These are some questions over the material we have covered since the last test. In addition to these questions, you should review the end of chapter review questions.
PRS Questions
What fraction of the stars on an H-R diagram are on the main sequence.
Enter numbers 1-9 for 10%-90% (90%)
Stars A and B formed at the same time. Star B has 3 times the mass of star A. Star A has an expected lifetime of 3 billion years. What is the expected lifetime of star B?
A) more than 9 billion years
B) about 9 billion years
C) 3 billion years
D) about 1 billion years
E) less than 1 billion years
How would the luminosity of a one-solar-mass protostar compare to the sun?
A) Less than .1x as bright
B) A little lower.
C) About the same.
D) A little brighter
E) More than 10x brighter
How would the luminosity of a one-solar-mass protostar compare to the sun?
A) Less than .1x as bright
B) A little lower.
C) About the same.
D) A little brighter
E) More than 10x brighter
After hydrogen fusion stops in the core of a star, the core…
A) cools and the star as a whole expands
B) cools and the star as a whole contracts
C) heats and the star as a whole expands
D) heats and the star as a whole contracts
When a star becomes a red giant, it becomes much brighter because it is
A) moving closer to us
B) losing its outer envelope
C) fusing iron in its core
D) increasing in size
Where would be the best place to search for white dwarfs?
A) In the spiral arms of the Milky Way
B) In dense dust clouds
C) In globular clusters
D) In open clusters
Q. - After fusion stops in the core of a star, the core…
A) expands and heats
B) expands and cools
C) contracts and heats
D) contracts and cools
For a white dwarf to become a nova, it is necessary for it to
A) have a companion star
B) exceed its Chanrasekhar limit
C) have begun life as a high mass star
D) continue the fusion cycle until its core is completely composed of iron.
You observe two Cepheid variable stars. Star A has a period of 10 days. Star B has a period of 30 days. Which is more luminous?
A) A
B) B
C) they are the same
D) not enough information
You observe Cepheid
stars in two different galaxies (A and B). They have the same apparent
brightness.
Star in galaxy A has a period of 10 days. Star in galaxy B has a period of 30
days. Which galaxy is closer?
A) A
B) B
C) they are the same distance
D) not enough information
A star has an apparent magnitude of +1.0 and an absolute magnitude of +1.0. If the distance between Earth and the star increases, the apparent magnitude would _____, and the absolute magnitude would _____.
A) increase; decrease
B) decrease; increase
C) increase; not change
D) decrease; not change
E) not change; increase
Using spectroscopic parallax, you find a star’s distance to be 76 parsecs. You now find out that the star isn’t a main sequence star, but is a red giant. Your distance estimate is
A) too large
B) too small
C) fine - no significant change in estimate is needed.
A star has apparent magnitude of +8.0 before it goes nova and increases its luminosity by 10,000 times. Its apparent magnitude after it goes nova is.
A) +8.0
B) +18.0
C) -8.0
D) -2.0
E) +3.0
What method would be most appropriate to determine the distance to a nearby galaxy?
A) Spectroscopic parallax
B) Cepheid variables
C) Hubble’s law
D) Radar ranging
What method would not be appropriate to determine the distance to a nearby galaxy?
A) Tully-Fisher relationship
B) Cepheid variables
C) Hubble’s law
D) Type I Supernovae
Which of the following is inferred by Hubble’s Law?
A) The greater the distance, the more luminous the galaxy
B) The more distant a galaxy, the more evolved its members are
C) The larger the redshift, the more distant the galaxy
D) The larger the gravity lens, the more massive the galaxy cluster.
What does the Hubble constant measure?
A) The density of galaxies in the universe
B) The luminosity of distant galaxies
C) The rate of expansion of the universe
D) the speed of a galaxy of known redshift
E) the reddening of light by intergalactic dust clouds
Chapter
11
1) Why are star clusters ideal "laboratories" for stellar evolution?
A) Their stars are all the same composition and stage in evolution.
B) The combined light of all the stars makes them easier to see.
C) Their stars are all about the same mass and temperature.
D) Their stars are all about the same age, composition, and distance from us.
E) Like our Sun, they lie in the plane of the Milky Way.
2) What are the characteristics of an open cluster?
A) no stars left on the main sequence, but millions of white dwarfs
B) a few hundred stars, most still on the main sequence
C) millions of stars, both young and old, spread out over 100,000 ly.
D) a star forming region, hundreds of light years across, with many blue main sequence stars
E) old age and tens of thousands of stars
3) Which is characteristic of globular star clusters?
A) only brown dwarfs in a yellow ball 100 ly across
B) bright blue main sequence stars, and thousands of them
C) no remaining main sequence stars, but millions of white dwarfs
D) old age and hundreds of thousands of stars, only about 30 ly wide
E) a mix of old and young stars, about 100,000 ly across
4) The most common molecule in a molecular cloud is:
A) carbon monoxide, with one carbon and an oxygen.
B) ammonia, with three hydrogens attached to a nitrogen.
C) molecular hydrogen, made of two H atoms.
D) methane, with four hydrogens around a hydrogen.
E) water, with two hydrogens around an oxygen.
5) What effect does even thin clouds of dust have on light passing through them?
A) It dims and reddens the light of all more distant stars.
B) Even a little can completely block all light, such as the Horsehead Nebula.
C) Its motion causes all light to be red shifted as it passes through these clouds.
D) Its motion causes the light of stars beyond to twinkle.
E) The light that passes through them is blue shifted due to the cloud's approach.
6) Interstellar gas is composed mainly of:
A) only hydrogen.
B) some hydrogen, but mainly carbon dioxide.
C) 10% hydrogen, 90% helium by numbers of atoms.
D) 75% hydrogen, 25% helium by weight.
E) ammonia, methane, and water vapor.
7) Why are dark dust clouds largely misnamed?
A) The cloud is an illusion, for the dust is evenly distributed around the Galaxy.
B) It is ice, not dust, which make them look dark.
C) Dust clouds do radiate energy, but not as much light as the stars do.
D) They contain much more gas than dust.
E) All of the above are correct.
8) Complex molecules in the inter-stellar medium are found:
A) uniformly throughout the disk of the Galaxy.
B) only around the supergiant stars like Betelguese that make their heavy atoms.
C) on the surfaces of the coolest class K and M stars only.
D) scattered evenly throughout the universe, a product of the Big Bang itself.
E) primarily in the dense dust clouds.
9) A cloud fragment too small to collapse into a main sequence star becomes a:
A) pulsar.
B) brown dwarf.
C) white dwarf.
D) planet of another star.
E) T Tauri object.
10) How long does it take an M class star to reach the main sequence, compared to a solar type star?
A) a tenth as long
B) longer than the age of the Galaxy
C) about twice as long
D) about twenty times longer
E) about the same, 30 million years
D B D C A D D E B D
Chapter 12
1) The helium flash converts helium nuclei into
A) carbon
B) beryllium
C) oxygen
D) iron
E) boron
2) Which is used observationally to determine the age of a star cluster?
A) the number of white dwarfs
B) the total number of main sequence stars
C) the amount of dust that lies around the duster
D) the ratio of giants to supergiants
E) the luminosity of the main sequence turn-off point
3) In a white dwarf, we have packed the mass of the Sun into the volume of:
A) the Moon.
B) Jupiter.
C) Eros.
D) Earth.
E) Mars.
4) The brightest stars in a young open cluster will be:
A) red T-tauri stars still heading for the main sequence.
B) yellow giants like our Sun, but much larger.
C) the core stars of planetary nebulae.
D) massive blue stars at the top left on the H-R diagram.
E) red giants that are fusing helium into carbon.
5) A relatively peaceful mass loss as a giant core becomes a white dwarf is a:
A) emission nebula.
B) nova.
C) supernova remnant.
D) planetary nebula.
E) supernova.
6) What forces a star like our Sun to evolve off the main sequence?
A) It loses all its neutrinos, so fusion must cease.
B) It completely runs out of hydrogen.
C) It builds up a core of inert helium.
D) It explodes as a violent nova.
E) It expels a planetary nebula to cool off and release radiation.
7) A surface explosion when a companion spills hydrogen onto its close white dwarf companion creates a:
A) nova.
B) Type I supernova.
C) emission nebula.
D) Type II supernova.
E) planetary nebula.
8) For a white dwarf to explode entirely as a Type I supernova, it must weigh:
A) 20 solar masses, the Hubble Limit.
B) at least 8% as much as the Sun.
C) 1.4 solar masses, the Chandrasekhar Limit.
D) 3 solar masses, the Schwartzchild Limit.
E) 100 solar masses, the most massive known stars.
9) Of the elements in your body, the only one not formed in stars is:
A) aluminum.
B) carbon.
C) hydrogen.
D) iron.
E) calcium.
10) Which of these events is not possible?
A) close binary stars producing recurrent novae explosions
B) white dwarfs and companion stars producing recurrent Type I supernova events
C) red giants exploding as Type II supernovae
D) a white dwarf being found in the center of a planetary nebula
E) low-mass stars swelling up to produce planetary nebulae
A E D D D C A C C B
Chapter 13
A) asteroid
B) white dwarf
C) neutron star
D) brown dwarf
2) If the Sun were replaced by a one solar mass black hole:
A) we would immediately escape into deep space, driven out by its radiation.
B) our clocks would all stop.
C) life here would be unchanged.
D) we would still orbit it in a period of one year.
E) all terrestrial planets would fall in immediately.
3) The largest known black holes
A) create the dark nebulae in the plane of the Milky Way.
B) can be no more than 1.4 solar masses, according to Chandrasekhar.
C) lie in the cores of the most massive galaxies.
D) can be no bigger than a small city, just like neutron stars.
E) can be no bigger than the earth, like white dwarfs.
4) Which of these does not exist?
A) a six solar mass black hole
B) a million solar mass black hole
C) a 1.8 solar mass neutron star
D) a .06 solar mass brown dwarf
E) a 1.5 solar mass white dwarf
5) While perhaps affected by rotation and magnetism, we think the lower limit for black holes is:
A) Hubble's limit of 30 solar masses.
B) Shapley's limit of 75 solar masses.
C) Chandrasekhar's limit of 1.4 solar masses.
D) Einstein's limit of 8 solar masses for high-mass stars.
E) Schwartzschild's limit of 3 solar masses.
6) Neutron stars have:
A) very strong bi-polar magnetic fields.
B) weak or non-existent magnetic fields.
C) periods of days or weeks.
D) monopolar fields that switch polarity every rotation.
E) no relation to pulsars.
C D C E E A
Chapter 14
1) Which of these variable stars would be classified as a Cepheid?
A) a B supergiant with a period of .14 days
B) an M supergiant with a period of 140 days
C) a K giant with a period of 14 days
D) an F giant with a period of 14 years
E) a G giant with a period of 14 hours
2) In structure, our Milky Way is most often compared to:
A) the Large Magellanic Cloud.
B) an upscale version of a globular duster.
C) M-51, the Whirlpool Galaxy.
D) M-104, the sombrero Galaxy.
E) M-31, the Andromeda Galaxy.
3) The location of the Galactic Center was first found by Harlow Shapley with:
A) Cepheids of population I in the spiral arms.
B) RR Lyrae variables in the globular clusters.
C) planetary nebulae in the open dusters.
D) infrared observations of the heat from its accretion disk around the black hole.
E) radio emissions from Sagittarius A.
4) The period-luminosity relation is critical in finding distances with:
A) Cepheid variables.
B) RR Lyrae stars.
C) pulsars.
D) trigonometric parallaxes.
E) spectroscopic parallaxes.
5) What two observations allow us to calculate the Galaxy's mass?
A) the Sun's orbital velocity and its distance from the Galactic Center
B) the Sun's mass and velocity in orbit of the Galactic Center
C) the Sun's composition and luminosity
D) the Sun's age and period of the Galactic Year
E) the Sun's mass and its age
6) In the formation of our Galaxy, the _________ formed first.
A) planetary nebulae
B) galactic disk
C) spiral arms
D) galactic center
E) globular dusters
7) At the center of our Galaxy lies:
A) the largest of all globular dusters.
B) a black hole of millions of solar masses.
C) a quasar.
D) an intensely bright visible superstar.
E) a huge emission nebula.
8) What observations suggest the mass of the Galaxy goes much farther out than its visible disc?
A) the orbits of the open dusters in the disc
B) x-ray images of other galaxies' discs from Chandra
C) the rotation curve of the outermost portions of the disc
D) 21 cm maps of the spiral arms
E) infrared observations of distant brown dwarfs
9) Most of the mass of the Milky Way seems to exist in the form of:
A) population I stars in the disk.
B) population II stars in the Halo.
C) dark matter out in the Halo.
D) the black hole in the Galactic Center.
E) hydrogen gas in the disk and spiral arms.
10) Which of the following are most massive and luminous?
A) white dwarfs
B) Cepheid variables
C) RR Lyrae variables
D) T-Tauri variables
E) brown dwarfs
C E B A A E B C C B
Chapter
15
1) Which property is common to spiral galaxies?
A) globular clusters out in the halo
B) a disk, bulge, and halo
C) open clusters in the disk
D) on-going star formation and emission nebula in the arms
E) all of the above
2) What are Type I supernovae used for?
A) explaining the pulsars in supernova remnants
B) determining the half-lives of the heavy elements they create
C) standard candles for determining distances to other galaxies
D) calculating the density of the interstellar medium from their remnants
E) age-dating the massive stars in clusters where they blow up
3) The astronomer who originally classified galaxies into S, E, and Irr was:
A) William Herschel.
B) Harlow Shapley.
C) Edwin Hubble.
D) Carl Sagan.
E) Henrietta Leavitt.
4) For finding the distance to M-31, Hubble relied upon:
A) Type I supernova in its core.
B) Type II supernova in its spiral arms.
C) Cepheid variables in its spiral arms.
D) planetary nebulae near its core.
E) RR Lyrae stars in its globular clusters.
5) The Tully-Fisher Relation exists between the galaxy's luminosity and its:
A) color.
B) size.
C) mass.
D) age.
E) rotation.
6) Why does the Cepheid distance method fail us beyond about 20 Mpc?
A) The periods of Cepheids grows longer as the distances increase.
B) Distant galaxies are younger than our Milky Way; too young to have Cepheids yet.
C) Even with the HST, the most luminous Cepheids are too faint to be seen beyond.
D) Distant galaxies are seen in the past, and Cepheids evolve with time.
E) The intergalactic dust reddens the Cepheid's light and apparent brightness.
7) Why is the energy source for active nuclei like Seyferts thought to be compact?
A) We know the masses of the black holes that lurk there, and can find their radii.
B) The sources appear to be single stars in photos.
C) They are all strong radio sources, with assigned frequencies by their sizes.
D) Their energy appears to be non-stellar synchrotron radiation.
E) The light can vary over short time intervals, in just weeks.
8) Not only does the central engine of active galaxies and quasars require a black hole, but also to provide the radiate energy
A) a source of high-energy electrons for synchrotron radiation
B) globular clusters for food
C) a high rate of rotation for the black hole
D) a very strong magnetic field from neutron stars
E) an accretion disk of infalling matter
E C C C E C E E
Chapter 16
1) Which of the following is inferred by Hubble's Law?
A) The larger the red shift of the galaxy, the more distant it is.
B) The greater the distance, the more luminous the galaxy.
C) The larger the gravity lens, the more massive the galaxy cluster.
D) The greater the distance, the fainter the galaxy is in reality.
E) The more distant a galaxy, the more evolved its member stars will be.
2) What does the Hubble constant measure?
A) the speed of a galaxy of known red shift
B) the luminosity of distant galaxies
C) the reddening of light by intergalactic dust clouds
D) the density of galaxies in the universe
E) the rate of expansion of the universe
3) The Hubble constant's latest accepted value is:
A) 70 km/s/Mly.
B) 3x108 km/s.
C) 70 km/s/megaparsec.
D) 13.5 billion years.
E) 9.8m/s2.
4) According to Hubble's Law, if galaxy A shows us twice the red shift of galaxy B:
A) the galaxy A rotation is twice as fast, so the Tully-Fisher luminosity is twice as great as galaxy B.
B) galaxy A is half as distant as galaxy B.
C) the two galaxies are a binary system.
D) galaxy A must be twice as bright as galaxy B.
E) galaxy A is twice as far away as galaxy B.
5) Based on galactic rotation curves and cluster dynamics, we think dark matter:
A) is a minor component of the entire mass of the universe.
B) is best detected from the x-rays it produces in the intergalactic medium.
C) comprises over 90% of the entire mass of the universe.
D) will doom the universe to collapse, overcoming the red shifts we now observe.
E) will have no effect on the fate of the universe.
6) Which of these astronomers first related speeds and distances for galaxies?
A) Vesto M. Slipher
B) Henrietta Leavitt
C) Edwin Hubble
D) William Herschel
E) Harlow Shapley
7) Mapping the intergalactic gas is best done with:
A) the HST with hydrogen alpha light.
B) the Arecibo radio dish.
C) the Chandra X-ray Observatory in space.
D) the Keck telescope in the infrared.
E) the COBE satellite in microwaves.
8) After we can no longer spot Cepheids in the distance, we turn next to:
A) the period-luminosity relation.
B) the Stefan-Boltzman law.
C) the color of the brightest galaxies in the cluster.
D) the light curves of Type II supernovae.
E) the Tully-Fisher relation.
9) Red shift surveys give us:
A) an idea of how turbulent the intergalactic gas is.
B) the total mass of the universe.
C) a better value of the speed of light.
D) a 3-D layout of galaxies in space.
E) a more accurate census of the Local Group.
10) The huge sheet of galaxies that extends over 100 Mpc is the
A) The Virgo Supercluster
B) The Intergalactic Bubble.
C) The Great Wall
D) nothing but an optical illusion.
11) Using binary galaxies to find their masses assumes that their orbits:
A) obey the laws of Planetary Motion.
B) contain no dark matter.
C) are perfectly circular
D) are fast enough to show proper motion perpendicular to our line of sight.
A E C E C C C E D C A
Chapter 17
1) Because almost all galaxies show redshifted spectra, we know that
A) nobody likes us.
B) the sky must be dark at night.
C) we must be at the center of the universe.
D) the universe is expanding.
E) All of the above are correct.
2) The redshift of the galaxies is correctly interpreted as:
A) space itself is expanding with time, so the photons are stretched while they travel through space.
B) placing our Galaxy near the center of the Local Group.
C) the differences in temperatures and star formation in old and young galaxies.
D) a Doppler shift due to the random motions of galaxies in space.
E) an aging of light as gravity weakens with time.
3) What does the Hubble law imply about the history of the universe?
A) The red shifts will turn to blue shifts as universe contraction follows the expansion.
B) The universe must be infinitely old and huge.
C) The Milky Way lies exactly at the center of this expansion.
D) The red shifts will lengthen with time due to dark energy.
E) The universe started expanding in the past, and has a finite age and birth.
4) The concept that the direction of observation does not matter overall is:
A) geometry.
B) homogeneity.
C) universality.
D) isotropy.
E) relativity.
5) The concept that on the grandest of scales, the universe is similar in appearance everywhere is:
A) general relativity.
B) special relativity.
C) homogeneity.
D) isotropy.
E) universality.
6) The darkness of the night sky in an infinite universe is addressed in:
A) the Cosmological principle.
B) General Relativity.
C) Olbers' Paradox.
D) Steady State Physics.
E) Special Relativity.
D A E D C C