Spring 2002 Exam II
MULTIPLE CHOICE QUESTIONS (50 pts.)
Choose the BEST answer to each of the following questions using what you have learned in ASTR 101. Indicate your choice on the scantron. (2 pts. each)
1. For the diagram below which spectrum would you observe?
Diagram will be given in Discussion Section
A. continuous
B. absorption
C. emission
D. blue shifted
E. red shifted
2. The smaller the parallax angle for a star,
A. the less massive the star.
B. the more massive the star.
C. the smaller the distance to the star.
D. the greater the distance to the star.
E. both A and C
3. By combining information from both the light curve and spectrum of Algol, the demon star, astronomers have been able to determine
A. the age of Algol.
B. that Algol has a black hole companion.
C. the amount of interstellar dust between Algol and Earth.
D. that Algol is about to blow up.
E. the diameters of the stars in this eclipsing binary.
4. Ozone in the Earth’s stratosphere
A. is the most abundant atmospheric greenhouse gas.
B. breaks down infrared radiation.
C. absorbs much of the incoming ultraviolet solar radiation.
D. forms when ordinary oxygen mixes with freon.
E. has been building up as a result of industrial combustion.
5. The speed of light through a vacuum is
A. greatest for red light due to its longer wavelength.
B. greatest for blue light due to its higher photon energy.
C. greatest for only the shortest wavelength photons.
D. the same for all types of electromagnetic radiation.
E. dependent on the frequency of the electromagnetic radiation.
6. The mass of Jupiter was first calculated
A. from analysis of the motions of its moons.
B. using its distance from the Sun and its rotational period.
C. using its angular size and distance from Earth.
D. using data from spacecraft flybys.
E. by measuring the time that it takes for the Red Spot to disappear from view.
7. The gas tail of a comet develops when
A. part of the nucleus drifts in the direction opposite to the comet’s motion.
B. the solar wind pushes away gases that has sublimated from the nucleus.
C. gravitational forces pull loosely held material toward the Sun.
D. gravitational forces pull loosely held material out of the Sun toward the comet.
E. the comet nears aphelion.
8. The granules seen in the solar photosphere are believed to be energy brought up from below by
A. radiation.
B. convection.
C. conduction.
D. rotation.
E. volcanic activity.
9. If you observe five objects that have different temperatures, the hottest object would be the one emitting primarily
A. radio photons.
B. red photons.
C. blue photons.
D. ultraviolet photons.
E. X-ray photons.
10. Saturn is 10 times farther from the Sun than Earth. Comparing the intensity of sunlight at Saturn’s distance to the intensity on Earth, what can be said?
A. It is the same.
B. It is 10 times greater at Saturn.
C. It is 10 times less at Saturn.
D. It is 100 times greater at Saturn.
E. It is 100 times less at Saturn.
11. The naked-eye planets have been in the news lately because
A. several new naked-eye planets have been detected.
B. a collision is predicted.
C. They are all visible in the western sky after sunset.
D. They will all lie behind the Moon on May 5.
E. They will all lie behind the Sun on May 5.
12. If a scale model of the Solar System were constructed on the Byrd Stadium football field here at the University of Maryland, where would the closest star (other than the Sun) be located?
A. at Baltimore harbor
B. in Los Angeles
C. in Boston
D. somewhere in China
E. near the Moon
13. An astronomer who wanted to observe a protostar would have the greatest chance for success using ______telescope.
A. an infrared
B. an X-ray
C. an optical (visible light)
D. an ultraviolet
E. a gamma ray
14. The emission and absorption spectra of an element differ in which obvious way?
A. The emission spectrum contains more lines.
B. The absorption spectrum contains more lines.
C. The emission spectrum is shifted to the left (toward the blue side) of the absorption
spectrum.
D. The emission spectrum is shifted to the right (toward the red side) of the absorption
spectrum.
E. The lines are in the same wavelength positions, but are bright for emission and dark
for absorption.
15. Using the Bohr atomic model representation, which atom has just emitted a photon?
Indicate A or B or C =proton=electron
Diagram will be given in Discussion Section
16. Given H Alpha and H Beta absorption lines in this spectrum for a binary star, which drawing represents the positions of stars A and B at the time the spectrum was taken?
Diagram will be given in discussion section
17. Cygnus X-1 is a good black hole candidate. Astronomers know a lot about this object because it is also
A. a neutron star.
B. a pulsar.
C. in a binary system.
D. in a star cluster.
E. in our Solar System.
18. If all of the polar cap material on Mars could be made to sublimate simultaneously, the Martian atmosphere would
A. become thicker and the temperature would increase.
B. become thicker and the temperature would decrease.
C. become thinner and the temperature would increase.
D. become thinner and the temperature would decrease.
E. escape immediately.
19. The core of an aging massive supergiant is
A. layered with lighter elements in the center.
B. layered with heavier elements in the center.
C. uniformly composed of hydrogen and helium.
D. uniformly composed of helium.
E. composed of molecules containing mostly carbon and iron.
20. A star at the center of a planetary nebula
A. has just been born.
B. is fusing hydrogen into helium in its core.
C. will shortly become a supernova.
D. is collapsing and will eventually stabilize as a white dwarf.
E. will stabilize when hydrogen fusion produces enough energy.
21. Halley’s comet is named after Sir Edmund Halley because
A. he was the first person to see it.
B. he correctly calculated its orbital period.
C. although he had nothing to do with the comet, he was famous at the time.
D. Galileo discovered it and named it after his friend.
E. he was the British Royal Astronomer when the comet appeared.
22. In Lab #8, Stellar Spectra, you used the distance modulus (spectroscopic parallax method) to find the distance to “Bell’s cluster.” Why won’t the heliocentric parallax method (d=1/p) that you used in computer Lab #6 work? Because Bell’s cluster
A. has a tilt so that parallax can’t be observed.
B. is at a distance of more than 200 parsecs, too far to show a reliable parallax shift.
C. moves so rapidly that no reliable measurement can be made.
D. has no stars with a red shift.
E. has no stars that are variables.
23. Between the orbits of which planets do most of the asteroids in the Solar System reside?
A. Earth and Mars
B. Mercury and Venus
C. Mars and Jupiter
D. Neptune and Pluto
E. Jupiter and Saturn
24. A star in Sagittarius has an A-type spectrum (surface temperature = 10,000 Kelvins) but its wavelength of maximum intensity (peak wavelength) is at 6500 Angstroms (red in color). What is the most likely explanation?
A. The star is greatly red shifted.
B. This star is very old.
C. The star’s light has been affected by the Earth’s atmosphere.
D. The star’s light has passed through interstellar dust.
E. The star is a red giant.
25. The total amount of time that the Sun will exist as a main sequence star is estimated to be
A. 10 million years.
B. 100 million years.
C. 10 billion years.
D. 100 billion years.
E. 1 trillion years.
SHORT ANSWER QUESTIONS (50 pts.)
Using what you have learned in ASTR 101, answer the following questions.
.
26. a) Two potential problems threaten to deterraform the Earth. Describe these potential problems and how humans may be contributing to them. (4 pts.)
b) It is theorized that Earth was struck by a sizeable asteroid or comet nucleus (at least 6 miles across) 65 million years ago. Describe events that scientists believe led to a mass extinction at that time. (3 pts.)
c) What observations support this theory? Explain. (3 pts.)
27. a) You read in a magazine that an astronomer has determined that the bright star Sirius is approaching the Earth at a velocity of 8 km/sec. How was this information determined? Describe the method. (3 pts.)
b) You hear a radio report that it might be possible to observe an aurora in College Park if clear tonight. What occurred that prompted this report? Describe how an aurora is produced. (4 pts.)
c) On the evening of May 5, the Eta Aquarid meteor shower will occur. Explain why a meteor shower like the Eta Aquarids occurs at the same time each year. (3 pts.)
28. a) Describe what is occurring now in the Sun to produce its energy and maintain its stability. (4 pts.)
b) When the Sun ends its main sequence lifetime, what is the next phase of stellar evolution that it will enter? Describe what will happen inside the Sun and how the Sun will change. (4 pts.)
c) What is the final stage of stellar evolution for the Sun? How will it achieve stability at the very end of its life? (2 pts.)
29. a) Jupiter’s inner two large moons, Io and Europa, have interesting surfaces. Describe them. (4 pts.)
b) If clear, the Sun will be visible for 4 minutes after it physically dips below the horizon today. Explain why. (3 pts.)
c) How do astronomers explain a pulsar’s radio wave variations? Include a labeled sketch.
(4 pts.)
30. Given the HR Diagram, answer the following questions:
Diagram will be given in Discussion Section
a) Indicate the Sun’s position with a X. (1 pt.)
b) Indicate where you would find a white dwarf with S. (1 pt.)
c) On the main sequence, label where you would find a high mass star (~20 solar masses) withD and a low mass star (~0.5 solar masses) with E. (2 pts.)
d) Star D will become a supernova shortly after its core contains mostly ______. (1 pt.)
If the remnant core is greater than ___ solar masses it will become ______(2 pts.)
e) Stars T and R are both K3 stars. These stars have the same ______(1 pt.)
f) Why is star T 100 times more luminous than star R? (1 pts.)
EXTRA CREDIT (2 pts. maximum each question)
Why do sunspots appear dark? Explain.
Describe the message carried aboard the Voyager spacecraft.