Download Sample multiple choice questions for Exam 2

ASTRO 150
Astro 150 Exam 2 Sample
EXAM 2 - Sample
This examination is closed book. Please keep your answer sheet covered during the exam. Use a
soft pencil when completing the computer answer sheet.
* Sit in the seat with the number that matches the number on the computer answer sheet
* Write your NAME, SS#, and SECTION NUMBER on the COLORED PAGES of the exam.
* In the NAME portion of the computer sheet, fill in your last name, leave one blank space,
then continue with your first name.
* Enter your student ID number in the IDENTIFICATION NUMBER boxes of the computer
sheet.
* Write your Section Number in spaces K and L of the SPECIAL CODE
Wednesday
9:00AM
10:00AM
11:00AM
12:10AM
1:10PM
2:10PM
Section 01
Section 02
Section 03
Section 04
Section 05
Section 06
(Winkin)
(Blinkin)
(Winkin)
(Nod)
(Nod)
(Blinkin)
* Fill in all circles corresponding to the letters/numbers of your name, ID number, and section.
* Turn in ALL COLORED PAGES OF THIS EXAM and the COMPUTER SHEET.
GOOD LUCK --- and RTFQ
USEFUL FORMULAE
d= 1
p
∆λ = v
c
λ
L = R
L sun
R sun
d3 = m + m
1
2
P2
m1 d2
m2 = d1
L ∝ M4
t ms = 10 10yr ×
M
M sun
2
T
Tsun
–3
Rsch = 3 km (M/Mo)
4
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PART I: Multiple Choice: 40 questions, 2 points each. Select the best answer to
each of the questions below. Place your answer on the computer answer sheet
provided.
1. Most of the bright stars in the sky are bright because they are close (within 10 light years) to our
Sun.
a) correct
b) wrong: Most are intrinsically bright and lie far from the Sun.
c) wrong: Close means closer than 1 parsec.
d) wrong: This is true only for green stars.
e) wrong: Both changes c) and d) are needed.
2. Stars with the mass of our Sun produce energy primarily by the ________while they
are on the main sequence.
a) carbon-nitrogen (CN) cycle
b) proton-proton chain
c) triple alpha process
d) dynamo cycle
e) none of the above
3. What is the correct order of evolutionary stages for a star of 5 solar masses?
a) main sequence, brown dwarf
b) main sequence, giant, neutron star, white dwarf
c) red giant, white dwarf, main sequence, red giant
d) main sequence, giant, white dwarf
e) none of the above
4. Massive, spherical, tightly packed groupings of stars are called
a) associations.
b) open clusters.
c) globular clusters.
d) galaxies.
e) The Ringling Brothers' Circus.
5. M stars are ___________ in color
a) blue
b) blue to white
c) white to yellow
d) orange to red
e) taupe
6. The primary factor that determines the length of a star's main sequence lifetime and its position
on the main sequence is the star's
a) content of hydrogen.
b) distance from the Sun.
c) surface temperature.
d) luminosity.
e) mass.
Astro 150 Exam 2 Sample
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Astro 150 Exam 2 Sample
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7. The main sequence life of a star ends when
a) the star runs completely out of hydrogen.
b) hydrogen fusion exhausts hydrogen in the core.
c) helium fusion stops in the core.
d) the star cools down so much that fusion can no longer occur.
e) a planetary nebula is formed.
14. The spectral sequence is in the order of
a) the chemical abundances of the stars
b) increasing strengths of Balmer spectral lines
c) decreasing strengths of hydrogen absorption lines
d) decreasing temperature of the stars
e) alphabetical order
8. After the core hydrogen is depleted in a main sequence star, the core consists of
a) carbon.
b) deuterium.
c) nothing at all.
d) helium.
e) oxygen.
15. Given the apparent magnitude of a star one can calculate its luminosity by accounting for its
a) distance
b) spectral type
c) temperature
d) mass
e) radius
9. A magnitude difference of 3 implies a relative brightness of
a) 3
b) 3 x 2.5 = 7.5
c) 2.5 x 2.5 x 2.5 = 15.6
d) 100
e) 9
16. Most galaxies that we see display red shifts. This indicates
a) there is a lot of material between the Sun and the galaxies
b) most galaxies are moving away from us
c) the Sun is orbiting around the center of the Milky Way
d) the instruments we are using are in error
e) something, but we haven't learned in class what that could be
10. At what wavelength region do we find out the most about star formation?
a) gamma rays
b) ultraviolet
c) visible
d) infrared
e) radio
17. Which of the following sequences of spectral types place stars in order of decreasing mass?
a) O, B, A, F, G
b) M, K, G, A, B
c) A, B, F, G, K
d) K, G, F, B, A
e) B, K, M, G
11. Which of the following is the same for all stars along a vertical line in an HR diagram?
a) Temperature
b) Radius
c) Mass
d) Luminosity
e) Composition
18. A pulsar is an example of
a) a black hole.
b) a neutron star.
c) Little Green Men sending an extraterrestrial signal
d) a white dwarf.
e) a protostar.
12. Where are the stars with the largest radius found on an HR diagram?
a) At the upper left end of the main sequence.
b) At the lower right end of the main sequence.
c) At the upper right corner of the HR diagram.
d) At the lower left corner of the HR diagram.
e) Along the edges of the HR diagram.
19. What is the Jeans mass?
a) The mass required by a molecular cloud before it will absorb enough radiation to obscure
the light of stars on its far side.
b) The critical mass needed before a star can form from a molecular cloud.
c) The maximum possible mass of a white dwarf.
d) The weight of Sir James Jeans, in solar masses.
e) The mass a star must have before it can perform nuclear fusion in its core.
13. Which of the following types of binary stars is the least useful in learning about stars?
a) eclipsing binary stars
b) spectroscopic binaries
c) astrometric binaries
d) optical pairs
e) eclipsing spectroscopic binaries
20. The condensed remnant of a star with a mass of less than 12 solar masses that dies as
a supernova is
a) a G star.
b) a white dwarf.
c) a black hole.
d) a neutron star.
e) a white hole.
Astro 150 Exam 2 Sample
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Astro 150 Exam 2 Sample
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21. A good analogy to the physical explanation of how a neutron star can
appear as a pulsar is
a) a blinking neon sign.
b) a searchlight.
c) a greenhouse.
d) a metronome.
e) a traffic light.
28. Two stars are of the exact same spectral type, but Star A is 25 times as luminous as Star B.
The radius of Star A is
a) 25 times the radius of Star B
b) 5 times the radius of Star B
c) the same as Star B
d) 1/5 the radius of Star B
e) 1/25 the radius of Star B
22. Proof that star formation is occuring today is
a) we see short-lived massive stars
b) the Solar System was created 5,000 years ago
c) we see dust clouds near associations
d) both a) and b)
e) both a) and c)
29. Why are binary stars so important to astronomers?
a) With them, we can determine their centers of mass
b) Because they are so rare, the tell us something new about the universe
c) Because it is only from binary stars that we can directly determine stellar masses
d) Because it is only from binary stars that we can directly determine stellar ages
e) Because they give Ray Davis an opportunity to practice with Kepler's Laws
23.A ________ is so dense that its gravitational field keeps light from escaping
a) ballplayer's brain
b) supergiant
c) white dwarf
d) neutron star
e) black hole
30. Which of the following are possible triggers for star formation?
a) a nearby supernova.
b) collisions between molecular clouds.
c) a stellar wind from a nearby massive star.
d) all of the above.
e) none of the above
24. The distance (in parsecs) of a star whose parallax is 0.1 arc seconds is
a) 10 parsecs.
b) 1 parsec.
c) 0.1 parsec.
d) 3 parsecs.
e) not enough information given
31. The observed range of stellar luminosity (in units of solar luminosity) is
a) 1 (they are all the same).
b) 0.01 to 10.
c) 0.01 to 100.
d) 0.0001 to 1,000.
e) 0.0001 to 1,000,000.
25. Why do massive stars run out of hydrogen in their cores faster than less massive stars?
a) Their hydrogen fuses faster because of greater temperatures inside.
b) There is less hydrogen in their cores.
c) The cores of less massive stars contain a greater percentage of helium,
which slows hydrogen fusion.
d) The cores of less massive stars contain a lesser percentage of helium,
which slows hydrogen fusion.
e) this statement is false; more massive stars live longer than stars with smaller mass.
32. The Vogt-Russell theorem states that the properties of a star at any given age depend completely
upon the star's
a) luminosity and radius.
b) mass and luminosity.
c) mass, chemical composition, and radius.
d) radius, and chemical composition.
e) mass and chemical composition.
26. What percentage of stars lie on the main sequence?
a) 1%
b) 5%
c) 50%
d) 90%
e) 99%
27. Star A has a proper motion of 0.48"/yr, and Star B (nearby) has a proper motion of 0.12"/yr.
Which of the following is true?
a) Star A has a radial velocity 4 times larger than Star B
b) Star A has a radial velocity 4 times smaller than Star B
c) Stars A and B form a physical binary system
d) You can't compare their radial velocities without more information
e) You can't compare their proper motions without more information
33. The production of more and more massive chemical elements requires ever increasing
a) amounts of hydrogen.
b) helium.
c) iron.
d) time.
e) temperature.
34. For stars in a cluster, observed differences in apparent magnitude from one star to another are
due to differences in
a) luminosity.
b) chemical composition.
c) distance.
d) age.
e) popularity.
Astro 150 Exam 2 Sample
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35. The most massive main sequence star in a cluster is useful in determining a cluster's
a) mass.
b) age.
c) distance.
d) apparent magnitude.
e) velocity.
36. Helium burning requires a temperature of
a) 100 thousand K.
b) 1 million K.
c) 10 million K.
d) 100 million K.
e) 1 billion K
37. The final stellar remnant of a one solar mass star is a
a) white dwarf.
b) neutron star.
c) pulsar.
d) black hole.
e) main sequence star.
38. Neutron stars are thought to form from
a) 1 Msun stars.
b) 5 Msun stars.
c) 10 Msun stars.
d) 50 Msun stars.
e) all stars; mass has nothing to do with it.
39. Heavy elements which are mixed into the material from which new generations of stars may be
formed come primarily from
a) the big bang.
b) planetary nebulae.
c) supernovae.
d) spectroscopic binary stars.
e) Lead, South Dakota
40. If we are really unlucky and the Sun becomes a black hole, what will happen to the Earth's orbit
around the Sun
a) nothing; it will continue in its current orbit
b) it will rapidly fall into the black hole
c) it will be ripped apart by the strong gravity of the black hole
d) it will spiral into the black hole in a few months
e) the Earth will slowly spiral away from the Sun