Chapter 10

What is the GAIA mission? A NASA's mission which searched for planetary transits. An orbital telescope which searches for a star's orbital movement around the center of mass by looking for changing Doppler shifts in its spectrum. A European Space Agency's mission which has the goal of performing astrometric observations. None of the above.

A European Space Agency's mission which has the goal of performing astrometric observations.

What was the Kepler mission? A European Space Agency's mission which performed astrometric observations. A NASA's mission which searched for planetary transits. An orbital telescope which searched for a star's orbital movement around the center of mass by looking for changing Doppler shifts in its spectrum. None of the above.

A NASA's mission which searched for planetary transits.

As you've seen, the nebular theory predicts that a cloud that gives birth to planets should have the shape of a spinning disk. Which observable property of our solar system supports this prediction? The four largest planets all have disk-shaped ring systems around them. There are two basic types of planets in our solar system: terrestrial and jovian. The orbit of Earth's Moon lies very close to the ecliptic plane. All the planets orbit the Sun in the same direction and in nearly the same plane.

All the planets orbit the Sun in the same direction and in nearly the same plane.

Why didn't one form in our solar system? Because our jovian planets are very far away beyond the frost line. Because our jovian planets are very large. Because the nebula must have dispersed before the formation of our jovian planets. Because the nebula must have dispersed shortly after the formation of our jovian planets.

Because the nebula must have dispersed shortly after the formation of our jovian planets.

The nebular theory also predicts that the cloud will flatten into a disk as it shrinks in size. Which of the following best explains why the collapsing cloud should form a disk? All collapsing objects tend to flatten into a disk, regardless of their rotation. Colliding cloud particles exchange angular momentum and, on average, end up with the rotation pattern for the cloud as a whole. As a star forms near the cloud center, its wind blows away material that is not aligned with its equator, thereby leaving an equatorial disk of material. Gravity pulls more strongly on material along the rotation axis than perpendicular to it, bringing this material downward into a disk.

Colliding cloud particles exchange angular momentum and, on average, end up with the rotation pattern for the cloud as a whole.

Today, the leading hypothesis for the existence of hot Jupiters is that they formed in their outer solar systems and then migrated inward. Why did this hypothesis gain favor over alternative ideas? The migration hypothesis requires the least modification to the nebular theory and therefore was preferred over any alternatives. Telescopic observations have revealed several star systems in which planets can be seen migrating rapidly inward. Scientists did not find any reason to favor any of the alternate explanations, so by process of elimination they settled on the migration hypothesis. Computer models that simulate planetary formation show that interactions between young planets and other material in the surrounding disk can cause planetary migration.

Computer models that simulate planetary formation show that interactions between young planets and other material in the surrounding disk can cause planetary migration.

How do we think hot Jupiters formed? Hot Jupiters formed beyond the frost line and stayed there. Hot Jupiters formed beyond the frost line, as in our solar system, and migrated inward due to interaction with the solar nebula. Hot Jupiters formed inside the frost line and stayed there. Hot Jupiters formed inside the frost line, as in our solar system, and migrated beyond due to interaction with the solar nebula.

Hot Jupiters formed beyond the frost line, as in our solar system, and migrated inward due to interaction with the solar nebula.

The solar system has two types of planets, terrestrial and jovian. According to the nebular theory, why did terrestrial planets form in the inner solar system and jovian planets in the outer solar system? After the planets formed, the Sun's gravity pulled the dense terrestrial planets inward, leaving only jovian planets in the outer solar system. All the planets started out large, but the Sun's heat evaporated so much material that the inner planets ended up much smaller. Denser particles of rock and metal sank into the inner solar system, leaving only gases in the outer solar system. Ices condensed only in the outer solar system, where some icy planetesimals grew large enough to attract gas from the nebula, while only metal and rock condensed in the inner solar system, making terrestrial planets.

Ices condensed only in the outer solar system, where some icy planetesimals grew large enough to attract gas from the nebula, while only metal and rock condensed in the inner solar system, making terrestrial planets.

How does the transit method tell us planetary size, and in what cases can we also learn mass and density? In the transit method, the fraction of light absorbed is the ratio of the planet's area to the star's area, so we can find the density of the planet. If we also measure its physical size via radial velocity, we can calculate its mass. In the transit method, the fraction of light absorbed is the ratio of the planet's area to the star's area, so we can find the mass of the planet. If we also measure its physical size via radial velocity, we can calculate its density. In the transit method, the fraction of light absorbed is the ratio of the planet's area to the star's area, so we can find the density of the planet. If we also measure its mass via radial velocity, we can calculate its physical size. In the transit method, the fraction of light absorbed is the ratio of the planet's area to the star's area, so we can find the physical size of the planet. If we also measure its mass via radial velocity, we can calculate its density.

In the transit method, the fraction of light absorbed is the ratio of the planet's area to the star's area, so we can find the physical size of the planet. If we also measure its mass via radial velocity, we can calculate its density.

How do the orbits of known extrasolar planets differ from those of planets in our solar system? Many of orbits of extrasolar planets were much more eccentric and much nearer their stars than the jovian planets of our solar system. Many of orbits of extrasolar planets were much more eccentric and much farther their stars than the jovian planets of our solar system. Many of orbits of extrasolar planets were much less eccentric and much farther their stars than the jovian planets of our solar system. Many of orbits of extrasolar planets were much less eccentric and much nearer their stars than the jovian planets of our solar system.

Many of orbits of extrasolar planets were much more eccentric and much nearer their stars than the jovian planets of our solar system.

A star is seen to have two transiting planets. Planet 1 transits every 3 months, and Planet 2 transits every 15 months. What can we infer about their orbits? (Hint: Review the use of Newton's version of Kepler's Third law from chapter 4 in the textbook) Planet 2's semimajor axis is about 5 times larger than Planet 1's. Planet 2's semimajor axis is about 3 times larger than Planet 1's. Planet 2's semimajor axis is about 3 times smaller than Planet 1's. Planet 2's semimajor axis is about 5 times smaller than Planet 1's.

Planet 2's semimajor axis is about 3 times larger than Planet 1's.

Summarize the evidence that the planet orbiting 51 Pegasi is a hot Jupiter. Check all that apply. The Doppler data show that 51 Pegasi has about half the mass of Jupiter. 51 Pegasi lies so close to the star that its "year" lasts only 4 Earth days, which means its surface temperature is probably over 1000 K. The Doppler data show that 51 Pegasi has about two the mass of Jupiter. 51 Pegasi lies so far to the star that its "year" lasts 700 Earth days, which means its surface temperature is probably over 1000 K.

The Doppler data show that 51 Pegasi has about half the mass of Jupiter.; 51 Pegasi lies so close to the star that its "year" lasts only 4 Earth days, which means its surface temperature is probably over 1000 K.

Briefly describe the Doppler method. The Doppler technique watches for movement in stars by looking for periodic Doppler shifts. It's best for detecting massive planets with close-in orbits. It detects planets in all orbit orientations except face-on. The Doppler technique watches for tiny movements of a star against the background of other stars. It's best for detecting massive planets with close-in orbits. It detects planets in all orbit orientations except face-on. The Doppler technique watches for tiny movements of a star against the background of other stars. It's best for detecting massive planets that orbit far from their stars, even though distant planets take longer to orbit. Current technology limits its use to very rare cases. It works best for nearby stars. The Doppler technique watches for the changes brightness of a star as the planet passes in front of the star's disk. The star's light dims slightly because the planet is dimmer than the star. This technique works only in the rare cases when the planet's orbit is nearly edge-on as seen from Earth, since otherwise the planet will pass to one side of the star as it orbits.

The Doppler technique watches for movement in stars by looking for periodic Doppler shifts. It's best for detecting massive planets with close-in orbits. It detects planets in all orbit orientations except face-on.

Briefly describe the astrometric method. The astrometric technique watches for the changes brightness of a star as the planet passes in front of the star's disk. The star's light dims slightly because the planet is dimmer than the star. This technique works only in the rare cases when the planet's orbit is nearly edge-on as seen from Earth, since otherwise the planet will pass to one side of the star as it orbits. The astrometric technique watches for tiny movements of a star against the background of other stars. It's best for detecting massive planets that orbit far from their stars, even though distant planets take longer to orbit. Current technology limits its use to very rare cases. It works best for nearby stars. The astrometric technique watches for movement in stars by looking for periodic Doppler shifts. It's best for detecting massive planets with close-in orbits. It detects planets in all orbit orientations except face-on. The astrometric technique watches for movement in stars by looking for periodic Doppler shifts. It's best for detecting massive planets that orbit far from their stars, even though distant planets take longer to orbit. Current technology limits its use to very rare cases. It works best for nearby stars.

The astrometric technique watches for tiny movements of a star against the background of other stars. It's best for detecting massive planets that orbit far from their stars, even though distant planets take longer to orbit. Current technology limits its use to very rare cases. It works best for nearby stars.

How can gravitational tugs from orbiting planets affect the motion of a star? The planet and the star both make orbits about a common center of mass. The star, being much larger than the planet, has a much smaller orbit. But it does move slightly. Gravitational tugs from orbiting planets don't affect the motion of a star. The star orbits the center of planet. The star, being much larger than the planet, has a much greater orbit. The planet and the star both make orbits about a common center of mass. The star, being much larger than the planet, has a much larger orbit.

The planet and the star both make orbits about a common center of mass. The star, being much larger than the planet, has a much smaller orbit. But it does move slightly.

Two stars with about the same mass are found to have transiting planets with similar semi-major axes. Star 1 exhibits a Doppler shift twice as large as Star 2. What can we determine about these two systems? The planet around Star 1 is more massive than the planet around Star 2. The planet around Star 1 has a thicker atmosphere than the planet around Star 2. The planet around Star 2 is more massive than the planet around Star 1. The planet around Star 2 has a thicker atmosphere than the planet around Star 1.

The planet around Star 1 is more massive than the planet around Star 2.

You observe a star very similar to our own Sun in size and mass. This star moves very slightly back and forth in the sky once every 4 months, and you attribute this motion to the effect of an orbiting planet. What can you conclude about the orbiting planet? The planet must have a mass about the same as the mass of Jupiter. The planet must be farther from the star than Neptune is from the Sun. The planet must be closer to the star than Earth is to the Sun. You do not have enough information to say anything at all about the planet.

The planet must be closer to the star than Earth is to the Sun.

Some extrasolar planets are likely to be made mostly of gold. The statement doesn't make sense. We know of no process that enriches gold over other metals. The statement doesn't make sense. Gold can be formed only on Earth. The statement makes sense. Some of the processes that occur during the formation of a solar system can separate gold from other metals in quantities sufficient to form a planet. The statement doesn't make sense. Gold is unstable and decays into lighter nuclei.

The statement doesn't make sense. We know of no process that enriches gold over other metals.

Current evidence suggests that there could be 100 billion or more planets in the Milky Way Galaxy. The statement doesn't make sense. Results from Doppler and transit studies indicate that planets are much less common than stars in our galaxy. The statement doesn't make sense. The Way Galaxy is too small to comprise of 100 billion planets. The statement makes sense. In fact, 100 billion planets are already confirmed in our galaxy. The statement makes sense. In fact, results from Doppler and transit studies already hint that planets are at least as common as stars in our galaxy.

The statement makes sense. In fact, results from Doppler and transit studies already hint that planets are at least as common as stars in our galaxy.

Some extrasolar planets are likely to be made mostly of water. The statement doesn't make sense. Water is formed only in artificial conditions. The statement doesn't make sense. Water can be formed only in our solar system. The statement makes sense. Water worlds have already been discovered. The statement doesn't make sense. Water can be formed only on Earth.

The statement makes sense. Water worlds have already been discovered.

The discovery of hot Jupiters led scientists to reconsider the nebuar theory. Which of the following best explains why the nebular theory(as it stood before the discoveries of extrasolar planets) had not predicted the existence of hot Jupiters? Scientists had no evidence that other stars could have disks of gas in which planets could form around. The nebular theory was designed to apply only to our solar system, so there was no reason to think it would apply to others. The nebular theory was fundamentally flawed and was incorrect about how planets form. There are no hot Jupiters in our solar system.

There are no hot Jupiters in our solar system.

Explain how alien astronomers could deduce the existence of planets in our solar system by observing the Sun's motion. Check all that apply. They could measure the small changes in position of the Sun to deduce the presence of our planets. They could measure the Sun's rotational velocity about its own axis to deduce the presence of our planets. They could measure the small velocity changes of the Sun to deduce the presence of our planets. It is impossible to deduce the presence of planets in our solar system

They could measure the small changes in position of the Sun to deduce the presence of our planets.; They could measure the small velocity changes of the Sun to deduce the presence of our planets.

What was so surprising about the first extrasolar planets that they forced a change in our theory of planet formation? They were massive like Jupiter, but very close to their host star. The extrasolar planet compositions were nothing like the planets in our own solar system. Rocky planets do not exist outside of our solar system. They were far less common than we suspected.

They were massive like Jupiter, but very close to their host star.

Why are these orbits surprising? This was surprising since our planet formation model suggests that planets should have nearly circular orbits and that jovian planets, which require ice to form, should form only farther out in the solar system. This was surprising since our planet formation model suggests that planets should have nearly circular orbits and that jovian planets, which require ice to form, should form nearer to the star in the solar system. This was surprising since our planet formation model suggests that planets should have eccentric orbits and that jovian planets, which require ice to form, should form only farther out in the solar system. This was surprising since our planet formation model suggests that planets should have eccentric orbits and that jovian planets, which require ice to form, should form only nearer out in the solar system.

This was surprising since our planet formation model suggests that planets should have nearly circular orbits and that jovian planets, which require ice to form, should form only farther out in the solar system.

How does the transit method work? To use the transit method, we monitor the movement in stars by looking for periodic Doppler shifts. It's best for detecting massive planets that orbit far from their stars, even though distant planets take longer to orbit. Current technology limits its use to very rare cases. It works best for nearby stars. To use the transit method, we monitor the tiny movements of a star against the background of other stars. It's best for detecting massive planets that orbit far from their stars, even though distant planets take longer to orbit. Current technology limits its use to very rare cases. It works best for nearby stars. To use the transit method, we monitor the movement in stars by looking for periodic Doppler shifts. It's best for detecting massive planets with close-in orbits. It detects planets in all orbit orientations except face-on. To use the transit method, we monitor the brightness of a star as the planet passes in front of the star's disk. The star's light dims slightly because the planet is dimmer than the star. This technique works only in the rare cases when the planet's orbit is nearly edge-on as seen from Earth, since otherwise the planet will pass to one side of the star as it orbits.

To use the transit method, we monitor the brightness of a star as the planet passes in front of the star's disk. The star's light dims slightly because the planet is dimmer than the star. This technique works only in the rare cases when the planet's orbit is nearly edge-on as seen from Earth, since otherwise the planet will pass to one side of the star as it orbits.

What is an "extrasolar planet"? a planet that is extra large compared to what we'd expect a planet that is considered an "extra," in that it was not needed for the formation of its solar system a planet that is larger than the Sun a planet that orbits a star that is not our own Sun

a planet that orbits a star that is not our own Sun

The first planets around other Sun-like stars were discovered by Huygens, following his realization that other stars are Suns. by Galileo following the invention of the telescope. at the turn of last century. about two decades ago. at the turn of this century.

about two decades ago

Which method could detect a planet in an orbit that is face-on to the Earth? transit method Doppler method astrometric method

astrometric method

How can astronomers measure the composition of an extrasolar planet's atmosphere? by comparing spectra for when the planet is in transit or eclipse with spectra taken at other times by measuring the Doppler shift of the host star by measuring the composition of the host star; the planet must have formed from the same initial material by measuring how brightly the planet glows in infrared light

by comparing spectra for when the planet is in transit or eclipse with spectra taken at other times

For a planet of a particular mass, the astrometric method will detect the largest stellar motion if the planet orbits very close to its star around an extremely distant star farther from its star

farther from its star

Which one of the following can the transit method tell us about a planet? the eccentricity of its orbit its size its mass

its size

Our modern theory of solar system formation—the nebular theory—successfully accounts for all the major features of our own solar system. However, when the first hot Jupiters were discovered, their existence seemed inconsistent with the nebular theory because this theory predicts that __________. any system with jovian planets should also have terrestrial planets planetary systems should be extremely rare jovian planets can form only in the cold, outer regions of a solar system jovian planets located close to their stars should have evaporated by now

jovian planets can form only in the cold, outer regions of a solar system

Assume a solar-mass star and a "wobble" period of one year. The larger the velocity change in the wobble, the larger the _______. size of the planet's orbit. mass of the planet. distance to the planet. distance to the star.

mass of the planet

What new process was added to our theory of planet formation to explain these surprising extrasolar planets? condensation evaporation migration disk formation

migration

Based on what we know about our own solar system, the discovery of hot Jupiters came as a surprise to scientists because these planets are __________. so close to their stars so large so small made of different materials than either the terrestrial or jovian planets in our solar system

so close to their stars

Complete this statement. The larger the decrease in the star's brightness as the planet transits in front of a star, _______. the larger the distance to the star. the larger the size of the planet. the larger the size of the planet's orbit. the larger the size of the star.

the larger the size of the planet

Observations show that interstellar clouds can have almost any shape and, if they are rotating at all, their rotation is not perceptible. However, the nebular theory predicts that a cloud will rotate rapidly once it shrinks to a relatively small size. What physical law explains why a collapsed cloud will rotate rapidly? Kepler's second law the universal law of gravitation the law of conservation of angular momentum the law of conservation of energy Newton's third law of motion

the law of conservation of angular momentum

The nebular theory also predicts that the cloud should heat up as it collapses. What physical law explains why it heats up? the universal law of gravitation Newton's third law of motion Kepler's second law the law of conservation of angular momentum the law of conservation of energy

the law of conservation of energy

Which detection method was used by the Kepler mission? transit method astrometric method Doppler method

transit method