PHYS exam 4 Ch. 14-16 and 18.

Term
1 / 42
The size of the Milky Way is determined from studying __________________ in globular clusters.
Choose one:
A. standard candles
B. standard models
C. velocitiesD. expansions
Click the card to flip 👆
Terms in this set (42)
The size of the Milky Way is determined from studying __________________ in globular clusters.
Choose one:
A. standard candles
B. standard models
C. velocitiesD. expansions
A. standard candles
Astronomers observe two galaxies, A and B. Galaxy A has a recession velocity of 2,500 km/s, while galaxy B has a recession velocity of 5,000 km/s. This means that
Choose one:
A. galaxy A is twice as far away as galaxy B.
B. galaxy A is four times as far away as galaxy B.
C. galaxy B is twice as far away as galaxy A.
D. galaxy B is four times as far away as galaxy A.
C. galaxy B is twice as far away as galaxy A.
Evidence of a supermassive black hole at the center of the Milky Way comes from
Choose one:
A. strong radio emission from the region of the accretion disk.
B. All answer choices are correct.
C. direct observations of stars that orbit it.
D. X-rays from material that is falling in.
B. All answer choices are correct.
The orbits of stars in the bulges of spiral galaxies most closely resembles the orbits of:
Choose one:
A. objects in the Kuiper Belt.
B. stars in the disk of a spiral galaxy.
C. planets in the solar system.
D. stars in an elliptical galaxy.
D. stars in an elliptical galaxy.
The orbits of stars in elliptical galaxies:
Choose one:
A. are all in the same direction.
B. have random orientations.
C. have many different objects at the focus.
D. are all circular.
B. have random orientations.
The distances to galaxies used to establish Hubble's law are found from:
Choose one:
A. spectroscopic parallax.
B. radar.
C. parallax.
D. standard candles, such as supernova.
D. standard candles, such as supernova.
In every direction that astronomers look, they see the same Hubble's law, with the same slope. This is an example of
Choose one:
A. energy balance.
B. hydrostatic equilibrium
.C. homogeneity.
D. isotropy.
D. isotropy.
Supermassive black holes
Choose one:
A. occur in most, perhaps all, large galaxies.
B. occur only in the space between galaxies.
C. are extremely rare. There are only a handful of them in the universe.
D. are completely hypothetical.
A. occur in most, perhaps all, large galaxies.
Supermassive black holes:
Choose one:
A. are a recent development in the universe's history.
B. are an as yet untested hypothesis.
C. are "fed" by disturbed gas when galaxies interact.
D. gradually consume their host galaxies.
C. are "fed" by disturbed gas when galaxies interact.
The light that comes to us from active galactic nuclei comes from a volume about the size of
Choose one:
A. the bulge of the Milky Way.
B. the Solar System.
C. a globular cluster.
D. Earth.
B. the Solar System.
All the light in an AGN outburst is emitted Choose one: A. from the same place. B. at the same time. C. in one color. D. at the same frequency.B. at the same time.All the light in an AGN outburst travels Choose one: A. at the same speed. B. with the same frequency. C. to the same destination. D. in the same direction.A. at the same speed.The length of time that it takes for the light from the outburst to pass the observer indicates Choose one: A. the size of the observer. B. the distance to the AGN. C. the size of the AGN. D. the duration of the outburst.C. the size of the AGN.Currently, star formation rates are highest inspiral galaxiesGalaxies are classified according to theirshapeIn astronomy, isotropy means that the universe is the same __________, and homogeneity means that the universe is the same __________. Choose one: A. in all locations; in all directions B. in all directions; in all locations C. at all size scales; at all times D. at all times; at all size scalesB. in all directions; in all locationsHubble's law was discovered using measurements of two properties of a galaxy: _______ and _______. Choose one: distance; rotation speed distance; recession velocity size; recession velocity size; massdistance; recession velocityGlobular clusters are important to understanding the Milky Way because Choose one: A. the stars in them are highly enhanced in metals. B. they reveal the size of the Milky Way and Earth's location in it. C. they are so young that they provide information about current star formation. D. they provide information about dwarf ellipticals from which the Milky Way formed.B. they reveal the size of the Milky Way and Earth's location in it.What property of these stars can we measure to determine how much mass is at the center of the galaxy? Choose one: A. their total luminosity B. their velocities as they orbit the center C. their ages D. their average spectral typeB. their velocities as they orbit the centerConsidering the following objects and their properties, which is most likely to exist at the very center of our galaxy? Choose one: A. an extremely massive star B. a supermassive black hole C. a giant molecular cloud D. a clump of dark matter E. a globular clusterB. a supermassive black holeBased on what you have learned, which of the following measurements would we use to determine which galaxies are moving toward or away from the Milky Way? Choose one: A. the parallax angle of the galaxy B. the total luminosity of the galaxy C. the Doppler shift of spectral lines within the galaxy's spectrum D. the width of spectral lines within the galaxy's spectrumC. the Doppler shift of spectral lines within the galaxy's spectrumThe best evidence for dark matter in the Milky Way comes from the observation that the rotation curve Choose one: A. rises swiftly in the interior. B. is quite flat at great distances from the center. C. falls off and then rises again. D. has a peak at about 2,000 light-years from the center.B. is quite flat at great distances from the center.In spiral galaxies, stars form predominantly in: Choose one: A. the arms of the disk. B. the bar. C. the halo. D. the bulge.A. the arms of the disk.In general, older stars have lower __________ than younger stars. Choose one: A. rotation rates B. luminosities C. abundance of heavy elements D. orbital speedsC. abundance of heavy elementsLooking toward the galactic center, we see no redshift or blueshift. This tells us: Choose one: A. the Milky Way is stationary with respect to other galaxies. B. the Sun is stationary with respect to the center of the galaxy. C. the center of the galaxy is motionless. D. the Sun and the center are not moving toward or away from each other.D. the Sun and the center are not moving toward or away from each other.In general, the Milky Way has: Choose one: A. the same chemical composition as time passes. B. more abundant heavy elements as time passes. C. less abundant heavy elements as time passes. D. more abundant hydrogen as time passes.B. more abundant heavy elements as time passes.Cosmic rays are Choose one: A. a form of electromagnetic radiation. B. high-energy particles. C. high-energy photons. D. high-energy dark matter.B. high-energy particles.In the Hubble scheme for classifying galaxies, what type of galaxy is the Milky Way? Choose one: A. irregular B. barred spiral C. elliptical D. spiralB. barred spiralWhere are the youngest stars in the Milky Way Galaxy? Choose one: A. in the core B. in the bulge C. in the halo D. in the diskD. in the diskWhich of the following statements are true of the Milky Way? Choose one or more: A. The Milky Way has globular clusters. B. The Milky Way is mostly dark matter .C. The Milky Way has two major arms. D. The Milky Way is an elliptical galaxy.ABCIf the main-sequence turnoff of a star cluster occurs near the very top of the main sequence, then the cluster is Choose one: A. very dense. B. very old. C. very hot. D. very young.D. very young.Which of the following contributes the largest percentage of total mass of a spiral galaxy? Choose one: A. central black hole B. dust and gas C. stars D. dark matterD. dark matterAstronomers know that dark matter is present in galactic halos because the speeds of orbiting stars _________ far from the center of the galaxy. Choose one: increase decreasefluctuate dramatically remain about constantremain about constantWhich property is detectable for both dark matter and the supermassive black hole at the center of the Milky Way? Choose one: A. temperature B. gravity C. composition D. luminosityB. gravityHow do astronomers detect dark matter? Choose one: A. by determining how fast more distant galaxies recede B. by measuring the amount of background light blocked C. by comparing luminous mass to gravitational mass D. by measuring the amount of X-rays emittedC. by comparing luminous mass to gravitational massDetailed observations of the structure of the Milky Way are difficult because Choose one: the Milky Way is mostly dark matter. there are too many stars in the way. the Solar System is embedded in the dust and gas of the disk. the galaxy is rotating too fast (about 200 kilometers per second).the Solar System is embedded in the dust and gas of the disk.hich of the following pieces of evidence support(s) the theory that the Milky Way is a spiral galaxy? Choose one or more: A. The 21-cm radiation emitted from neutral hydrogen clouds shows the existence of spiral arms. B. Most stars in our galactic neighborhood share the same relative motion around the galactic center. C. A supermassive black hole lies at the galactic center. D. Ongoing star formation occurs in clouds of gas and dust.ABDOlder stars are found farther from the midplane of a galactic disk because Choose one: A. the disk used to be thicker. B. old stars come from the halo. C. the younger stars in the thick disk were more massive and already died. D. the stars have lived long enough to move there.D. the stars have lived long enough to move there.What is at the very center of our galaxy? This question is difficult to answer because the center is completely obscured to our eyes behind a large amount of dust. On the basis of what you know about dust from previous chapters, what can be done to improve our view of the galaxy's center?Choose one: A. Observe it in the infrared. B. Observe it with a higher-resolution telescope. C. Observe it with a blue filter. D. Observe it with a space telescope.E. Calculate how much light has been absorbed by the dust and mathematically add it back into images of the center.A. Observe it in the infrared.On the basis of the colors and lifetimes of different types of stars, which of the following statements best describes the current state of the bulge and disk? Choose one: A. It is impossible to tell whether new stars are forming just from color alone. B. New stars are forming inside both the disk and the bulge at about the same rate. C. New stars are forming mostly in the disk. D. New stars are forming mostly in the bulge.C. New stars are forming mostly in the disk.Think about what you have learned about stars and galaxies so far, and determine which of the following statements is correct. Choose one: A. Red stars form in between the spiral arms, whereas blue stars form inside them. B. Both red and blue stars form everywhere equally within the disk of the galaxy, then something happens to clear the blue stars out from in between the arms. C. Both red and blue stars form inside the spiral arms. Then both stars begin to move out of the arms, but the blue stars die before they can get very far. D. Both red and blue stars form inside the spiral arms. Then the red stars move out of the arms, while the blue stars stay inside them.C. Both red and blue stars form inside the spiral arms. Then both stars begin to move out of the arms, but the blue stars die before they can get very far.What types of stars indicate recent star formation in a region? Choose one: A. long-lived, cool, low-mass stars, like O- and B-type stars B. short-lived, cool, low-mass stars like K- and M-type stars C. short-lived, hot, massive stars, like O- and B-type stars D. long-lived, cool, low-mass stars, like K- and M-type starsC. short-lived, hot, massive stars, like O- and B-type stars