Right Astronomy Final
According to general relativity, why does Earth orbit the Sun? A) Earth is following the straightest path possible, but spacetime is curved in such a way that this path goes around the Sun. B) Earth and the Sun are connected by a "ropelike" set of invisible, subatomic particles. C) The mysterious force that we call gravity holds Earth in orbit.
A
Astronomers estimate that new stars form in our galaxy at the rate of about A) a few (2-3) per year. B) 100 per year. C) 20-30 per year. D) ten per year. E) one per year
A
Degeneracy pressure is the source of the pressure that stops the crush of gravity in all the following except A) a very massive main-sequence star. B) a neutron star. C) a brown dwarf. D) a white dwarf. E) the central core of the Sun after hydrogen fusion ceases but before helium fusion begins
A
Each of the following lists two statements. Which two are the basic premises for the special theory of relativity? A) 1. The laws of nature are the same for everyone. 2. The speed of light is the same for everyone. B) 1. The laws of nature are the same for everyone. 2. Everything is relative. C) 1. The speed of light is the same for everyone. 2. You can't go faster than the speed of light. D) 1. Everything is relative. 2. You can never really tell who is moving. E) 1. You can't go faster than the speed of light. 2. Time is different for different people.
A
From a theoretical standpoint, what is a pulsar? A) a rapidly rotating neutron star B) a binary system that happens to be aligned so that one star periodically eclipses the other C) a neutron star or black hole that happens to be in a binary system D) a star that is burning iron in its core E) a star that alternately expands and contracts in size
A
How does the gravity of an object affect light? A) Light coming from a compact massive object, such as a neutron star, will be redshifted. B) Less energetic light will not be able to escape from a compact massive object, such as a neutron star, but more energetic light will be able to. C) Light doesn't have mass; therefore, it is not affected by gravity. D) Visible light coming from a compact massive object, such as a neutron star, will be redshifted, but higher frequencies such as X rays and gamma rays will not be affected. E) Light coming from a compact massive object, such as a neutron star, will be blueshifted.
A
If you draw a spacetime diagram, the worldline of an object that is stationary in your reference frame is A) vertical. B) horizontal. C) slanted. D) curved. E) a circle.
A
Protons and neutrons A) are composed of the same number of quarks. B) have exactly the same charge. C) have exactly the same mass. D) are leptons. E) are fundamental particles
A
Quantum mechanics is A) a branch of physics that applies on very small scales. B) a branch of physics that deals with the curvature of spacetime. C) the idea that mechanics can be understood only if we first understand quantums. D) a branch of physics that deals with the properties of gases. E) the idea that quantitative methods are needed to understand physics.
A
Since all stars begin their lives with the same basic composition, what characteristic most determines how they will differ? A) mass they are formed with B) luminosity they are formed with C) location where they are formed D) time they are formed E) color they are formed with
A
Suppose you see two main-sequence stars of the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude? (Neglect any effects that might be caused by interstellar dust and gas.) A) Star 1 is 10 times more distant than Star 2. B) Star 1 is 100 times nearer than Star 2. C) The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2. D) Star 1 is 100 times more distant than Star 2. E) Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.
A
The characteristic that distinguishes fermions from bosons is A) their spin. B) their speed of travel. C) their size. D) their mass. E) their electric charge.
A
What do astronomers mean when they say that we are all "star stuff"? A) that the carbon, oxygen, and many elements essential to life were created by nucleosynthesis in stellar cores B) that the Universe contains billions of stars C) that the Sun formed from the interstellar medium: the "stuff" between the stars D) that Earth formed at the same time as the Sun E) that life would be impossible without energy from the Sun
A
What evidence supports the predicted existence of gravitational waves? A) The orbit of a star system consisting of two neutron stars is slowly decaying, suggesting that energy is being carried away by gravitational waves. B) Gravitational waves are frequently and easily detected by large telescopes. C) The energy generated by gravitational waves from the Sun can be seen as it is absorbed by Jupiter. D) Gravitational waves have been detected by observing their effect on large masses suspended on Earth. E) Photographs of spacetime show the gravitational waves as ripples that are clearly visible.
A
What happens when a star exhausts its core hydrogen supply? A) Its core contracts, but its outer layers expand and the star becomes bigger and brighter. B) It expands, becoming bigger but dimmer. C) It contracts, becoming hotter and brighter. D) Its core contracts, but its outer layers expand and the star becomes bigger but cooler and therefore remains at the same brightness. E) It contracts, becoming smaller and dimmer.
A
Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusion or fission? A) iron B) hydrogen C) silicon D) uranium E) oxygen
A
Which of the following is closest in size (radius) to a neutron star? A) a city B) a basketball C) the Sun D) a football stadium E) Earth
A
You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two? A) The line in the faster rotating star is broader. B) The line in the faster rotating star is redshifted. C) There is no difference. D) The line in the faster rotating star is narrower. E) The line in the faster rotating star is blueshifted.
A
After a massive-star supernova, what is left behind? A) always a white dwarf B) either a neutron star or a black hole C) always a neutron star D) either a white dwarf or a neutron star E) always a black hole
B
Approximately, what basic composition are all stars born with? A) half hydrogen, half helium, no more than 2 percent heavier elements B) three-quarters hydrogen, one-quarter helium, no more than 2 percent heavier elements C) 90 percent hydrogen, 10 percent helium, no more than 1 percent heavier elements D) one-quarter hydrogen, three-quarters helium, no more than 2 percent heavier elements E) 98 percent hydrogen, 2 percent helium
B
Compared to the star it evolved from, a red giant is A) hotter and brighter. B) cooler and brighter. C) hotter and dimmer. D) cooler and dimmer. E) the same temperature and brightness.
B
How are wavelength, frequency, and energy related for photons of light? A) There is no simple relationship because different photons travel at different speeds. B) Longer wavelength means lower frequency and lower energy. C) Longer wavelength means lower frequency and higher energy. D) Longer wavelength means higher frequency and higher energy. E) Longer wavelength means higher frequency and lower energy.
B
How does the explosion of a nuclear bomb provide evidence of the theory of relativity? A) The mass of the bomb when it explodes is much greater than its normal mass. B) The bomb produces energy in accord with E = mc2, which is part of the theory of relativity. C) The bomb shortens the lifetimes of all people who happen to be near it when it detonates. D) The bomb causes things in its vicin
B
On a Hertzsprung-Russell diagram, where would we find stars that are cool and dim? A) upper right B) lower right C) upper left D) lower left
B
The four fundamental forces are A) nuclear force, gravity, tidal force, magnetic force. B) strong force, weak force, electromagnetic force, gravity. C) strong force, weak force, electric force, magnetic force. D) nuclear force, electromagnetic force, gravity, tidal force.
B
The spectra of most galaxies show redshifts. This means that their spectral lines A) have wavelengths that are shorter than normal. B) have wavelengths that are longer than normal. C) have normal wavelengths, but absorption of light makes them appear red. D) have a higher intensity in the red part of the spectrum. E) always are in the red part of the visible spectrum.
B
The two fundamental laws that lie at the heart of quantum mechanics are A) the law of conservation of angular momentum and the law of conservation of energy. B) the uncertainty principle and the exclusion principle. C) the law of quantum degeneracy and the law of inviolate absolutes. D) the law of conservation of energy and the electromagnetic force law. E) the absoluteness of the speed of light and the equivalence principle.
B
What do we mean by dimension in the context of relativity? A) the height of an object B) the number of independent directions in which movement is possible C) the number of sides that we can see when we look at an object D) the letter used to represent length mathematically E) the size of an object
B
What do we mean when we say that the Sun is in gravitational equilibrium? A) The Sun always has the same amount of mass, creating the same gravitational force. B) There is a balance within the Sun between the outward push of pressure and the inward pull of gravity. C) The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward. D) This is another way of stating that the Sun generates energy by nuclear fusion. E) The Sun maintains a steady temperature.
B
What happens to the rotation of a molecular cloud as it collapses to form a star? A) The rotation rate increases and results in fast rotation of the star. B) The rotation rate increases and results in a disk of material around a protostar. C) The rotation rate remains the same and results in stellar rotation. D) The rotation dissipates and any residual is left in small overall rotation of the star. E) The rotation increases the speed of collapse and produces more massive stars.
B
What happens when the gravity of a massive star is able to overcome neutron degeneracy pressure? A) The core contracts and becomes a ball of neutrons. B) The core contracts and becomes a black hole. C) The star explodes violently, leaving nothing behind. D) Gravity is not able to overcome neutron degeneracy pressure. E) The core contracts and becomes a white dwarf
B
What types of stars end their lives with supernovae? A) stars that are similar in mass to the Sun B) stars that are at least several times the mass of the Sun C) stars that have reached an age of 10 billion years D) all stars that are yellow in color E) all stars that are red in color
B
When an electron in an atom goes from a higher energy state to a lower energy state, the atom A) absorbs several photons of a specific frequency. B) emits a photon of a specific frequency. C) can absorb a photon of any frequency. D) absorbs a photon of a specific frequency E) can emit a photon of any frequency
B
When does a protostar become a true star? A) when the star is 1 million years old B) when nuclear fusion begins in the core C) when the thermal energy becomes trapped in the center D) when the stellar winds and jets blow away the surrounding material E) when the central temperature reaches 1 million Kelvin
B
When does a star become a main-sequence star? A) when hydrogen fusion is occurring throughout a star's interior B) when the rate of hydrogen fusion within the star's core is high enough to maintain gravitational equilibrium C) when the protostar assembles from a molecular cloud D) the instant when hydrogen fusion first begins in the star's core E) when a star becomes luminous enough to emit thermal radiation
B
Which of the following sequences correctly describes the stages of life for a low-mass star? A) white dwarf, main-sequence, red giant, protostar B) protostar, main-sequence, red giant, white dwarf C) protostar, main-sequence, white dwarf, red giant D) protostar, red giant, main-sequence, white dwarf E) red giant, protostar, main-sequence, white dwarf
B
Which of the following statements about neutrinos is not true? A) Neutrinos are neither attracted nor repelled by electrically charged particles. B) Neutrinos do not respond to the force of gravity. C) Neutrinos have a mass that is much smaller than the mass of an electron. D) There are three types of neutrinos, and these represent three of the six known types of lepton. E) Neutrinos do not respond to the strong nuclear force.
B
Which of the following statements best describes the exclusion principle? A) The laws of quantum mechanics are excluded from our common sense. B) Two fermions cannot occupy the same quantum state at the same time. C) Two photons cannot be in the same place at the same time. D) The laws of quantum mechanics are excluded from applying to large objects made of many atoms. E) If a particle has a precisely defined position, it is excluded from having a precisely defined momentum.
B
Which two energy sources can help a star maintain its internal thermal pressure? A) chemical reactions and gravitational contraction B) nuclear fusion and gravitational contraction C) nuclear fusion and nuclear fission D) nuclear fission and gravitational contraction E) nuclear fusion and chemical reactions
B
Why do scientists think that our solar system must have formed sometime after nearby supernovae explosions? A) Our Sun is a G-type star B) Existence of heavy elements C) Solar temperature too low D) They don't scientists believe our Sun is among the first generation of stars.
B
You observe a star in the disk of the Milky Way, and you want to plot the star on an H-R diagram. You will need to determine all of the following, except the A) spectral type of the star. B) rotation rate of the star. C) distance to the star. D) apparent brightness of the star in our sky.
B
A spaceship is headed toward Alpha Centauri at 0.999c. According to us, the distance to Alpha Centauri is about 4 light-years. How far away is Alpha Centauri according to the travelers in the ship? A) quite a bit more than 4 light-years B) very slightly more than 4 light-years C) quite a bit less than 4 light-years D) also about 4 light-years E) very slightly less than 4 light-years
C
According to general relativity, a black hole is A) a place where there is no gravity. B) a place where light travels faster than the normal speed of light. C) a hole in the observable universe. D) a place where light travels slower than the normal speed of light. E) an object that cannot be seen.
C
Al is moving by you at a very high speed (close to the speed of light). You get out a clock and measure 10 seconds going by. If you also watch a clock in Al's ship, how much time will you see it record during your 10 seconds? A) Al's clock will agree that 10 seconds go by. B) Al's clock will record more than 10 seconds. C) Al's clock will record less than 10 seconds
C
From the center outward, which of the following lists the "layers" of the Sun in the correct order? A) core, convection zone, radiation zone, corona, chromosphere, photosphere B) core, radiation zone, convection zone, corona, chromosphere, photosphere C) core, radiation zone, convection zone, photosphere, chromosphere, corona D) core, corona, radiation zone, convection zone, photosphere, chromosphere E) core, convection zone, radiation zone, photosphere, chromosphere, corona
C
If we could measure the mass of the spaceship as it goes by, what would it be? A) Its mass is infinite. B) Its mass is less than its rest mass. C) Its mass is greater than its rest mass. D) Its mass is the same as it would be if it were not moving.
C
Jackie is floating freely in her spacecraft, and you are accelerating away from her with an acceleration of 1g. How will you feel in your spacecraft? A) You will be floating weightlessly. B) You will feel weight, but less than on Earth. C) You will feel the same weight as you do on Earth. D) You will feel weight, but more than on Earth. E) You will feel yourself pressed against the back of your spaceship with great force, making it difficult to move.
C
Observationally, how can we tell the difference between a white-dwarf supernova and a massive-star supernova? A) The spectrum of a massive-star supernova shows prominent hydrogen lines, while the spectrum of a white-dwarf supernova does not. B) A massive-star supernova happens only once, while a white-dwarf supernova can repeat periodically. C) The light of a white-dwarf supernova fades steadily, while the light of a massive-star supernova brightens for many weeks. D) A massive-star supernova is brighter than a white-dwarf supernova. E) We cannot yet tell the difference between a massive-star supernova and a white-dwarf supernova.
C
Suppose two lines appear to be parallel but eventually meet. What type of geometry are you dealing with? A) This situation can never occur. B) flat geometry C) spherical geometry D) saddle-shaped geometry E) Euclidean geometry
C
Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.) A) The red star has a hotter surface temperature than the blue star. B) The red star is more massive than the blue star. C) The blue star has a hotter surface temperature than the red star. D) The blue star is farther away than the red star. E) The blue star is more massive than the red star
C
The primary purpose of a particle accelerator is to A) make small particles go very fast. B) produce energy for commercial use. C) create particles and study their behavior. D) test new ideas about the law of gravity. E) make small particles achieve large accelerations.
C
The two families of fundamental particles out of which all ordinary matter is made are A) quarks and neutrinos. B) leptons and photons. C) leptons and quarks. D) protons and neutrons. E) electrons and neutrinos.
C
What does the equivalence principle say? A) You cannot distinguish between motion at constant velocity and weight in a gravitational field. B) All observers must always measure the same (equivalent) weights for moving objects. C) The effects of gravity are exactly equivalent to the effects of acceleration. D) Gravity is the same thing as curvature of spacetime. E) The effects of relativity are exactly equivalent to those predicted by Newton's laws of motion.
C
What happens to the visible radiation produced by new stars within a molecular cloud? A) The blue light is absorbed and the red light transmitted. B) It is reflected back onto the protostar, heating it up further. C) It is absorbed by dust grains and heats up the cloud. D) It escapes the cloud completely. E) It shoots out in bright jets.
C
What is the basic definition of a black hole? A) any object made from dark matter B) a dead star that has faded from view C) any object from which the escape velocity exceeds the speed of light D) any compact mass that emits no light E) a dead galactic nucleus that can only be viewed in infrared
C
What is the eventual fate of a brown dwarf? A) It gradually contracts and heats up until nuclear fusion ignites in its interior and it becomes a faint star. B) Gravity ultimately "wins" and it becomes a small black hole. C) It gradually cools down and becomes ever dimmer. D) It remains the same forever. E) It becomes ever denser and hotter until it becomes a white dwarf.
C
Where would a brown dwarf be located on an H-R diagram? A) above and to the left of the main sequence B) on the lower part of the main sequence C) below and to the right of the lowest part of the main sequence D) lower left E) upper right
C
Which layer of the Sun do we normally see? A) chromosphere B) radiation zone C) photosphere D) corona E) convection zone
C
Which of the following is not a prediction made by the theory of relativity? A) No material object sent outward from Earth can reach or exceed the speed of light. B) E = mc2 C) Observers in different reference frames may disagree about the basic laws of nature. D) Observers in different reference frames may disagree about whether two events in two different places occur simultaneously. E) Observers in different reference frames may disagree about the time and distance between two events.
C
Which of the following statements about black holes is not true? A) If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls nearer to the black hole. B) If you watch someone else fall into a black hole, you will never see him or her cross the event horizon. However, he or she will fade from view as the light he or she emits (or reflects) becomes more and more redshifted. C) If the Sun magically disappeared and was replaced by a black hole of the same mass, Earth would soon be sucked into the black hole. D) A black hole is truly a hole in spacetime, through which we could leave the observable universe. E) If you fell into a black hole, you would experience time to be running normally as you plunged rapidly across the event horizon.
C
Which of the following statements about novae is not true? A) When a star system undergoes a nova, it brightens considerably, but not as much as a star system undergoing a supernova. B) A nova involves fusion taking place on the surface of a white dwarf. C) Our Sun will probably undergo at least one nova when it becomes a white dwarf about 5 billion years from now. D) A star system that undergoes a nova may have another nova sometime in the future. E) The word nova means "new star" and originally referred to stars that suddenly appeared in the sky, then disappeared again after a few weeks or months.
C
Which statement best describes the solar neutrino problem? A) The term solar neutrino problem refers to the fact that neutrinos are extremely difficult to detect. B) Theoretical models predict that neutrinos should be produced in the Sun, but no neutrinos have ever been observed to be coming from the Sun. C) Solar neutrinos have been detected, but in fewer numbers than predicted by theoretical models. D) No one understands how it can be possible for neutrinos to be produced in the Sun. E) Our current understanding of fusion in the Sun suggests that all neutrinos should be destroyed before they arrive at Earth, yet neutrinos are being detected.
C
A star's luminosity is the A) lifetime of the star. B) surface temperature of the star. C) total amount of light that the star will radiate over its entire lifetime. D) total amount of light that the star radiates each second. E) apparent brightness of the star in our sky
D
All of the following are involved in carrying energy outward from a star's core except A) convection. B) neutrinos. C) radiative diffusion. D) conduction.
D
Bob is coming toward you at a speed of 75 km/hr. You throw a baseball in his direction at 75 km/hr. What does he see the ball doing? A) He sees the ball coming at him at 75 km/hr. B) He sees the ball going away from him at 150 km/hr. C) He sees the ball going away from him at 75 km/hr. D) He sees the ball coming at him at 150 km/hr. E) He sees the ball remaining stationary.
D
From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation? A) infrared, visible light, ultraviolet, X rays, gamma rays, radio B) gamma rays, X rays, visible light, ultraviolet, infrared, radio C) visible light, infrared, X rays, ultraviolet, gamma rays, radio D) gamma rays, X rays, ultraviolet, visible light, infrared, radio E) radio, infrared, visible light, ultraviolet, X rays, gamma rays
D
How would we view time (clocks) on the spaceship as it goes by? A) Their clocks are going faster than ours. B) Their clocks are going exactly half as fast as ours. C) Time is the same for everyone. D) Their clocks are going slower than ours. E) Their clocks are going at the same rate as ours
D
If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits A) 12 times more energy. B) 3 times more energy. C) 9 times more energy. D) 81 times more energy. E) none of the above
D
If you draw a spacetime diagram, the worldline of an object that is accelerating away from you is A) vertical. B) horizontal. C) slanted. D) curved. E) a circle.
D
In relativity, two people share the same frame of reference only if A) they agree on the laws of nature. B) they are both located in the same place. C) they are both located in the same place and are stationary. D) they are not moving relative to each other. E) they are both located in the same place and are traveling at the same speed.
D
Suppose that, through the malicious act of an eight-dimensional alien being, the strong force was suddenly turned off throughout the universe. What would happen almost immediately to atoms? A) Electrons would fall into the nuclei of atoms. B) Atoms would be immediately ionized. C) nothing D) The nuclei of atoms would fall apart. E) Gravity would become the strongest force in nature.
D
Suppose you put two protons near each other. Because of the electromagnetic force, the two protons will A) collide. B) join together to form a nucleus. C) remain stationary. D) repel each other. E) attract each other.
D
The helium fusion process results in the production of A) nitrogen. B) iron. C) oxygen. D) carbon. E) hydrogen
D
The most abundant molecule in molecular clouds is A) He2. B) HHe. C) CO. D) H2. E) H2O.
D
The spectral sequence in order of decreasing temperature is A) OFBAGKM. B) OBAGFKM. C) BAGFKMO. D) OBAFGKM. E) ABFGKMO.
D
What is a planetary nebula? A) the expanding shell of gas that is left when a white dwarf explodes as a supernova B) the molecular cloud from which protostars form C) a disk of gas surrounding a protostar that may form into planets D) the expanding shell of gas that is no longer gravitationally held to the remnant of a low-mass star E) what is left of the planets around a star after a low-mass star has ended its life
D
Which of the following statements about an open cluster is true? A) All stars in the cluster are approximately the same color. B) There is an approximately equal number of all types of stars in the cluster. C) All stars in the cluster will evolve similarly. D) All stars in the cluster are approximately the same age. E) All stars in the cluster have approximately the same mass
D
Which of the following statements about thermal radiation is always true? A) A hot object emits photons with a longer wavelength than a cool object. B) A hot object emits more radio waves than a cool object. C) A hot object emits more X rays than a cool object. D) A hot object emits photons with a higher average energy than a cool object.
D
Why are neutrinos so difficult to detect? A) because they are so small B) because they have no mass C) because they move at nearly the speed of light D) because they rarely interact with matter E) because there are so rare
D
Why do sunspots appear dark in pictures of the Sun? A) They emit light in other wavelengths that we can't see. B) They are holes in the solar surface through which we can see to deeper, darker layers of the Sun. C) They are too cold to emit any visible light. D) They actually are fairly bright but appear dark against the even brighter background of the surrounding Sun. E) They are tiny black holes, absorbing all light that hits them.
D
You discover a binary star system in which one member is a15MSun main-sequence star and the other star is a 10MSun giant. How do we believe that a star system such as this might have come to exist? A) The main-sequence star probably is a pulsating variable star and therefore appears to be less massive than it really is. B) Despite the low odds of finding a system with two such massive stars, there is nothing surprising about the fact that such systems exist. C) The two stars probably were once separate but became a binary when a close encounter allowed their mutual gravity to pull them together. D) The giant must once have been the more massive star but transferred some of its mass to its companion. E) Although both stars probably formed from the same clump of gas, the more massive one must have had its birth slowed so that it became a main-sequence star millions of years later than its less massive companion.
D
You take a trip to a star located 1,000 light-years away and return. You travel at an average speed of 0.99c. The predictions of special relativity can sound implausible at first. What observational evidence do scientists have that the theory is correct? (Picture) A) Time dilation can be observed in airplanes. B) Subatomic particles in accelerators exhibit effects of time dilation and mass increase at high speeds. C) Light is always observed to travel at the same speed. D) All of the above
D
According to general relativity, how is time affected by gravity? A) Time is not affected by gravity. B) Time is stopped by any gravitational field. C) Time runs faster in stronger gravitational fields. D) Time is affected by gravity, but not in a predictable way. E) Time runs slower in stronger gravitational fields
E
After a supernova event, what is left behind? A) always a neutron star B) either a white dwarf or a neutron star C) always a black hole D) always a white dwarf E) either a neutron star or a black hole
E
From an observational standpoint, what is a pulsar? A) a star that slowly changes its brightness, getting dimmer and then brighter with a period of anywhere from a few hours to a few weeks B) a star that changes color rapidly, from blue to red and back again C) an object that emits random "pulses" of light that sometimes occur only a fraction of a second apart and other times stop for several days at a time D) a star that rapidly changes size as it moves off the main sequence E) an object that emits flashes of light several times per second or more, with near perfect regularity
E
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude? A) The star is getting hotter. B) The star is moving away from us. C) The "star" actually is a planet. D) The star is getting colder. E) The star is moving toward us
E
How does the Sun generate energy today? A) gradually expanding in size B) gravitational contraction C) nuclear fission D) chemical reactions E) nuclear fusion
E
If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects? A) The one with the large redshift is redder than the other one. B) The one with the large redshift is moving toward us faster than the one with the small redshift. C) The one with the large redshift is hotter and therefore is putting out more radiation. D) The one with the large redshift is moving away from us, and the one with the small redshift is moving toward us. E) The one with the large redshift is moving away from us faster than the one with the small redshift.
E
On the main sequence, stars obtain their energy A) from chemical reactions. B) from gravitational contraction. C) from nuclear fission. D) by converting helium to carbon, nitrogen, and oxygen. E) by converting hydrogen to helium.
E
The most distant stars we can measure stellar parallax for are approximately A) 50 parsecs away. B) in the Andromeda Galaxy. C) 5,000 parsecs away. D) halfway across the Milky Way Galaxy. E) 100 parsecs away.
E
What is interstellar reddening? A) The spectral line shift due to a star's motion through the interstellar medium. B) Interstellar dust absorbs more red light than blue light, making stars appear bluer than their true color. C) Interstellar dust absorbs more blue light than red light, making stars appear bluer than their true color. D) Interstellar dust absorbs more red light than blue light, making stars appear redder than their true color. E) Interstellar dust absorbs more blue light than red light, making stars appear redder than their true color.
E
What is the approximate composition of the Sun? A) 98 percent hydrogen, 2 percent helium and other elements B) 100 percent hydrogen and helium C) 70 percent helium, 28 percent hydrogen, 2 percent other elements D) 50 percent hydrogen, 25 percent helium, 25 percent other elements E) 70 percent hydrogen, 28 percent helium, 2 percent other elements
E
What is the average temperature of the surface of the Sun? A) 1 million K B) 100,000 K C) 1,000 K D) 10,000 K E) 6,000 K
E
What is the smallest mass a newborn star can have? A) about 1/800 the mass of our Sun B) 800 times the mass of Jupiter C) 8 times the mass of Jupiter D) about 1/80 the mass of our Sun E) 80 times the mass of Jupiter
E
What is the ultimate fate of an isolated white dwarf? A) As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova. B) As gravity overwhelms the electron degeneracy pressure, it will explode as a nova. C) As gravity overwhelms the electron degeneracy pressure, it will become a neutron star. D) The electron degeneracy pressure will eventually overwhelm gravity and the white dwarf will slowly evaporate. E) It will cool down and become a cold black dwarf.
E
What is the upper limit to the mass of a white dwarf? A) There is no upper limit. B) 1 solar mass C) 2 solar masses D) There is an upper limit, but we do not yet know what it is. E) 1.4 solar masses
E
Which of the following is closest in size (radius) to a white dwarf? A) a small city B) a basketball C) a football stadium D) the Sun E) Earth
E
Which of the following statements is not a prediction of the general theory of relativity? A) The curvature of spacetime can distort the appearance of distant objects. B) Time runs slightly slower on the surface of the Sun than on the surface of Earth. C) A binary star system with two stars orbiting each other rapidly emits gravitational waves. D) The Universe has no boundaries and no center. E) Different observers can disagree about the fundamental structure of spacetime
E
White dwarfs are so called because A) they are the opposite of black holes. B) it amplifies the contrast with red giants. C) they are supported by electron degeneracy pressure. D) they are the end-products of small, low-mass stars. E) they are both very hot and very small.
E
Why is there an upper limit to the mass of a white dwarf? A) The upper limit to the masses of white dwarfs was determined through observations of white dwarfs, but no one knows why the limit exists. B) White dwarfs come only from stars smaller than 1.4 solar masses. C) Above this mass, the electrons would be pushed together so closely they would turn into neutrons and the star would become a neutron star. D) The more massive the white dwarf, the higher its temperature and hence the greater its degeneracy pressure. At about 1.4 solar masses, the temperature becomes so high that all matter effectively melts, even individual subatomic particles. E) The more massive the white dwarf, the greater the degeneracy pressure and the faster the speeds of its electrons. Near 1.4 solar masses, the speeds of the electrons approach the speed of light, so more mass cannot be added without breaking the degeneracy pressure
E
