ASTR 103 Exam 3
By approximately how many degrees Celsius has the average global temperature increased in the last 100 years?
1 degree
Heavier elements require higher temperatures to fuse. After stars run out of hydrogen in their cores, they leave the main sequence, collapse, and eventually get hot enough to fuse the helium in their cores into carbon. As discussed in the previous chapter, the Sun will never get hot enough to fuse carbon. Which of these hypothetical situations would allow the temperature of the Sun's core to rise enough for carbon fusion to be possible? Choose one: A. Add mass to the Sun. B. Increase the radius of the Sun. C. Convert all of the Sun's hydrogen into carbon. D. Decrease the radius of the Sun.
a
How do protons ever fuse together in the presence of the electromagnetic force? There is another force involved here called the nuclear strong force. It is the strongest of all the forces, but it only acts over extremely small distances before it becomes too weak to matter. If protons and neutrons are able to get close enough to one another, the strong force provides a powerful attractive force that can bind them together in a nucleus, despite the electromagnetic force. Watch this animation, and then choose the condition that would make it more likely for two nuclei to fuse together. Choose one: A. The nuclei are moving fast with respect to one another. B. The nuclei are very massive. C. The nuclei have opposite charges. D. The nuclei are moving slowly with respect to one another.
a
The huge amount of energy released in supernova explosions is strong enough to fuse nuclei together into elements heavier than iron. Because these elements cannot be created in ordinary stellar nuclear fusion, supernovae are the only natural source of them in the universe. Locate a periodic table of the elements such as the one in your book, and use it to determine which of the following elements are produced only in supernova explosions. Choose one or more: A. nitrogen B. copper C. gold D. iron E. calcium F. silver G. aluminum H. helium
b c f
A neutron star is Choose one: A. always a pulsar. They are the same thing. B. full of protons. C. imaginary. D. left over from the death of a massive star.
d
In chemistry, a catalyst is a reaction helper. It facilitates the reaction but does not get used up in the process. Are there any nuclei that act like catalysts in the proton-proton chain? Choose one: A. Two positrons are catalysts. B. Two neutrinos are catalysts. C. Two gamma rays are catalysts. D. Two of the hydrogen nuclei are catalysts.
d
Stars begin burning helium to carbon when the temperature rises in the core. This temperature increase is caused by Choose one: A. fusion of hydrogen into helium in the core. B. electron degeneracy pressure. C. fusion of hydrogen into helium in a shell around the core. D. gravitational collapse.
d
How does mass determine the main-sequence lifetime of a star? Choose one: A. More massive stars burn fuel faster than low-mass stars and thus have shorter lives. B. More massive stars burn different fuels than low-mass stars and thus have longer lives. C. More massive stars have more fuel than low-mass stars and thus have longer lives. D. More massive stars have different initial compositions than low-mass stars and thus have shorter lives.
a
If we experience a year that is much hotter than the previous year, this means that Earth is going through a global warming trend, where the temperature will now continually increase each year. Choose one: A. It is impossible to tell with one year of data. B. true C. false
a
In the proton-proton chain, four hydrogen nuclei are converted to a helium nucleus. This does not happen spontaneously on Earth because the process requires Choose one: A. very high temperatures and pressures. B. vast amounts of hydrogen. C. very strong magnetic fields. D. hydrostatic equilibrium.
a
It is rare to see a helium flash because Choose one: A. the flash does not take very long. B. few stars go through this stage. C. stars that go through this stage are all far away. D. the flash is not very bright.
a
Ordinarily, the hotter an object is, the more luminous it is. In this case, the temperature has gone down, but the luminosity has gone up. How can this be? Choose one: A. The radius is larger. B. The radius is smaller.
a
The article refers to the white dwarfs in the study as "hot, young, white dwarfs." What does "young" mean in this context? Choose one: A. These white dwarfs were recently formed after the collapse of a low-mass star. B. These white dwarfs were formed as companions to young, Sun-like stars. C. These white dwarfs were formed within the past decade. D. These white dwarfs formed just after the Big Bang.
a
The force of a magnetic field on a stationary charge is Choose one: A. zero. B. circular. C. larger than the force on a moving charge. D. perpendicular to the direction of the magnetic field.
a
Why do the lighter isotopes disappear first from the atmosphere? Where do those isotopes go? Choose one: A. Lighter molecules move fast and escape from the upper atmosphere relatively quickly. B. Lighter molecules move slowly and escape from the upper atmosphere relatively quickly. C. Lighter molecules move slowly and fall to the ground relatively quickly. D. Lighter molecules move fast and fall to the ground relatively quickly.
a
Why does Mars have such a low surface pressure? Visit the AstroTour "Atmospheres: Formation and Escape" on how planets gain and lose atmospheres. Then choose the statement that corresponds to the biggest factor that resulted in Mars having a thinner atmosphere than Earth and Venus. Choose one: A. Mars is less massive than Earth and Venus. B. Mars has a longer year than Earth and Venus. C. Mars had fewer comet impacts than Earth and Venus. D. Mars is farther away from the Sun than Earth and Venus.
a
Compare the atmospheric properties of the planets in the table to the right. The surface temperature is the average for the entire planet in units of Kelvin (subtract 273 from that number to convert it into units of Celsius). The surface pressure is related to how thick the atmosphere is (thicker atmospheres have more air molecules packed into the same volume, and thus higher pressure). Given the information in this table, how would you explain the difference in greenhouse effect strength for each of the planets? Choose one or more: A. Venus has a very strong greenhouse effect because it has a high percentage of carbon dioxide in its atmosphere and also a high surface pressure. B. Mars has a weak greenhouse effect because it has very low surface pressure. C. Earth has a much higher percentage of nitrogen in its atmosphere, causing it to have a stronger greenhouse effect than Venus and Mars. D. Venus and Mars both have a very high percentage of carbon dioxide in their atmospheres, creating a stronger greenhouse effect than Earth's atmosphere, which has very little. E. Planets that are closer to the Sun will have a stronger greenhouse effect than those farther away from the Sun.
a b
How does the energy production in a high-mass, main-sequence star differ from energy production in the Sun? Choose one or more: A. High-mass stars use carbon in a process that fuses hydrogen to helium. B. High-mass stars produce energy at a faster rate. C. High-mass stars burn carbon on the main sequence. D. High-mass stars get a lot of energy through non-nuclear processes.
a b
Why might it be difficult to drop a probe into the Great Red Spot? Choose one or more: A. The storm has very high pressure. B. The storm has very high wind speeds. C. The storm is moving too fast around the planet. D. The storm has a very cold temperature.
a b
Why does Mercury have so little gas in its atmosphere? A. Its escape velocity is low. B. It is close to the Sun. C. Its mass is small. D. It has a high temperature. E. It has no moons.
a b c d
All Type Ia supernovae Choose one or more: A. always involve a white dwarf. B. always release the same amount of energy in fusion. C. involve degenerate matter. D. are at the same distance from Earth.
a c
Over the past 800,000 years, ice-core data indicate which of the following are correlated? Choose one or more: A. CH4 levels B. the size of the ozone hole C. CO2 levels D. temperature
a c d
Jupiter and Saturn, despite being considerably farther from us than the inner terrestrial planets, are very bright in our sky. Which of the following choices are possible explanations for this? Choose one or more: A. They are more reflective (higher albedo) than most of the terrestrial planets. B. Dust obscures our view of the inner planets more than the outer ones. C. Since they are closer to stars, more starlight is reflected off of them than the inner planets. D. They are larger than the terrestrial planets. E. They are so hot that they emit blackbody radiation that peaks in the visible.
a e
A white dwarf will become a supernova if Choose one: A. the original star was more than 1.38 MSun. B. enough mass accretes from a companion to give the white dwarf a total mass of 1.38 MSun. C. even a small amount of mass falls on it from a companion. D. it accretes an additional 1.38 MSun from a companion.
b
An AGB star expands to a much larger size (rAGB) than it did during the red giant phase for our Sun. Recall that the force of gravity between two objects is given by this equation, where m1 and m2 are the masses, and r is the distance between them: F=Gm1m2r2F=Gm1m2r2. How will the gravitational force on a piece of the surface of the star (m1) by the mass of the rest of the star (m2) (effectively located at a point at the center of the star) compare between the AGB and main-sequence phases of a particular star, assuming its mass stays the same? Choose one: A. The surface will feel a stronger gravitational force during the AGB phase because the star is larger. B. The surface will feel a weaker gravitational force during the AGB phase because it is farther from the center of the star. C. The surface will feel the same gravitational force during both phases.
b
How does the solar minimum that occurred around 2008 compare to those in the previous solar cycles? Choose one: A. It lasted for a shorter period of time. B. It lasted for a longer period of time. C. It was exactly the same, since the solar cycle is periodic. D. There were more sunspots.
b
If 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 young. C. very old. D. very hot.
b
If we were to take a snapshot of where the photons are inside the Sun, and which direction they are traveling, we would find that Choose one: A. all the photons are traveling directly inward, toward the center. B. photons are traveling in all directions. C. half are traveling directly outward, but half are traveling directly inward. D. all the photons are traveling directly outward, toward the surface.
b
In Latin, nova means "new." This word is used for novae and supernovae because they are newly Choose one: A. dead stars. B. visible stars. C. formed stars. D. expanded stars.
b
In a white dwarf, electrons are packed in so tightly that they physically cannot get any closer to one another. This provides an overall outward force, similar to the white dwarf's thermal pressure but much stronger, called electron degeneracy pressure, which does not depend on the temperature of the material. A white dwarf no longer has any ongoing energy production from nuclear fusion, so it will continuously cool off with time. Taking into consideration all the forces acting on each piece of the white dwarf, what will happen to it as it cools? Choose one: A. It will become variable as it periodically expands and collapses. B. It will stay constant in size. C. It will expand. D. It will collapse eventually into a singularity (a point).
b
Neptune's existence was predicted because Choose one: A. Uranus became brighter and fainter in an unusual way. B. Uranus did not obey Newton's laws of motion. C. some of the solar nebula's mass was unaccounted for. D. Uranus wobbled on its axis.
b
The article describes two different isotopes of water: regular water and semi-heavy water. What makes the semi-heavy water molecule more massive than a regular water molecule? Choose one: A. The molecule contains one more hydrogen atom. B. The molecule contains an extra neutron in one of the hydrogen atoms. C. The surface gravity of Mars is larger than Earth's. D. The molecule contains two oxygen atoms.
b
The interiors of the giant planets are heated by gravitational contraction. We know this because Choose one: A. the giant planets have strong magnetic fields. B. the giant planets radiate more energy than they receive from the Sun. C. the cores are very hot. D. the giant planets are mostly atmosphere.
b
The ozone layer protects life on Earth from Choose one: A. charged particles trapped in Earth's magnetic field. B. ultraviolet radiation. C. high-energy particles from the solar wind. D. micrometeorites.
b
There is a particle produced in the Sun's nuclear reactions that we can use to directly study what is happening in the interior. Neutrinos are weakly interacting particles, and they have almost no mass and no charge. They are not affected at all by the nuclear strong force. As neutrinos travel through the Sun's dense interior, how will their path change due to the presence of the gravitational, electromagnetic, and nuclear strong forces around them? Choose one: A. They will be attracted to protons and repelled by electrons. B. They will not change at all. C. They will be repelled by protons and attracted to electrons. D. They will be bound to nuclei if they get close enough. E. Gravity will pull them toward the center of the Sun.
b
Uranus and Neptune are different from Jupiter and Saturn in that Uranus and Neptune Choose one: A. have no magnetic field. B. have a higher percentage of ices in their interiors. C. are closer to the Sun. D. have no rings.
b
Uranus's orbit did not appear to behave according to Newton's laws of motion and gravity. The most likely culprit for Uranus's misbehaving orbit was the gravitational influence of another planet. Using Newton's laws, astronomers were able to calculate exactly where they would expect this still-undiscovered planet to be. When telescopes were pointed at this position, Neptune was seen. What does this imply? Choose one: A. Newton's laws have been falsified. B. Newton's laws have been verified by yet another test, so we should use them with high confidence until and unless they are falsified by future tests. C. Newton's laws have been verified by yet another test, but there is still not enough evidence for them, so they should be treated with cautious skepticism. D. Newton's laws have been verified as absolute truth.
b
When the Sun runs out of hydrogen in its core, it will become larger and more luminous because Choose one: A. energy balance no longer holds, and the star just drifts apart. B. it starts fusing hydrogen in a shell around a helium core. C. it starts fusing helium in a shell and hydrogen in the core. D. infalling material rebounds off the core and puffs up the star.
b
When viewed through a telescope, Uranus and Neptune are distinctly bluish green in color. What gas is responsible for this striking appearance? Choose one: A. water B. methane C. hydrogen D. helium
b
The words weather and climate Choose one or more: A. mean essentially the same thing. B. refer to very different time scales. C. refer to very different size scales.
b c
What causes the auroras of the giant planets? Choose one or more: A. strong electrical currents B. charged particles C. strong magnetic fields D. tilted magnetic fields
b c
The first neutrino detector (Homestake, shown in this image) consisted of a 100,000 gallon tank of a chlorine-containing liquid, built 1,500 meters underground to block out particles other than neutrinos that might affect the results. Calculations from the model of the nuclear reactions expected to occur in the Sun predicted that it would detect about 1 neutrino every day as it turned a chlorine atom into argon. In actuality, only 1 neutrino was detected about every 3 days. This was referred to as the solar neutrino problem. What might this problem imply? Choose one or more: A. There may be an extra source of neutrinos that came from a source other than the Sun that the detector was detecting. B. There were fewer neutrinos detected than expected, so something might be wrong with our models. C. There were more neutrinos detected than expected, so something might be wrong with our models. D. The detector may have been missing some neutrinos for some reason. E. Roughly the same number of neutrinos were detected as expected, so our models are likely correct.
b d
A pulsar occurs when a neutron star Choose one: A. has a magnetic axis. B. has a rotation axis. C. has a magnetic axis that is not aligned with the rotation axis. D. has a magnetic axis that is aligned with the rotation axis.
c
A white dwarf is located in the lower left of the H-R diagram. From this information alone, you can determine that it is very Choose one: A. dense. B. massive. C. hot. D. bright.
c
In a high-mass star, hydrogen fusion occurs via the Choose one: A. gravitational collapse. B. proton-proton chain. C. CNO cycle. D. spin-spin interaction.
c
Iron fusion cannot support a star because iron Choose one: A. oxidizes too quickly. B. emits energy when it fuses. C. absorbs energy when it fuses. D. is not dense enough to hold up the layers.
c
Jupiter, Saturn, and Neptune all radiate more energy into space than they receive from the Sun. What is the primary source of the additional energy? Choose one: A. motion of charged particles in their magnetic fields B. radioactive decay of heavy elements C. differentiation of helium from hydrogen in their interiors D. greenhouse gases trapping solar energy
c
Nuclear fusion stops at iron in the core of the star, and the iron ash core collapses under its own gravity. Electron degeneracy pressure stops the core collapse in a low-mass star, but the self-gravity of high-mass stars is large enough to overcome this, and the electrons slam into protons to form neutrons. Like electrons, neutrons are not able to exist within a certain distance of one another. As the core collapses, the neutrons hit this limit in density, and a new, extremely strong outward pressure called neutron degeneracy pressure appears. What effect might this have on the material outside the neutron degenerate core, which was previously collapsing under gravity? Choose one: A. It will continue to collapse at the same rate. B. It will collapse faster. C. It will expand outward.
c
Suppose an abnormally large amount of hydrogen suddenly burned in the core of the Sun. Which of the following would be observed first? Choose one: A. The Sun would become brighter. B. The Sun would become bluer. C. The Sun would emit more neutrinos. D. The Sun would swell and become larger.
c
The image here shows a white dwarf orbiting closely enough around a giant or supergiant star to accrete mass from its companion's outer layers. As material from the outer envelope of the larger star builds up on the surface of the white dwarf, its temperature and density increase continuously. Under this scenario, what is the first event that will eventually happen? Choose one: A. Carbon on the surface of the white dwarf will undergo nuclear fusion. B. The carbon within the entire white dwarf will undergo nuclear fusion. C. Hydrogen on the surface of the white dwarf will undergo nuclear fusion. D. Helium on the surface of the white dwarf will undergo nuclear fusion.
c
The main greenhouse gases in the atmospheres of the terrestrial planets are Choose one: A. methane and ammonia B. oxygen and nitrogen C. carbon dioxide and water vapor D. hydrogen and helium
c
What is the immovable object in a supernova explosion? Choose one: A. the outermost layers of the star B. the intermediate layers of the star C. the innermost core
c
Why does a telescope need to be in space to observe far-ultraviolet wavelengths? Choose one: A. Far-ultraviolet light is so weak that telescopes need to be as close to the source of the light as possible. B. Telescopes must be in space in order to properly detect any type of light. C. Earth's atmosphere blocks far-ultraviolet light from reaching the ground. D. It is better economically to put all telescopes into space.
c
This image shows a low-mass star shedding its outer layer. What happens during this process? Choose one or more: A. Carbon-12 is emitted. B. The star reaches a horizontal branch. C. A planetary nebula is created. D. The star becomes a white dwarf.
c d
A planetary nebula forms from Choose one: A. the remainders of the original star-forming nebula. B. the collapse of the magnetosphere of a high-mass star. C. the collision of planets around a dying star. D. the ejection of mass from a low-mass star.
d
A white dwarf will become a supernova if Choose one: A. it accretes an additional 1.38 MSun from a companion. B. the original star was more than 1.38 MSun. C. some mass falls on it from a companion. D. enough mass accretes from a companion to give the white dwarf a total mass of 1.38 MSun.
d
All weather and wind on Earth are a result of convection in the Choose one: A. mesosphere. B. ionosphere. C. stratosphere. D. troposphere. E. thermosphere.
d
Deep in the interiors of the giant planets, water is still a liquid even though the temperatures are tens of thousands of degrees above the boiling point of water. This can happen because Choose one: A. the density inside the giant planet is so high. B. the outer Solar System is so cold. C. space has very low pressure. D. the pressure inside the giant planet is so high.
d
Elements heavier than iron originated in the Choose one: A. cores of high-mass stars. B. Big Bang. C. cores of low-mass stars. D. explosions of high-mass stars.
d
Go to the NASA press release for this story (http://science.nasa.gov/science-news/science-at-nasa/2014/23jul_superstorm/), and watch the 4-minute "ScienceCast" video. What happened during the Carrington CME in 1859? Choose one: A. Nothing significant, because the people of 1859 did not have any technology that was sensitive to a CME blast. B. Nothing significant, because the CME was too weak to have any measurable effect. C. Electric power was knocked out to homes in a widespread area. D. Telegraph wire sparks caused fires and disrupted communications.
d
Post-main-sequence stars lose up to 50 percent of their mass because Choose one: A. jets from the poles release material at an increasing rate. B. the mass of the star drops because of mass loss from fusion. C. the magnetic field causes increasing numbers of coronal mass ejections. D. the star swells until the surface gravity is too weak to hold material.
d
Sunspots appear dark because Choose one: A. they are regions of very high pressure. B. they have very low density. C. magnetic fields absorb most of the light that falls on them. D. they are cooler than their surroundings.
d
The layers in a high-mass star occur in order of Choose one: A. spin state. B. atomic abundance. C. atomic number. D. fusion temperature.
d
Very young star clusters have main-sequence turnoffs Choose one: A. that drop below the main sequence. B. at the bottom right of the main sequence. C. in the middle of the main sequence. D. at the top left of the main sequence.
d
What causes a high-mass star to explode as a Type II supernova? Choose one: A. The high-mass star merges with another star. B. The high-mass star runs out of mass in the core. C. The CNO cycle uses up all the carbon. D. Iron absorbs energy when it fuses.
d
When the Sun runs out of fuel in its core, the core will be Choose one: A. empty. B. filled with hydrogen. C. filled with carbon. D. filled with helium.
d
When viewed by radio telescopes, Jupiter is the second brightest object in the sky. What is the source of this radiation? Choose one: A. radio waves from the Sun that are reflected by Jupiter B. internal energy produced through helium differentiation C. spacecraft in Jupiter's orbit that are returning data to Earth D. synchrotron radiation from its magnetic field
d
Which of the following best explains why regular water escapes the Martian atmosphere faster than heavy water? Choose one: A. Heavy water bonds more easily with other chemicals, while regular water stays apart. B. Heavy water remains a liquid, while only regular water is a gas. C. The two types of water are mixed evenly in the atmosphere, but the different charge of regular water allows it to be more easily stripped by the Sun's magnetic field. D. Regular water is lighter, so it rises to the top of the atmosphere.
d
Which particle carried away the other positive charge? Choose one: A. neutrino B. gamma ray C. neutron D. positron E. proton
d
Why did Mars lose its ocean of water? Choose one: A. Jupiter came too close and stripped away most of the water from the surface of Mars. B. The planet's climate cooled, and the oceans froze in place. C. A tremendous asteroid impact ejected the water into space. D. The planet's atmosphere was gradually lost to space.
d
Why do astronomers think that neutron stars were formed in supernova explosions? Choose one: A. A pulsar spins very rapidly, as did the massive star just before it exploded. B. All supernova remnants contain pulsars. C. Pulsars are made of heavy elements, such as those produced in supernova explosions. D. Pulsars sometimes have material around them that looks like the ejecta from supernovae.
d
Why do the outer layers fall onto the core? Choose one: A. magnetic fields B. photon pressure C. nuclear forces D. gravity
d
Suppose Jupiter were not a planet, but instead were a G5 main-sequence star with a mass of 0.8 MSun. How could this affect the Sun as the G5 star came to the end of its life? Choose one or more: A. The G5 would be too far away to impact the Sun. B. The G5 star would die first, exploding as a nova, and thus causing the Sun to explode as well. C. Because the Sun would already be dead as a white dwarf and thus incapable of further change, it would not be impacted by the G5's death. D. The G5 may have transferred all its mass to the Sun, causing the Sun to explode as a Type I supernova. E. The Sun would have already become a white dwarf, and as the G5 swelled into a red giant, material from it would be transferred to an accretion disk around the Sun, making the Sun explode as a nova.
d e
