Chapter 10

What are the two primary methods by which planets have been found around other stars in our galaxy? I) Direct images in visible and infrared light II) Indirectly by detecting the motion of the host star III) Indirectly by measuring the drop in brightness of the host star when the planet crosses our line of sight...... -II and III -I and III -I and II

-II and III

What could happen in planetary systems where the nebular gas is quickly disbursed? -The only planets would be more massive than Jupiter. -No terrestrial planets would form. -Many planets would be destroyed by migration onto the central star. -Large ice-rich planetesimals would not be able to gather hydrogen and helium and become gas giants.

-Large ice-rich planetesimals would not be able to gather hydrogen and helium and become gas giants.

A transiting extrasolar planet is observed to block 1% of its host star's light. How does the size of this planet compare to the host star? -The planet's radius is 0.1% of the host star's radius. -The planet's radius is 1% of the host star's radius. -The planet is the same size as the host star. -The planet's radius is 10% of the host star's radius.

-The planet's radius is 10% of the host star's radius.

How does the theory of planetary migration in disks possibly account for the highly eccentric orbits discovered for some extrasolar planets? -When migrating planets collide, they would move onto more eccentric orbits. -When migrating planets pass close enough for a gravitational encounter, one may be flung from the system while the other is shifted to a highly elliptical orbit. -When a planet migrates onto the surface of the star, the additional stellar mass would disrupt the orbits of the remaining planets. -A migrating planet would create waves in the planet forming disk, which would in turn lead to the formation of planets on highly elliptical orbits.

-When migrating planets pass close enough for a gravitational encounter, one may be flung from the system while the other is shifted to a highly elliptical orbit.

Which of the following methods has led to the most confirmed discoveries of massive planets orbiting near their parent stars? -detecting the starlight reflected off the planet -detecting the shift of the star's position against the sky due to the planet's gravitational pull -detecting the gravitational effect of an orbiting planet by looking for the Doppler shifts in the star's spectrum -detecting a planet ejected from a binary star system -detecting the infrared light emitted by the planet

-detecting the gravitational effect of an orbiting planet by looking for the Doppler shifts in the star's spectrum

Which two quantities need to be measured in order to determine the density of an extrasolar planet? -radius and orbital period -mass and radius -mass and composition -orbital period and mass -radius and composition

-mass and radius

The astrometric method of planet detection works best for -massive planets around nearby stars. -planets in edge-on orbits. -large planets around distant stars. -massive planets around distant stars. -large planets around nearby stars.

-massive planets around nearby stars.

What is the most accurate way to measure the surface temperature of an extrasolar planet? -measure the drop in total infrared light when the planet passes behind the star -identify the composition of the planet's atmosphere through spectroscopy -identify the planet's peak wavelength of emission -calculate the size of the planet by the amount of light it blocks during transit -estimate the temperature based on the planet's mass

-measure the drop in total infrared light when the planet passes behind the star

The Doppler method can be used to measure the eccentricity of a planet's orbit by -measuring the asymmetries in the velocity curve. -measuring the speed at which the star orbits the mutual center-of-mass of the star and planet, and using Newton's theory of gravity. -measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law. -measuring the amount by which the starlight is reduced when the planet transits.

-measuring the asymmetries in the velocity curve.

The depth of the dip in a star's brightness due to the transit of a planet depends most directly on -the size of the planet's orbit. -the planet's density. -the planet's size. -the eccentricity of the planet's orbit. -the planet's mass.

-the planet's size.

The reason that most extrasolar planets discovered by the Doppler method are found close to their parent stars is -the closer to a star, the hotter and therefore brighter the planet is. -planets that are close to a star are heated up and therefore larger. -the wavelength shift of the star's spectrum is larger. -they transit more frequently, and have thus been more likely to be detected in the short time we have been searching for them. -more of the starlight is blocked by the planet when it transits the star.

-the wavelength shift of the star's spectrum is larger.

The reason that most extrasolar planets discovered by the transit method are found close to their parent stars is -they transit more frequently and are more likely to be detected in the short time we have been searching for them. -the closer to a star, the hotter and therefore brighter the planet is. -planets that are close to a star are heated up and therefore larger. -more of the starlight is blocked by the planet when it transits the star. -the wavelength shift of the star's spectrum is larger.

-they transit more frequently and are more likely to be detected in the short time we have been searching for them.

Statistical evidence suggests that about ________ percent of all stars have an approximately Earth-sized planet orbiting in a region around the star where water could exist as a liquid on the planet's surface. -10 -20 -30 -40

20

The Doppler method can be used to estimate the semimajor axis of a planet's orbit by -measuring the asymmetries in the velocity curve. -measuring the speed at which the star orbits the mutual center-of-mass of the star and planet, and using Newton's theory of gravity. -measuring the amount by which the starlight is reduced when the planet transits. -measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law.

measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law.