Astronomy Exam 3
20. The very strong source of radio waves at the center of our Galaxy is called a. Sagittarius A b. Cygnus X-1 c. the Crab Nebula d. Milky Way CC1 e. Benford G1
a. Sagittarius A
6. The central region of our Galaxy is not as flat as its main disk of stars. Which of the following has roughly the same shape as our central region of stars? a. a peanut b. a tennis ball c. a cube d. a long piece of string e. actually, no one knows the shape of our central region because of all the dust in the Galaxy
a. a peanut
30. The first, indirect detection of gravitational waves in the 1970s involved a. a pulsar that was in the same star system with a neutron star b. the black hole in the Cygnus X-1 system c. a star that was swelling up to be the largest red giant astronomers had ever seen d. a spacecraft that we purposely sent to fall into the strong gravity of the Sun e. the collapse of a huge garbage dump in the town of Bayonne, New Jersey
a. a pulsar that was in the same star system with a neutron star
11. From which of the following will a wave of light show the greatest gravitational redshift: a. a white dwarf b. a giant planet like Jupiter c. Earth d. the Sun e. a spaceship in empty space
a. a white dwarf
24. What type of main sequence star is most likely to become a black hole? a. an O-type star b. a G-type star c. a K-type star d. an M-type star e. you can't fool me, all spectral types on the main sequence have an equal chance of becoming black holes
a. an O-type star
23. The Tully-Fisher method for measuring the distance to galaxies relies on the observed relationship between the luminosity of a spiral galaxy and a. its rotational velocity (as determined from the width of the 21-cm line) b. its number of high-energy sources (as determined from the total gamma-ray emission) c. the size of its supernova remnants (as determined from radio maps) d. the number of globular clusters (as determined from high-resolution images) e. the number of companion galaxies found directly around it
a. its rotational velocity (as determined from the width of the 21-cm line)
13. To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at? a. mass b. surface temperature c. color d. distance e. diameter
a. mass
12. Radio astronomy has played a pivotal role in showing us the detailed structure of the Milky Way Galaxy. Which of the following techniques would a radio astronomer use as an essential part of an investigation of this structure? a. measuring the Doppler shift of a line in a radio spectrum b. taking a photograph of the sky in the direction of the Big Dipper c. using a CCD and a filter to record the amount of light from the stars in a nearby open cluster d. measuring the amount of synchrotron radiation from the Crab Nebula e. measuring the amount of radio radiation coming from the direction of Jupiter and other planets in the solar system
a. measuring the Doppler shift of a line in a radio spectrum
21. Wearing a very accurate watch, you volunteer to go on a mission to a black hole in a spaceship that has powerful rockets. You are able to orbit the black hole and stay a little distance outside of the event horizon. Compared to watches on Earth, your watch near the black hole will run: a. more slowly b. more quickly c. infinitely slow d. infinitely fast e. you can't fool me, watches near a black hole don't change the pace at which they run
a. more slowly
10. Our Milky Way Galaxy is what type of galaxy? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above
a. spiral
3. Our Milky Way Galaxy is what type of galaxy? a. spiral b. elliptical c. dwarf elliptical d. irregular e. giant elliptical
a. spiral
7. The type of galaxy that sometimes has a distinct bar of stars running across the central region is a. spiral b. elliptical c. dwarf elliptical d. irregular e. all of the above can have clear, distinct central bars
a. spiral
11. Among irregular galaxies, what makes the Large and Small Magellanic Cloud especially useful for astronomers? a. they are (for galaxies) very close to us, so they are easy to study b. they are among the biggest irregular galaxies ever found c. they have a regular shape, but it is so complicated it was hard to figure out d. they do not contain any young stars at all, only really old ones e. their shape resembles a map of Bayonne, New Jersey
a. they are (for galaxies) very close to us, so they are easy to study
20. Which of the following objects is considered useful to astronomers as a "standard bulb" for determining distances? a. type Ia supernovae b. planets that resemble Earth c. K-type stars d. the brightness of the bulge in a galaxy's center e. the size of the largest diameter open cluster in a galaxy
a. type Ia supernovae
2. The scientist who made the first telescopic survey of the Milky Way and discovered that it is composed of a huge number of individual stars was a. Isaac Newton b. Galileo Galilei c. Edwin Hubble d. Harlow Shapley e. Jill Tarter
b. Galileo Galilei
13. Your weird cousin, who is really into astronomy, decides that the return address he uses on his letters is incomplete! To his city, state, and country, he begins to add: "North America, Earth, Solar System..." If he now wants to include the name of the Galaxy's spiral-structure feature in which the Earth is located, how should his address end? a. Cygnus Arm b. Orion Spur c. Perseus Arm d. Sagittarius-Carina Arm e. Mars arm
b. Orion Spur
24. The first astronomer to show that spiral nebulae (today called spiral galaxies) have large Doppler shifts was a. Edwin Hubble b. Vesto Slipher c. Percival Lowell d. Christian Doppler e. Harlow Shapley
b. Vesto Slipher
18. Which of the following statements about dark matter in the Galaxy is FALSE? a. Most of it cannot at present be observed with our telescopes (we only know its existence from the gravity it exerts) b. While the dark matter cannot be observed with our present-day instruments, we still have a pretty good idea what it consist of c. Our measurements suggest that there may be as much as ten or twenty times more dark matter in the Galaxy than the matter we have been able to observe d. Dark matter appears to be distributed in a giant halo (outer layer) around the Galaxy e. We can pretty much rule out the idea that the dark matter is made mainly of vast clouds or regions of hydrogen gas
b. While the dark matter cannot be observed with our present-day instruments, we still have a pretty good idea what it consist of
6. About two thirds of the nearby spiral galaxies (which we can study in more detail) don't have a round central bulge, but instead show a. no central bulge at all, just a uniform galaxy b. a central bulge with a bar of stars in the middle c. a central bulge with a completely irregular and unsymmetric shape d. a central bulge with 2 giant jets coming out larger than the galaxy e. you can't fool me; all spirals have a round central bulge
b. a central bulge with a bar of stars in the middle
6. Einstein suggested that the regular change (advance) in the perihelion of the planet Mercury could be explained by: a. the presence of a planet inside the orbit of Mercury, whose gravity influenced Mercury b. a distortion in spacetime caused by the gravity of the Sun c. the pull of a small black hole that orbits our Sun so closely that we are not able to see it d. the presence of a strong magnetic field in the Sun, which causes huge outburst of material e. a distortion in our view of the solar system caused by the Earth's atmosphere
b. a distortion in spacetime caused by the gravity of the Sun
11. You suddenly get an uncontrollable urge to find out more about the other side of the Milky Way Galaxy (the regions beyond the center). Where should you rush off to? a. the control room of the Hubble Space Telescope at NASA b. a radio telescope that can observe at 21-cm wavelengths c. the control room of the Compton Gamma-Ray Observatory d. a gold mine near Lead, South Dakota e. the same factory that makes Snickers candy bars
b. a radio telescope that can observe at 21-cm wavelengths
15. Deep inside a black hole (and hidden from our view) is the compressed center, where all the "stuff" of the star goes. Astronomer call this central point a. an event horizon b. a singularity c. a time-stopping point d. a black dwarf e. Bayonne, New Jersey
b. a singularity
4. Which type of galaxy is observed to contain mostly older stars? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above
b. elliptical
9. The type of galaxy that consists almost entirely of old stars and is thus less blue (more yellow and reddish) than the other types is: a. spiral b. elliptical c. irregular d. barred spiral e. all of the above consist almost entirely of old stars
b. elliptical
3. What objects did Harlow Shapley use as "signposts" to figure out the extent of the Milky Way Galaxy and the location of its center? a. thick clouds of cold hydrogen giving off 21-cm radiation b. globular clusters c. HII regions d. dust clouds e. big arches advertising "billions and billions sold"
b. globular clusters
25. If I want to find a sizeable collection of Population II stars in the Milky Way Galaxy, where would be a good place to look? a. near the Sun b. in a globular cluster high above the Galaxy's disk c. in the Orion Spur d. on the outer surface of giant molecular clouds e. in an open cluster, especially one with a lot of dust in and around it
b. in a globular cluster high above the Galaxy's disk
17. If a galaxy contains a great deal of dark matter, then, compared to the mass-to-light ratio of the inner part, the mass-to-light ratio of the whole galaxy will be a. less b. more c. the same d. it depends on the type of galaxy e. it depends on the galaxy's red-shift
b. more
22. Which of the following is NOT part of the growing chain of evidence that makes many astronomers suspect there is a black hole at the very center of the Milky Way Galaxy? a. the motion of stars close to the center indicates that there is a mass of 4.6 million solar masses inside their orbits b. the Hubble Space Telescope has shown us a visible-light image of an accretion disk at the center of the Galaxy c. the existence of a strong radio source at the center whose size appears to be no larger than Jupiter's orbit d. the fact that Sagittarius A is a stationary radio source, while objects around it appear to be in motion e. the observation that matter in the central region continues to be falling in toward the center
b. the Hubble Space Telescope has shown us a visible-light image of an accretion disk at the center of the Galaxy
3. When astronauts aboard the International Space Station (ISS) in space let go of an orange, it just floats there. Why is that? a. the ISS is so far from the Earth, the gravity there is essentially zero b. the ISS is falling around the Earth, and in free fall, things feel no weight c. spacetime is so different aboard the ISS, that time stops, and so nothing can fall d. the law of gravity only works on the Earth, it doesn't work in space e. this is an unsolved problem in science, and so it is "fruitless" to worry about it
b. the ISS is falling around the Earth, and in free fall, things feel no weight
18. Once a black hole forms, the size of its event horizon is determined only by a. the size (diameter) of the star that collapsed into the black hole b. the mass inside the event horizon c. the time since the black hole formed d. the composition of the material that formed the black hole e. you can't fool me; every black hole has an event horizon of the same size
b. the mass inside the event horizon
8. According to Einstein's general theory of relativity, the stronger a star's gravity, a. the weaker its pull on another star will be b. the slower time runs near it c. the weaker the x-rays we see from it d. the smaller the event horizon will be of the black hole it makes e. the less space-time around it will be distorted
b. the slower time runs near it
32. The first time that astronomers observed both gravitational waves and electro-magnetic waves from the same event, what they were observing was: a. a supernova explosion in one of the closest galaxies to us b. the spiraling toward each other of two neutron stars c. a binary star system where a giant star is overloading a white dwarf with too much material d. the merger of two black holes with masses dozens of times the mass of our Sun e. the collapse of an entire cluster of stars into one big black hole
b. the spiraling toward each other of two neutron stars
5. Which of the following statements about the way the mass of a white dwarf affects spacetime is correct? a. the white dwarf mass will attract light, and pull it in a curved path; spacetime is not affected b. the white dwarf mass will curve spacetime; light has to follow that curvature c. the white dwarf mass will not affect spacetime at all; only black holes affect spacetime d. the white dwarf mass will have enough gravity to straighten out any curvature in spacetime; so spacetime near the white dwarf will be flat e. since no experiments have ever tested Einstein's theory of general relativity, it is impossible to say what will happen
b. the white dwarf mass will curve spacetime; light has to follow that curvature
27. The Andromeda Galaxy (our nearest spiral neighbor) has spectral lines that show a blue shift. From this we may conclude that: a. the universe is no longer expanding b. this particular nearby galaxy is moving toward us c. this galaxy has merged with the Milky Way and is now part of it d. this particular nearby galaxy is moving away from us e. this galaxy has an unusual number of very bright and hot O-type stars in it
b. this particular nearby galaxy is moving toward us
32. Before you can use Hubble's Law to get the distance to a galaxy, what observation must you make of that galaxy? a. you must find a Cepheid variable star in the galaxy b. you must take a spectrum of the galaxy and measure the red shift c. you must measure how strongly the galaxy emits radio waves at a wavelength of 21 centimeters d. you must find a Type Ia supernova that is exploding in that galaxy e. all you need to do is look at the galaxy through any telescope
b. you must take a spectrum of the galaxy and measure the red shift
26. Which of the following objects do many astronomers believe is a black hole? a. the nebula in Orion where new stars are seen to form (from dark dust clouds) b. the Crab Nebula c. Cygnus X-1 d. the open cluster called the Pleiades e. Bayonne, New Jersey
c. Cygnus X-1
17. The astronomer who first worked out the mathematical description of black hole event horizons was a. Edwin Hubble b. Jocelyn Bell c. Karl Schwarzschild d. S. Chandrasekhar e. Frederik Pohl
c. Karl Schwarzschild
33. The astronomer who assisted Edwin Hubble at the Mount Wilson Observatory and helped him establish the expansion of the universe was: a. Vesto Slipher b. Harlow Shapley c. Milton Humason d. Immanuel Kant e. James Kirk
c. Milton Humason
31. Why is the use of Hubble's Law to measure distances to galaxies so important to astronomers? a. They have NO other way of measuring distances to galaxies - absolutely none b. Many galaxies don't move away from us, so when we find one that does, it's really a big deal c. Most galaxies are so far away, the only way to get distances to them is to use Hubble's Law d. The other ways of getting distances only work for really far away galaxies; so the Hubble Law is the only way to measure distances to nearby galaxies e. It's stretching the truth to say that Hubble's Law is a really important way to get distances to galaxies; really, it's no more important than any other method
c. Most galaxies are so far away, the only way to get distances to them is to use Hubble's Law
5. Astronomers today know a lot about the size and shape of the Milky Way Galaxy. Which of the following common objects most resembles the shape of our Galaxy? a. a beach ball b. a flag, fluttering in the breeze c. a CD or DVD d. a cake e. a glazed donut
c. a CD or DVD
21. Astronomers now think that there is a black hole with more than 4 million times the mass of our Sun at the center of our Galaxy? Roughly how large would the event horizon of such a supermassive black hole be? a. the size of our Moon b. about 4 light years across c. about 17 times the size of the Sun d. about the size of an atom (so much mass really compresses the event horizon) e. we can't answer this question without knowing exactly what kind of stars were swallowed by the black hole
c. about 17 times the size of the Sun
7. Astronomers now know that surrounding the main body of our Galaxy (which our various kinds of telescopes have shown to us) and our fainter halo of stars there is a. only the empty space that lies between galaxies b. a series of hundreds and hundreds of nearby small galaxies, held in place by the Milky Way's gravity c. an invisible halo made of what astronomers are calling "dark matter" d. a set of huge clouds with many interesting molecules (like alcohol, carbon monoxide, and ammonia) in them e. a pair of long, bright jets of materials produced by a massive black hole and its accretion disk
c. an invisible halo made of what astronomers are calling "dark matter"
28. Astronomers have concluded that growing supermassive black holes (which have millions of times the Sun's mass or more) is pretty unlikely at our location in the Milky Way Galaxy. Where do they think is the most likely place in the Milky Way for such a supermassive black hole? a. at the outer edge of the Galaxy's disk, where there is less pull from other stars b. where a neutron star has already formed c. at the center of the Milky Way Galaxy, where matter is more crowded d. at the location astronomers call Cygnus X-1 e. no place in our Galaxy is likely for a really massive black hole
c. at the center of the Milky Way Galaxy, where matter is more crowded
26. Astronomers observe the Small Magellanic Cloud (SMC), a not very dense, rather small galaxy near us. They notice that even those stars that formed recently have relatively few heavier elements (when compared to such recent stars in our Milky Way.) What is the likely explanation for this deficiency? a. most stars in the SMC don't produce their energy through the process of nuclear fusion b. most stars in the SMC finished going through their lives many billions of years ago c. because the SMC is small and its stars are widely spaced, the rate of star formation (and star death) is much slower there d. in small galaxies, only low-mass stars can form (and these do not produce supernovae) e. astronomers cannot come up with any explanation for this puzzling observation
c. because the SMC is small and its stars are widely spaced, the rate of star formation (and star death) is much slower there
1. One of the most important observations in the history of astronomy was the one by Edwin Hubble that established that there are other galaxies, quite removed from the Milky Way. How did Hubble show this? a. by debating with Harlow Shapley and being more eloquent b. by observing a supernova explosion in a nearby galaxy, using it as a "standard bulb" c. by observing a Cepheid variable in a nearby galaxy and using it to get the distance d. by measuring the distances to many globular clusters using parallax e. by going to see Einstein, who knew the answers to these kinds of questions
c. by observing a Cepheid variable in a nearby galaxy and using it to get the distance
10. Which type of galaxy is very difficult to see, but (astronomers recently realized) may be very common? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above
c. dwarf elliptical
2. If you are in a freely falling elevator near the top of a tall building, as the elevator falls, your weight would be: a. the same as your usual weight b. a bit less than your usual weight c. equal to zero - you would be weightless d. a little more than your usual weight e. so great that you would be pressed to the floor and in great pain
c. equal to zero - you would be weightless
18. One of the main projects being carried out by the Hubble Space Telescope is to measure the distances of galaxies located in groups dozens of millions of lightyears away. What method do astronomers use with the Hubble to find such distances? a. constructing H-R diagrams b. measuring the parallax over a period of a decade or so c. finding Cepheid variables and measuring their periods d. measuring the x-rays given off by the accretion disks around massive black holes e. measuring the amount of dust in the disk of the galaxy
c. finding Cepheid variables and measuring their periods
15. Which is one reason that the typical galaxy's mass-to-light ratio (in units of the Sun's mass over the Sun's luminosity) generally greater than 1? a. galaxies contain mostly stars much brighter than the Sun b. galaxies contain mostly stars much more massive than the Sun c. galaxies contain many more stars that shine much less brightly than the Sun d. most of the mass in a galaxy is in the form of dust e. this is an unsolved problem in astronomy; scientists have no clue
c. galaxies contain many more stars that shine much less brightly than the Sun
26. In a distant galaxy, whose light is just arriving from 10 billion light years away, our spectroscope should reveal that the most common element is a. helium b. carbon c. hydrogen d. iron e. Einsteinium
c. hydrogen
24. Where would you look for the youngest stars in the Milky Way Galaxy? a. in the halo b. where there is dark matter c. in the disk d. in the nuclear bulge e. you can't fool me; my chances of finding a very young star are the same, wherever in the Galaxy I look
c. in the disk
16. If a galaxy contains a great deal of "dark matter," what will that do the galaxy's mass-to-light ratio? a. increase it a small amount b. decrease it a small amount c. increase it quite a bit d. decrease it quite a bit e. not affect it in any way (since it's dark matter)
c. increase it quite a bit
29. According to Hubble's Law, if two galaxies are not part of our Local Group, and galaxy B is three times farther away from us as Galaxy A, then Galaxy B will a. move toward us three times faster than A b. move away from us nine times faster than A c. move away from us three times faster than A d. move toward us nine times faster than A e. move away from us at about the same speed as A
c. move away from us three times faster than A
33. Some years after college (and after you recover from your astronomy class,) you get married and exchange gold rings with your sweetheart. What connection is there between the gold in those rings and recent observations of gravitational waves? a. gold atoms are only produced in supernova explosions, and all the gravitational wave events we have detected so far are from supernovae b. gold is so valuable (and so rare) because there it is only produced in the accretion disks of black holes, and most of it falls into the black hole c. our new understanding is that significant amounts of gold in the universe are produced in the mergers of neutron stars, which can be detected with gravitational waves d. gold is produced when two black holes merge, and most of the gravitational waves we have detected are from black hole mergers e. this is a misleading question; there is no connection whatsoever between gold and gravitational wave events
c. our new understanding is that significant amounts of gold in the universe are produced in the mergers of neutron stars, which can be detected with gravitational waves
23. Astronomers believe that the center of our Galaxy has a black hole with enough mass inside to make almost 4 million Suns! How do astronomers think a black hole could acquire so much mass? a. the Galaxy formed from one supergiant star, and most of what is left of it is now in the black hole b. the black hole at the center is really another galaxy that our Milky Way swallowed; none of its material comes from our own Galaxy c. the center of our Galaxy is a much more crowded region than where the Sun is found; we still see material falling toward the center and material has fallen in for billions of years d. this black hole contains only dark matter, and we know dark matter is concentrated toward the center of our Galaxy; none of it can be found near the outer regions of the Milky Way e. no one can think of a way to make a black hole this massive; that's why most astronomers are skeptical about the observations that indicate that our Galaxy has such a black hole
c. the center of our Galaxy is a much more crowded region than where the Sun is found; we still see material falling toward the center and material has fallen in for billions of years
9. In 1959, Pound and Rebka did an experiment to test the prediction of Einstein's theory of general relativity about the relationship between the pace of time and the strength of gravity. When two identical atomic clocks, one on the ground floor and one on the top floor, were compared, a. the clocks ran at exactly the same pace in both locations b. the clock on the top floor ran a tiny bit slower c. the clock on the ground floor ran a tiny bit slower d. the clock on the ground floor became a little bit lighter (weighed less) e. the clock on the top floor became a little bit lighter
c. the clock on the ground floor ran a tiny bit slower
1. William Herschel thought that the Sun and Earth were roughly at the center of the great grouping of stars we call the Milky Way. Today we know this is not the case. What was a key reason that Herschel did not realize our true position in the Milky Way? a. he did not have a telescope, and most stars are too far away to see without a telescope b. his telescope was only able to show him objects inside the solar system, and not objects in the Galaxy c. the dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of the Milky Way that surrounds us d. there are so many black holes in the Galaxy, that they absorb a substantial part of the light from distant objects; we needed x-ray astronomy to see to more distant regions e. Herschel shared with ancient people the firm religious belief that we must be the center of everything
c. the dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of the Milky Way that surrounds us
1. The equivalence principle (principle of equivalence) says that a. the amount of energy released by fusion is equivalent to the amount of mass that is lost b. gravity is equivalent the strong nuclear force is inside any nucleus c. the effects of gravity are equivalent to the effects of acceleration d. far away from a black hole, its pull is equivalent to the pull of the star that it formed from e. the event horizon of a black hole is equivalent to the place where things are forever trapped
c. the effects of gravity are equivalent to the effects of acceleration
31. In the first direct detection of gravitational waves by LIGO in 2015, the waves came from a. the collapse of a nearby star into a white dwarf b. a supernova explosion in a nearby galaxy c. the merger of two black holes d. the rapid motion of three hot Jupiter planets around a nearby star e. the dashed hopes of all the people in the U.S. who want their government to work well for them
c. the merger of two black holes
28. What leads astronomers to conclude that the proto-galactic cloud (the cloud from which our Galaxy formed) was roughly spherical? a. all black holes have spherical event horizons b. the shape of the disk and spiral arm of the Milky Way Galaxy is spherical, so the original cloud must have been too c. the oldest stars in the Galaxy (Population II stars, globular clusters) form a spherical halo around the Galaxy; they outline the original shape of the cloud that gave the Galaxy birth d. since the Big Bang that made everything was spherical, all structures in the universe must also be spherical e. actually, astronomers believe the original proto-galactic cloud was in the shape of a flat disk, like the Galaxy is now
c. the oldest stars in the Galaxy (Population II stars, globular clusters) form a spherical halo around the Galaxy; they outline the original shape of the cloud that gave the Galaxy birth
8. Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies? a. their brightness b. their overall color c. their shape d. their abundance of the element iron e. their Doppler Shift
c. their shape
16. How do astronomers measure the mass that the Galaxy contains inside the orbit of the Sun? a. they count the number of stars one by one and multiply by the average mass of a star b. they add up all the observations at 21-cm wavelengths (because the mass of hydrogen gas is far greater than the mass in all the stars) c. they measure the distance to the center of the Galaxy and the period of the Sun's orbit and then use Kepler's Third Law d. they measure the masses of many other spiral galaxies nearby and then take an average e. you can't fool me; there is no way to get the mass of something as big as our Galaxy
c. they measure the distance to the center of the Galaxy and the period of the Sun's orbit and then use Kepler's Third Law
15. Objects orbiting around the center of the Milky Way obey Kepler's 3rd Law. This means that: a. the pull of gravity gets stronger and stronger as you get further away from the center b. larger clusters of stars will orbit the center more quickly than smaller ones c. the closer a star is to the center, the longer it will take to go around d. a cloud of gas or star that is further from the center will generally take more time to orbit e. the orbits of all objects around the Galaxy are in the shape of a perfect circle
d. a cloud of gas or star that is further from the center will generally take more time to orbit
12. According to the general theory of relativity, light and other radiation coming from a white dwarf or a neutron star should (and experiments show that it does) exhibit a. reddening, where the bluer colors are more effectively absorbed or scattered by dust b. a very strong blue shift c. motion in a perfect circle around the white dwarf and neutron star d. a gravitational redshift e. absolutely no difference in characteristics when compared to light coming from any star
d. a gravitational redshift
31. In the future, astronomers believe that the Milky Way Galaxy has additional collisions in store. Which of the following nearby galaxies are eventually going to collide with our own? a. the Small Magellanic Cloud b. the Large Magellanic Cloud c. the Andromeda Galaxy (M-31) d. all of the above e. none of the above
d. all of the above
4. According to the general theory of relativity, the presence of mass a. causes motion at the speed of light squared b. is equivalent to the presence of light c. causes curved paths to straighten out until they are exactly straight lines d. causes a curvature (or warping) of spacetime e. will cause a black hole to form, unless there is motion
d. causes a curvature (or warping) of spacetime
12. Which of the following statements about the different types (shapes) of galaxies is correct? a. whatever type a galaxy is at its birth, that's what it will be for all time b. all galaxies start out as ellipticals, but some later evolve to be spirals and irregulars c. 90% of all galaxies are spirals (including our Milky Way); the other two types are very unusual d. collisions and mergers between galaxies can sometimes change a galaxy's type (shape) e. what type we see a galaxy to be just depends on the angle at which we happen to see it; all galaxies look roughly the same in shape
d. collisions and mergers between galaxies can sometimes change a galaxy's type (shape)
19. What method would astronomers use to find the distance to a galaxy so far away that individual stars are impossible to make out (resolve)? a. parallax b. Cepheid variables c. using the x-ray emission from the entire galaxy d. finding the redshift and using Hubble's Law e. the turnoff point of the main sequence on an H-R diagram
d. finding the redshift and using Hubble's Law
27. When one member of a binary star system is a black hole, and astronomers detect flickering x-rays coming from the system, where are these x-rays usually coming from? a. from inside the black hole event horizon b. from the photosphere of the companion star (the star that is not a black hole) c. from the singularity d. from a disk of material around the black hole (material that has been pulled from the companion star and is falling toward the black hole) e. from a distant galaxy that just happens to lie behind the black hole system (astronomers discovered that such x-rays have nothing to do with the black hole)
d. from a disk of material around the black hole (material that has been pulled from the companion star and is falling toward the black hole)
29. What is a key reason that gravitational waves are so much harder to detect than electro-magnetic (e-m) waves? a. gravitational waves don't create any kind of disturbance the way e-m waves do b. gravitational waves are so strong, they really shake our detectors, making measurements difficult c. gravitational waves get all mixed up with sound waves in the Earth's atmosphere, and are therefore hard to distinguish from all the sound d. gravitational waves are much weaker than e-m waves, and therefore require very, very precise equipment to detect e. you can't fool me; gravitational waves are much easier to detect than e-m waves
d. gravitational waves are much weaker than e-m waves, and therefore require very, very precise equipment to detect
23. A handsome, rich, but vain movie star notices that he is starting to age, and consults you as his astronomy expert, to see if you can find an astronomical way to slow down his aging. Putting aside practical considerations (such as the fact that we cannot travel to other stars), which of the following strategies would IN THEORY allow him to age more slowly than the rest of humanity. a. he should always live at sea level on Earth, and never go to any mountains or high altitudes b. he should live far away from the gravity of any planet or star (in a deep-space station) c. he should be in orbit around the Earth, and expose himself to as many cosmic rays as possible d. he should travel to a black hole, and spend some time in orbit just above the event horizon e. he should live in a room filled with positive electrical charge
d. he should travel to a black hole, and spend some time in orbit just above the event horizon
30. Which of the following statements about the implications of Hubble's Law is FALSE? a. the law implies that the whole universe must be expanding b. the law can be used to measure distances to remote galaxies for which we can measure a Doppler shift c. the law does NOT require us to be at the center of the expanding universe d. if you were observing the universe from a distant galaxy, you would NOT see all the galaxies (except those in your own group) moving away from YOU e. although galaxies move away from each other, they themselves are not expanding in size
d. if you were observing the universe from a distant galaxy, you would NOT see all the galaxies (except those in your own group) moving away from YOU
30. What was especially noteworthy about the Sagittarius Dwarf Galaxy when it was discovered among the small galaxies near the Milky Way? a. it was so large in mass, astronomers could not understand how the Milky Way wasn't flying toward it b. it had a supermassive black hole in the center much larger than the Milky Way's c. it was rotating so quickly that it could not hold together for very long d. it was on a collision course with the Milky Way and would be swallowed by it eventually e. it was made entirely of dark matter and so could not be seen on any photographs
d. it was on a collision course with the Milky Way and would be swallowed by it eventually
25. Far away from a black hole (at the distance of another star), which of the following is a possible way to detect it? a. notice what a large amount of star light it blocks from behind it b. look for the pulsed radio waves it gives off as it rotates like a lighthouse c. look for the neutrinos that escape from the event horizon d. search for flickering x-rays being given off from an accretion disk around the black hole, as it "eats" part of a neighbor star e. you can't fool me, you can never, ever detect a black hole!
d. search for flickering x-rays being given off from an accretion disk around the black hole, as it "eats" part of a neighbor star
14. Compared to the mass of our own Milky Way Galaxy, the total mass we estimate for the Andromeda Galaxy is a. a lot smaller b. a little bit smaller c. exactly the same d. somewhat bigger e. not something we can measure
d. somewhat bigger
22. The Tully-Fisher relation (looking at rotation speeds) only works for: a. elliptical galaxies b. the very closest galaxies, within a few dozen million light-years c. galaxies that have a Type Ia supernova explosion in them d. spiral galaxies e. galaxies that we are observing from right around the time of the big bang
d. spiral galaxies
22. When scientists say that "black holes have no hair", what do they mean? a. that the event horizon of a black hole is very smooth and does not have parts that jut out b. that if you threw something toward a black hole (a rabbit, say) it would quickly be ripped apart into smaller pieces c. that time near a black hole slows down so much our hair would not grow at a normal rate d. that once a black hole forms, very little information can be extracted from it about the material that is now inside e. no one knows what this means; regular people are not meant to figure out some of the weird things physicists say about black holes
d. that once a black hole forms, very little information can be extracted from it about the material that is now inside
2. The new instrument that made it possible for Edwin Hubble to demonstrate the existence of other galaxies in the early 1920's was: a. the Hubble Space Telescope (that's why we named it after Hubble!) b. the 300-ft radio telescope in West Virginia c. a kind of electronic detector called a CCD d. the 100-inch reflector on Mount Wilson e. an infra-red telescope carried aboard one of the early airplane flights by the Wright Brothers
d. the 100-inch reflector on Mount Wilson
8. Which of the following statements about the nuclear bulge of our Galaxy is FALSE? a. it is significantly thicker than the disk of the Galaxy b. it typically consists of older stars c. it is difficult for us to see with visible light because of cosmic dust d. the best way to learn more about it is to observe higher energy radiation, such as ultraviolet and x-rays e. there is evidence that it is not exactly spherical, but elongated
d. the best way to learn more about it is to observe higher energy radiation, such as ultraviolet and x-rays
14. The region around a black hole where everything is trapped, and nothing can get out to interact with the rest of the universe, is called a. the singularity b. the neutron star radius c. the gravitational redshift zone d. the event horizon e. day-time television
d. the event horizon
14. A "galactic year" as defined by astronomers is: a. the time it takes the Earth to go around the Sun (starting with when it's closest in its orbit to the center of the Galaxy) b. the time it takes the outermost part of the solar system (the Oort Cloud) to rotate once relative to the Galaxy) c. the time it took the Milky Way Galaxy to develop spiral arms d. the time it takes the Sun to revolve once around the center of the Milky Way Galaxy e. the time it will take the Sun to become a red giant and expand into the Galaxy
d. the time it takes the Sun to revolve once around the center of the Milky Way Galaxy
17. Recently, astronomers have observed stars and other objects that orbit the center of the Milky Way Galaxy farther out than our Sun, but move around faster than we do. How do astronomers think such an observation can be explained? a. all these faster-moving objects must be escaping from the gravity of the Milky Way and will soon be lost to our Galaxy b. each of the faster-moving outer objects must be the result of a supernova explosion (giving them extra speed) c. it is the Sun that is moving too slowly because of a collision billions of years ago; the outer objects are really moving at the appropriate speed for their distance from the center d. there must be a great deal of invisible dark matter outside the orbit of the Sun whose gravitational pull explains the faster motions we see out there e. no one can come up with any explanation for this puzzling observation
d. there must be a great deal of invisible dark matter outside the orbit of the Sun whose gravitational pull explains the faster motions we see out there
21. The reason type Ia supernovae are useful to astronomers for determining distances to other galaxies is that a. they only occur in spiral galaxies, for which no other way of getting distances is available b. it is easy to measure the blueshift produced by such explosions c. they are much larger than many other objects that can be seen in galaxies d. they are very bright, and generally reach the same peak luminosity e. they produce very energetic pulsars whose radio radiation can be detected across vast distances
d. they are very bright, and generally reach the same peak luminosity
4. What have we learned from the work of Harlow Shapley and others about the location of the Sun in the Milky Way Galaxy? a. we are almost exactly in the center of a giant flat pinwheel b. we are very close the edge of the visible disk of the Galaxy, more than 50,000 LY from the center c. we are high above the disk of the Galaxy, about as far away as the most distant globular cluster d. we are in the disk of the Galaxy, about 3/5 of the way from the center e. you can't fool me; because of all the dust, astronomers still have no idea where our Sun is located in the Milky Way Galaxy
d. we are in the disk of the Galaxy, about 3/5 of the way from the center
5. Which of the following is NOT a characteristic of a spiral galaxy? a. most of its material is in the shape of a flattened disk b. it has quite a bit of gas and dust in it c. it has young stars and bright emission nebulae d. when we take spectra of its stars, they have far less of the heavier elements than the Sun e. the bright stars in it can be seen organized into distinct spiral arms
d. when we take spectra of its stars, they have far less of the heavier elements than the Sun
19. Astronomers making observations in our Galaxy have been able to rule out a number of suggestions for what the dark matter in the Galaxy might be. Which of the following have we NOT been able to rule out (which suggestion is still "in the running")? a. black holes b. hydrogen gas that is at low temperatures compared to stars c. Jupiter-mass planets or brown dwarfs d. large quantities of dust (like we find in nebulae) e. a new kind of subatomic particle
e. a new kind of subatomic particle
10. When a light wave leaves a region of strong gravity, compared to the same wave leaving a spaceship in empty space, the wave in strong gravity will have a. a longer wavelength b. a lower frequency c. less energy d. a gravitational redshift e. all of the above
e. all of the above
27. The Population I stars in the Milky Way Galaxy a. include the Sun b. show a wider range of ages than Population II stars c. generally contain a greater percentage of heavier elements than Population II stars d. are generally found in the disk of the Galaxy e. all of the above
e. all of the above
20. Suppose each of the following objects could collapse into a black hole. Each black hole would have a sphere around it that is the limit for escape -- once you are inside this region, you cannot get away. For which object would this region be the largest in diameter? a. a star with the mass of our Sun b. a planet like Jupiter c. a star that was type O when it was on the main sequence d. an entire cluster of stars (with about 150 stars in it) e. an entire galaxy of stars (with about a billion stars in it)
e. an entire galaxy of stars (with about a billion stars in it)
7. When Einstein proposed his General Theory of Relativity, he suggested some pretty strange ideas about space, time, and gravity. How did scientists in 1919 show that Einstein's theory described the behavior of the real world and wasn't just a crazy hypothesis? a. by finding x-rays from a black hole b. by using an H-R diagram for a nearby cluster of stars c. by discovering the process of nuclear fusion d. by dropping different weights from very tall buildings e. by observing starlight coming close to the Sun during an eclipse
e. by observing starlight coming close to the Sun during an eclipse
28. Which of the following was not done by Edwin Hubble? a. measuring the distance to the Andromeda "nebula" b. classifying the galaxies by their shapes c. establishing the expansion of the universe d. discovering the law that the motion of the galaxies away from us follows e. discovering the relationship between period and luminosity of a cepheid variable
e. discovering the relationship between period and luminosity of a cepheid variable
9. An astronomer needs to measure the distance to a globular cluster of stars that is part of the Milky Way Galaxy. What method should she try to use to find the distance? a. measure the parallax of the cluster b. count the number of O and B type stars in the cluster c. look for flickering x-rays coming from a black hole in a binary star system in the cluster d. measure the red-shift of the cluster e. find a variable star (cepheid or RR Lyrae) in the cluster
e. find a variable star (cepheid or RR Lyrae) in the cluster
13. A graduate student in astronomy needs to measure the mass of a spiral galaxy she is studying for her PhD thesis. Which of the following observations would be important for her to make? a. determine whether or not there is evidence for a massive black hole at the galaxy's center b. construct an H-R diagram for a prominent open cluster in the galaxy's disk c. measure the gamma-ray emission from the galaxy d. compare the overall color of the galaxy to other galaxies of the same type e. obtain the speed at which stars or gas near the outer regions of the galaxy are moving around
e. obtain the speed at which stars or gas near the outer regions of the galaxy are moving around
25. Edwin Hubble was able to show that (with the exception of our nearest neighbors) the farther a galaxy is from us, the a. brighter it looks b. bluer its color c. the later in its life we are seeing it d. the larger its halo is e. the faster it is moving away from us
e. the faster it is moving away from us
16. In the far future, a starship becomes trapped inside the event horizon of a black hole. Although the crew discovers that their ship cannot out, they at least want to send a message to other ships in the area to stay away from the danger zone. If they send out a message in the form of a radio wave, what will be its fate? a. the message will emerge from the event horizon with a huge gravitational redshift b. although the radio wave will emerge from the event horizon, all the information in the message will be garbled c. the radio wave will become a gamma ray by the time it emerges from the event horizon d. the radio wave will only emerge from the event horizon if it is moving in the direction of the magnetic north and south pole of the star that formed the black hole e. the message will never emerge from the event horizon
e. the message will never emerge from the event horizon
29. Which of the following is evidence that the formation process of our Galaxy may have included collisions with smaller neighbor galaxies? a. the presence of millions of new stars, recently formed from clouds of gas and dust b. the existence of supernova remnants, such as the Crab Nebula, in the Galaxy's disk c. the observation that objects outside the orbit of the Sun are moving around the Galaxy faster than we expected d. the observation that globular cluster are arranged in a spherical "halo" around the Galaxy e. the observation of long moving streams of stars that continue to orbit through our Galaxy's halo
e. the observation of long moving streams of stars that continue to orbit through our Galaxy's halo
19. Which of the following can a black hole not "eat" (swallow)? a. a planet b. a cloud of gas and dust c. a star d. another black hole e. you can't fool me, black holes can eat anything
e. you can't fool me, black holes can eat anything
