant galaxies - that is, how far back in time we are seeing them.
Question #26
A white dwarf in a binary star system can undergo nuclear reactions on its surface, producing a nova but not destoying the entire star.
A.   FALSE
B.   TRUE
Question #27
Which celestial body has a retrograde rotation?
A.   Triton
B.   Io
C.   Venus
D.   Uranus
Question #28
Spiral galaxies contain only relatively young stars; there are no ancient stars anywhere within them.
A.   FALSE
B.   TRUE
Question #29
The chemical composition of a black hole can be determined from measurements conducted outside the black hole.
A.   FALSE
B.   TRUE
Question #30
Mass exchange from one star to the other can occur if one star extends into the ________________ of its companion.
A.   center of mass
B.   gravitational funnel
C.   Roche Limit
D.   Roche Lobe
Question #31
Which one of the following statements about galaxy evolution is false?
A.   At least some galaxies formed from the joining together (merging) of small groups of stars.
B.   Astronomers can learn about the evolution of galaxies with images of the same galaxies taken by Edwin Hubble in the early 20th century.
C.   Most elliptical galaxies formed within the first few billion years after the big bang.
D.   In the past, there existed a population of small, blue, irregular galaxies that have either merged together or faded from view.
E.   Our Milky Way Galaxy and the Andromeda Galaxy are likely to form an elliptical galaxy at some time in the future.
Question #32
Structure of the Universe: 2dF and the Sloan Microwave Digital Survey plotted clusters of galaxies. What kind of structure was seen among super-clusters of galaxies?
A.   Super-clusters expand outward from a Big Bang source.
B.   Each cluster of galaxies is the same size.
C.   Filaments of galaxies surround voids that have no or very few galaxies inside.
D.   Super-clusters are uniform & homogeneous across the universe.
Question #33
The Sculptor Galaxy is spiral galaxy of Hubble type Sc, located within the Local Group. It is located 11.7 million light years from us. What is its lookback time? Please write out the whole number (long hand with zeros and commas) and the correct units.
A.   1,170,000 years
B.   11,700,000 light years
C.   117,000,000 years
D.   11,700,000 years
Question #34
At mid-northern latitudes (California), the full moon passes higher in the sky in winter than in summer.
A.   TRUE
B.   FALSE
Question #35
A red giant forms a planetary nebula when its outer atmosphere becomes unstable, producing a gentle ejection of hydrogen and helium, while leaving a neutron star.
A.   TRUE
B.   FALSE
Question #36
Hubble's Law implies that:
A.   maintaining the same size.
B.   the Universe is expanding in a exponential fashion, accelerating faster and faster.
C.   collapsing very slowly.
D.   the Universe is expanding in a linear fashion with constant speed.
Question #37
The presence of a black hole in a galatic core can be inferred from:
A.   the color of the galaxy.
B.   the diminished brightness of starlight in the galaxy core, relative to surrounding areas.
C.   the speeds of the stars near the core.
D.   the total mass of the galaxy.
E.   the distance of the galaxy from the Milky Way Galaxy.
Question #38
Which planet's orbit is elliptical enough that the seasons are not equal in length?
A.   Mars
B.   Venus
C.   Earth
D.   Uranus
Question #39
An emission nebula can form when gas is ionized by a nearby young star, often of spectral type G, K, or M.
A.   FALSE
B.   TRUE
Question #40
Match something in its possible evolutionary line with its progenitor: Red giant
A.   Supergiant
B.   Binary system with a white dwarf
C.   Sun-like star
D.   the collision of two neutron stars or two black holes
Question #41
  
A.   Binary system with a white dwarf
B.   the collision of two neutron stars or two black holes
C.   Supergiant
D.   Sun-like star
Question #42
Match something in its possible evolutionary line with its progenitor: Type Ia Supernova
A.   the collision of two neutron stars or two black holes
B.   Sun-like star
C.   Supergiant
D.   Binary system with a white dwarf
Question #43
Match something in its possible evolutionary line with its progenitor: gravitational waves
A.   Binary system with a white dwarf
B.   the collision of two neutron stars or two black holes
C.   Sun-like star
D.   Supergiant
Question #44
Match something in its possible evolutionary line with its progenitor: Nova
A.   Sun-like star
B.   Supergiant
C.   Binary system with a white dwarf
D.   the collision of two neutron stars or two black holes
Question #45
Match something in its possible evolutionary line with its progenitor: White dwarf and planetary nebula
A.   Binary system with a white dwarf
B.   Sun-like star
C.   the collision of two neutron stars or two black holes
D.   Supergiant
Question #46
Match something in its possible evolutionary line with its progenitor: Supernova remnant
A.   Binary system with a white dwarf
B.   the collision of two neutron stars or two black holes
C.   Sun-like star
D.   Supergiant
Question #47
Where in our galaxy is there enough dust and gas to make new stars?
A.   stellar halo
B.   spiral arms
C.   nuclear bulge
D.   dark matter halo
Question #48
In what kind of nebula would we find ionized gas sending out its own light?
A.   absorption
B.   dust
C.   emission
D.   reflection
Question #49
Galaxies move about the center of mass of their supercluster, sometimes merging due to:
A.   ignition
B.   gas & dust
C.   gravity
D.   supernova explosions
Question #50
Inside a red supergiant, denser elements fuse and emit sufficient energy to balance thermal expansion versus gravity, until ________________ is produced.
A.   deuterium & tritium
B.   carbon & oxygen
C.   iron
D.   silica & sulphur
E.   helium
Question #51
What is a planetary nebula?
A.   an expelled shell of gas
B.   a small black hole
C.   a planet atmosphere
D.   an exploding white dwarf

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