Download sc_examII_fall_2002 - University of Maryland

Fall 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. In the Cygnus X-1 system, the X-rays are explain by astronomers as
A. strong radiation emitted by a supergiant star.
B. a distant galaxy that has recently been born.
C. coming from very hot gas in a black hole’s accretion disk.
D. what’s left after a pulsar stopped pulsing.
E. matter and antimatter annihilation.
2. According to Einstein’s theory of general relativity, the gravitational force results from
A. pressure exerted by radiation.
B. interatomic forces between masses.
C. curvature of space by mass.
D. the expansion of the universe.
E. the relative weights of the objects involved.
3. The 65 million year old clay layer containing Iridium that is observed all over the Earth is
cited as support for
A. the formation of the Moon.
B. continental drift.
C. magnetic reversal.
D. a large asteroid impact.
E. the presence of an atmosphere rich in oxygen.
4. Magnetic fields inhibit the convective flow of energy to the Sun’s photosphere and disrupt the
granulation pattern. This process leads to the formation of
A. prominences.
B. sunspots.
C. meteorites.
D. hydrogen absorption lines.
E. hydrogen emission lines.
5. Life on Earth chemically depends on which atom that forms long chains with itself leading to
complex molecules?
A. oxygen
B. hydrogen
C. iron
D. nitrogen
E. carbon
6. Given positions of stars A and B in the spectroscopic binary shown below, which spectrum
showing the H Alpha and H Beta absorption lines would represent the binary star’s spectrum at
this time?
Diagram will be given in Discussion Session
7. Using the Bohr atomic model representation, which atom has just absorbed a photon?
Indicate A or B or C
=proton
=electron
Diagram will be given in discussion session
8. Interstellar dust lying between a star and an observer on Earth will cause the star to appear
A. dimmer and redder.
B. dimmer and bluer.
C. brighter and redder.
D. brighter and bluer.
E. unaffected due to the wavelength of visible light.
9. Titan, moon of Saturn, is of interest and will be visited by the Cassini probe that will arrive at
Saturn in 2004. What observation of Titan did the earlier Voyager mission make?
A. Voyager photographed active volcanoes on Titan's surface.
B. Voyager detected a ring around this satellite.
C. Voyager noticed a large amount of radio emission from Titan.
D. Voyager couldn't photograph Titan's surface due to its orange, hazy atmosphere.
E. Voyager's life detection experiments gave inconclusive results.
10. The reason that astronomers use the concept of absolute magnitude is to
A. make life difficult for ASTR 101 students.
B. allow stars to be compared with the effects of differing distances removed.
C. allow stars to be compared with the effects of differing masses removed.
D. allow stars to be compared with the effects of differing temperatures removed.
E. allow stars to be compared with the effects of differing radii removed.
11. The Leonid meteor shower occurred Nov. 18-19. The shower meteors seen were originally
part of
A. the asteroid belt.
B. the Sun.
C. one of the rings of Saturn.
D. a comet.
E. debris surrounding the Moon.
12. If a scale model of the Solar System were placed on Byrd Stadium football field here at the
University of Maryland, using the same scale, the closest star (other than the Sun) would be
A. a few hundred feet away.
B. a few miles away.
C. a few hundred miles away.
D. a few thousand miles away.
E. at the Moon’s distance.
13. A planetary nebula, like the Ring Nebula shown in class, is
A. evidence that planets exist around other stars.
B. gas that is about to collapse and form planets.
C. a giant molecular cloud that is about to form new stars.
D. a very dense cloud with many organic molecules.
E. gas ejected by a star, which is becoming a white dwarf.
14. If the Earth were struck by a sizeable asteroid (more than 10 km across), it is most likely that
A. our protective atmosphere would cause the asteroid to vaporize.
B. the impact would split the Earth into two.
C. an environmental crisis would trigger a mass extinction.
D. it would make a crater that would exist for billions of years.
E. the dinosaurs would return.
15. A gigantic solar flare occurred on the Sun this morning. Mrs. Deming was excited and told
her ASTR 101 class to expect (if it is clear)
A. a full moon tonight.
B. an eclipse.
C. a meteor shower.
D. an aurora.
E. dangerous cosmic rays.
16. Emission nebulae, like the North American Nebula, appear red due to emission by hydrogen
atoms
A. as electrons move from level 2 to level 3.
B. as electrons move from level 3 to level 2.
C. as the electrons break completely free from the nuclei.
D. due to the electrons and protons colliding.
E. as fusion begins in the cloud.
17. If you were thrown onto the surface of Mars without a spacesuit, what would be your most
likely cause of death?
A. You would be crushed to death by the high atmospheric pressure.
B. You would slowly freeze to death.
C. You would suffocate and have problems dealing with the low atmospheric pressure.
D. Volcanic activity would bury you.
E. Hungry martian microbes would eat you.
18. At the center of the Crab Nebula supernova remnant in Taurus lies a
A. white dwarf.
B. planet.
C. black hole.
D. pulsar.
E. protostar.
19. Jupiter's ring was first detected
A. by Galileo with his telescope.
B. when Voyager flew by Jupiter.
C. using a radio telescope.
D. using the Hubble Space telescope.
E. by amateur astronomers as they watched the comet hit Jupiter.
20. The peak or maximum wavelength that you are emitting right lies in which portion of the
electromagnetic spectrum?
A. X ray
B. ultraviolet
C. visible
D. infrared
E. radio
21. The protons and neutrons in a helium nucleus are held together by the
A. gravitational force.
B. electromagnetic force.
C. strong nuclear force.
D. chemical force.
E. all of the above.
22. The classroom demonstration in which a student was placed in the spinning chair with
weights was meant to show what happens
A. as a neutron star collapses and its rotation speeds up.
B. when gravity is balanced by rotation.
C. when a fast-spinning object ejects matter into space.
D. as weightlessness takes control.
E. to stars in a binary system when one explodes.
23. Radio waves have _______wavelength and _____photon energy when compared to visible
light.
A. the same; the same
B. shorter; greater
C. shorter; less
D. longer; greater
E. longer; less
24. A comet's perihelion distance is 1 AU from the Sun. Its aphelion distance is 20 AU. How
does the intensity of sunlight compare at these two distances?
A. It is 20 times less at aphelion.
B. It is 20 times greater at aphelion.
C. It is the same at both perihelion and aphelion.
D. It is 400 times less at perihelion.
E. It is 400 times greater at perihelion.
25. Mizar in Ursa Major, the Big Dipper, has been studied by astronomers using a spectrograph.
Spectral studies have revealed
A. that Mizar is a quadruple star system.
B. that Mizar is a triple star system.
C. that Mizar has a blue shift and is moving away from us.
D. that Mizar has a red shift and is approaching us.
E. that there is no hydrogen present in Mizar.
SHORT ANSWER QUESTIONS (50 pts.)
Using what you have learned in ASTR 101, answer the following questions completely.
26. a) Describe and account for the physical changes that we see from Earth as a comet
approaches the Sun. (3 pts.)
b) Asteroids have been photographed by spacecraft. Describe what one looks like. (2 pts.)
c) Earth and Venus were very much alike in their past. Both planets had considerable carbon
dioxide released into their atmospheres by volcanic activity. Where is the carbon dioxide today
on Venus? What happened differently on Earth? (4 pts.)
EXTRA CREDIT (2 pts. max) Would you classify Pluto as a planet or as a Kuiper Belt Object?
Explain your answer.
27. a) You used the heliocentric parallax method to find stellar distances using computers in Lab
#6. Describe this method and discuss any limitations. (3 pts.)
b) Explain how astronomers use what they know about the Doppler Effect to investigate the
radial motion of a star. (3 pts.)
c) Describe the surface of Jupiter’s inner large moon, Io. Why is Io’s surface different from that
on our Moon? (3 pts.)
28. The Sun is a main sequence star.
a) What does this (underlined phrase) mean in terms of what is happening inside the Sun?
Describe how solar energy is produced. (4 pts.)
b) In approximately 5 billion years the Sun will become a __________________________.(1 pt.)
How will this future Sun’s internal structure differ from its current arrangement? (3 pts.)
c) The final stage that the Sun will reach at the end of its life is______________________.(1 pt.)
Describe what the Sun will be like physically (size, mass, temperature, luminosity) at this time.
(2 pts.)
29 a) What determines whether or not a star explodes as a supernova? Explain the events that
lead up to the actual explosion. (4 pts.)
b) Describe what is left of the star after the supernova. (Mention both possibilities and what
determines what you get.) (3 pts.)
c) With the aid of a labeled sketch, explain how the observations of pulsars are produced.
(4 pts.)
30. Given the HR Diagram, answer the following questions (1 pt. each part unless noted):
Diagram will be given in Discussion Section.
a) The Sun’s coordinates on the HR Diagram are:
luminosity = ______ and spectral type = _______.
b) Indicate on the HR Diagram above where you would find a red giant star with the letter X.
c) The axis labeled spectral type could also be labeled ____________________________.
d) Indicate where you would find a 30 solar mass main sequence star with the letter Y.
Why would an astronomer state that this star must be relatively young? (4 pts.)
e) Why must a white dwarf star contain less than 1.4 solar masses? (2 pts.)
EXTRA CREDIT (2 pts. maximum) When would be the best time to observe an asteroid that is
at opposition? Explain your answer.