ASTR 1020 Chp. 6, 7, 13, 14 Multiple Choice

A certain star in the sky shows a parallax angle of .5 arc seconds. Due to the Earth's motion around the Sun, its distance from us is: A .5 parsecs B 1 parsec C 2 parsecs D 5 parsecs

C

Which property of an extrasolar planet cannot be determined using the Doppler effect? A orbital period B orbital distance C orbital speed D mass E radius

E

In practice, the smallest angular size that you can resolve with a 10-inch telescope is governed by the: A. blurring caused by Earth's atmosphere; B diffraction limit of the telescope; C size of the primary mirror; D magnification of the telescope.

A

Suppose that astronomers found a rocky, terrestrial planet beyond the orbit of Neptune. What is the most likely explanation for its origin? A It formed close to the Sun and migrated outward. B It formed in that location and was not disturbed by migration C It formed later in the Sun's history than other planets D It is a captured planet that formed around another star

A

Where does most of the angular momentum of the original cloud go? A into the orbital angular momentum of planets B into the star C into the spin of planets D lost along the jets from the star

A

Why are all large astronomical telescopes reflectors (choose all reasons that apply)? A. chromatic aberration is minimized; B. they are not as heavy; C. they can be shorter; D. the glass doesn't need to be curved.

A, B, C

High-performance computers have become one of an astronomer's most important tools. Which of the following require the use of that type of computer? (Choose all that apply.) A analyzing images taken with very large CCDs; B generating and testing theoretical models; C pointing a telescope from object to object D studying how astronomical objects or systems evolve

A, B, D

Which of the following pieces of evidence supports the nebular hypothesis? (choose all that apply) A Planets orbit the Sun in the same direction B The Solar System is relatively flat C The Earth has a large moon D We observe disks and gas around other stars

A, B, D

An alien on a nearby star watches the Earth transit the Sun. It observes the visible light brightness of the Sun drop by what fraction? (the Sun's radius is approximately 100 times the Earth's radius) A .01 B .0001 C .000001 D .00000001

B

In our Solar System, the inner planets are rocky because: A the original cloud had more rocky material near the center B warm temperatures in the inner disk caused inner planetesimals to be formed only of rocky material C the inner disk filled a smaller volume, so it was denser D the hydrogen and helium atoms were too low mass to remain in the inner disk

B

Stars A and B appear equally bright, but star A is twice as far away from us as star B. Which of the following is true? A Star A is twice as luminous as star B. B Star A is 4 times as luminous as star B. C Star B is twice as luminous as star A. D Star B is 4 times as luminous as star A. E Star A and star B have the same luminosity because they have the same brightness.

B

The surface of the Sun appears sharp in visible light because: A the photosphere is cooler than the layers below it; B the photosphere is thinner than the other layers in the Sun; C the photosphere is less dense than the convection zone; D the Sun has a distinct surface.

B

Two stars, A and B, are measured to have the same color and distance. Star B is observed to be 9 times brighter than A. What can you say about star B relative to A? A Star B has a larger mass than A B Star B has a larger radius than A C Star B has more iron than A D Star B has a higher temperature than A

B

When hydrogen is fused into helium, energy is released from: A gravitational collapse; B conversion of mass to energy; C the increase in pressure; D the decrease in the gravitational field.

B

Which method can be used to determine the radius of an extrasolar planet? A Doppler shift B transit method C microlensing D direct imaging E none of the above

B

Which type of binary star is identified by seeing periodic changes in the amount of light from a star/ A Doppler binary B eclipsing binary C spectroscopic binary D visual binary

B

Why does a disk heat up as it collapses? A conservation of angular momentum B conservation of energy C nebular hypothesis D the effect is simply a measurement error and it does not heat up

B

Choose the two qualities that describe a star located in the lower right of the H-R diagram A hot; B cool; C high luminosity; D low luminosity.

B, D

CCD cameras have much higher quantum efficiency than that of other detectors. Therefore, CCD cameras: A can collect photons for longer times; B can collect photons of different energies; C can generate a signal from fewer photons; D can split light into different colors.

C

How do neutrinos help us understand what is going on in the core of the Sun? A Neutrinos from distant objects pass through the Sun, probing the interior. B Neutrinos from the Sun pass easily through Earth. C Neutrinos created in fusion reactions at the core of the Sun easily escape.

C

Hydrostatic equilibrium in the Sun means that: A the Sun does not change; B the Sun absorbs and emits equal amounts of energy; C the outward force from radiation pressure balances the weight of overlying layers; D energy produced in the core per unit time equals energy emitted at the surface per unit time.

C

In miles or km the Sun-Earth distance is closest to: A 100 B 100,000 C 100,000,000 D 100,000,000,000

C

Spacecraft are the most effective way to study planets in our Solar System because: A planets move too fast across the sky for us to image them well from Earth B planets cannot be imaged from Earth C spacecraft can collect more information than is available just from images of Earth D space missions are easier than long observing campaigns

C

Suppose you observe a planet with an atmosphere composed mostly of hydrogen and helium. This planet is probably: A close to the central star B a very hot planet C a massive planet D a rocky planet

C

What is the most common method for discovering an Earth-mass planet around a star? A Doppler spectroscopy; B direct imaging; C transit; D astrometric

C

Which of the following properties is not useful in determining the masses of stars in a typical binary system? A the period of the orbits of the two stars B the average separation between the two stars C the radii of the two stars D the velocities of the two stars

C

If star A has twice the surface temperature of the Sun but has the same luminosity, the radius of Star A must be _______ the radius of the Sun. A 16 times B 4 times C 1/2 D 1/4

D

Sunspots appear dark because: A they have very low density; B magnetic fields absorb most of the light that falls on them; C they are regions of very high pressure; D they are cooler than their surroundings.

D

Which of the following is the biggest disadvantage of putting a telescope in space? A Astronomers don't have as much control in choosing what to observe. B Astronomers have to wait until the telescopes come back to Earth to get their images. C Space telescopes can observe only in certain parts of the electromagnetic spectrum. D Space telescopes are much more expensive and riskier than similar ground-based telescopes.

D

Which planet lost its primary atmosphere and now has a substantial secondary atmosphere? A Jupiter B Mercury C Saturn D Venus

D