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

Need help with your exam preparation?

Question #1
Typical novae occur when
A.   matter accreted from a companion star unstably ignites on the surface of a white dwarf
B.   two neutron stars merge, forming a more massive neutron star.
C.   a neutron star's magnetic field becomes strong enough to produce two oppositely directed jets of rapidly moving particles.
D.   a red-giant star ejects a planetary nebula.
E.   an extremely massive star collapses, and also ejects its outer atmosphere.
Question #2
After the red supergiant phase, if the stellar core retains four solar masses, the result would be a:
A.   black hole
B.   neutron star
C.   white dwarf
D.   supernova
Question #3
Which one of the following statements about our Milky Way Galaxy is false?
A.   New stars generally form in the spiral arms.
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.   Globular star clusters reside in the halo and contain main-sequence stars spanning all spectral types, from O through M.
E.   Nebulae such as the Orion Nebula are stellar nurseries - regions where new stars are forming, or recently formed.
Question #4
High-redshift arcs around clusters of galaxies at low redshifts are now thought to be examples of gravitational lensing.
A.   TRUE
B.   FALSE
Question #5
White dwarf stars
A.   are the end states only of stars whose initial mass if much greater than that of the Sun.
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.   consist largely of carbon and oxygen.
E.   shine only while nuclear reactions continue within them.
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.   dark energy
B.   stars, protons, neutrons, electrons
C.   none of these
D.   dark matter
Question #7
The 21-cm line observed by radio astronomers comes from
A.   dust grains in molecular clouds.
B.   the atomic hydrogen spin-flip transition.
C.   carbon monoxide (CO) molecules.
D.   electrons in hydrogen atoms jumping from the third to the second energy levels.
E.   the rotation of hydrogen 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.   irregular
B.   dwarf
C.   lenticular
D.   spiral
E.   elliptical
Question #9
How would we recognize the presence of a black hole?
A.   Identify an accretion disk emitting x-rays.
B.   All of these answers would work.
C.   Find an astrometric binary with a massive companion.
D.   Find star(s) orbiting a blank spot.
Question #10
A dark nebula reflects light from stars that are near the gas.
A.   FALSE
B.   TRUE
Question #11
What would be found on the Main Sequence?
A.   red supergiants
B.   super massive black holes
C.   Cepheid variables
D.   white dwarfs
E.   sun-like stars
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.   a Blue Supergiant
B.   dust and gas
C.   one black hole
D.   a captured galaxy
Question #13
Which pair of scientific notation match 560,000,000 0.12
A.   5.6 x 108 1.2 x 10-1
B.   5.6 x 107 1.2 x 101
C.   5.6 x 108 1.2 x 101
D.   5.6 x 107 1.2 x 10-1
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 contracts and thus heats up.
B.   the core expands and thus heats up.
C.   the core expands and thus cools down.
D.   the core contracts and thus cools down.
E.   the core remains about the same size, but heats up as fusion of helium to carbon begins immediately after the hydrogen fuel is gone.
Question #16
At the present time, stars in our Galaxy tend to be most readily formed in
A.   the Galactic bulge.
B.   globular star clusters.
C.   the Galactic halo.
D.   the central supermassive black hole.
E.   giant molecular clouds in spiral arms.
Question #17
Which statement regarding deuterium is false?
A.   It has one electron, so it is not an ion.
B.   It is an isotope of hydrogen.
C.   It has one neutron and one proton.
D.   It has one more proton than an average hydrogen atom.
Question #18
Clouds of ionized hydrogen are called emission nebulae or
A.   HIII regions
B.   Type Ia regions
C.   HII regions
D.   HI 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.   Clouds of gas and dust are mostly found in spiral arms.
C.   Spiral arms consist mostly of dark matter.
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.   TRUE
B.   FALSE
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.   4
B.   1/16
C.   16
D.   1/4
E.   1
Question #22
Where does the hydrogen fuel come from to cause a white dwarf to nova or supernova?
A.   neighboring giant
B.   supernovae
C.   outer shells of gas
D.   nearby main sequence cluster stars
E.   passing nebulae (cocoon)
Question #23
Which kind of galaxies are compact, have only visible red dwarfs, have little dust & gas but no disk or arms?
A.   lenticular
B.   irregular
C.   spiral
D.   elliptical
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.   FALSE
B.   TRUE
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 can be used to determine the lookback times of distant galaxies - that is, how far back in time we are seeing them.
C.   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.
D.   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.
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.   Venus
B.   Io
C.   Uranus
D.   Triton
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.   gravitational funnel
B.   center of mass
C.   Roche Limit
D.   Roche Lobe
Question #31
Which one of the following statements about galaxy evolution is false?
A.   Most elliptical galaxies formed within the first few billion years after the big bang.
B.   Our Milky Way Galaxy and the Andromeda Galaxy are likely to form an elliptical galaxy at some time in the future.
C.   In the past, there existed a population of small, blue, irregular galaxies that have either merged together or faded from view.
D.   At least some galaxies formed from the joining together (merging) of small groups of stars.
E.   Astronomers can learn about the evolution of galaxies with images of the same galaxies taken by Edwin Hubble in the early 20th century.
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.   Each cluster of galaxies is the same size.
B.   Super-clusters expand outward from a Big Bang source.
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.   11,700,000 light years
B.   117,000,000 years
C.   11,700,000 years
D.   1,170,000 years
Question #34
At mid-northern latitudes (California), the full moon passes higher in the sky in winter than in summer.
A.   FALSE
B.   TRUE
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.   FALSE
B.   TRUE
Question #36
Hubble's Law implies that:
A.   collapsing very slowly.
B.   the Universe is expanding in a exponential fashion, accelerating faster and faster.
C.   the Universe is expanding in a linear fashion with constant speed.
D.   maintaining the same size.
Question #37
The presence of a black hole in a galatic core can be inferred from:
A.   the total mass of the galaxy.
B.   the speeds of the stars near the core.
C.   the diminished brightness of starlight in the galaxy core, relative to surrounding areas.
D.   the distance of the galaxy from the Milky Way Galaxy.
E.   the color of the galaxy.
Question #38
Which planet's orbit is elliptical enough that the seasons are not equal in length?
A.   Venus
B.   Earth
C.   Uranus
D.   Mars
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.   TRUE
B.   FALSE
Question #40
Match something in its possible evolutionary line with its progenitor: Red giant
A.   Supergiant
B.   the collision of two neutron stars or two black holes
C.   Sun-like star
D.   Binary system with a white dwarf
Question #41
  
A.   Binary system with a white dwarf
B.   Sun-like star
C.   Supergiant
D.   the collision of two neutron stars or two black holes
Question #42
Match something in its possible evolutionary line with its progenitor: Type Ia Supernova
A.   Binary system with a white dwarf
B.   Supergiant
C.   Sun-like star
D.   the collision of two neutron stars or two black holes
Question #43
Match something in its possible evolutionary line with its progenitor: gravitational waves
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 #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.   Supergiant
B.   Sun-like star
C.   Binary system with a white dwarf
D.   the collision of two neutron stars or two black holes
Question #46
Match something in its possible evolutionary line with its progenitor: Supernova remnant
A.   Sun-like star
B.   Supergiant
C.   the collision of two neutron stars or two black holes
D.   Binary system with a white dwarf
Question #47
Where in our galaxy is there enough dust and gas to make new stars?
A.   dark matter halo
B.   spiral arms
C.   nuclear bulge
D.   stellar halo
Question #48
In what kind of nebula would we find ionized gas sending out its own light?
A.   emission
B.   reflection
C.   dust
D.   absorption
Question #49
Galaxies move about the center of mass of their supercluster, sometimes merging due to:
A.   gas & dust
B.   ignition
C.   supernova explosions
D.   gravity
Question #50
Inside a red supergiant, denser elements fuse and emit sufficient energy to balance thermal expansion versus gravity, until ________________ is produced.
A.   helium
B.   carbon & oxygen
C.   iron
D.   silica & sulphur
E.   deuterium & tritium
Question #51
What is a planetary nebula?
A.   a planet atmosphere
B.   an exploding white dwarf
C.   an expelled shell of gas
D.   a small black hole

Need help with your exam preparation?