NAME _____________________________ ID # ____________ LAB # ________
Astronomy 1001 Dr. Thomas W. Jones
Midterm #2 Fall 2000
Read Instructions Carefully:
The short answer questions of this exam are graded by more than one person, so it is imperative that your NAME BE LEGIBLY WRITTEN ON EACH PAGE OF THE ESSAY PORTION!
1. MARK THE ANSWERS YOU CHOOSE ON THIS TEST AS IT IS YOUR ONLY
OPPORTUNITY TO CHECK WHICH ANSWERS YOU GOT RIGHT OR
WRONG. This will not be done for you at a later time in the departmental office.
Exams will be returned to the alphabetical boxes in the North wall of the Physics
building approximately 3-4 days after the exam.
2. Print your NAME, ID # and SECTION # on your answer sheet where appropriate. Your
SECTION # should read 03. All three items are necessary for the proper scoring and
computer transfer of your scores.
3. Use a pencil, make your marks dark and neat, and erase thoroughly.
4. There is only one answer to each question. Choose the best answer.
5. You may use this test for scratch paper.
6. One page (two sides) of notes is allowed for the exam.
I. Multiple Choice (2 pts. each)
1. A displacement of the dark lines in a star's spectrum toward longer wavelengths usually indicates that
a) the star is approaching Earth
b) Earth is approaching the star
c) the star is moving away from Earth
d) the star is rapidly rotating
e) the star is red
2. The dark-line spectrum of the sun is caused by
a) intense sunspot activity
b) gravitation of the moon
c) radiation emitted from the dark side of the sun
d) a dense intervening cloud of interplanetary dust and gas
e) absorption of radiation by the solar atmosphere
3. The position of a main-sequence star in the HR diagram is determined by its initial
a) velocity b) temperature c) angular momentum d) luminosity e) mass
4. The layer in the Sun from which most visible light comes is the solar
a) chromosphere b) core c) photosphere d) spectral zone e) corona
5. Normal stars age and evolve because they
a) gradually use up their nuclear fuel
b) cool off with time
c) form planets
d) collide with other stars
e) gradually use up their rotational energy
6. A white dwarf star does not collapse further because
a) normal gas pressure balances gravity
b) degenerate electron pressure supports it
c) radiation pressure supports it
d) rotates rapidly
e) pulsates energetically
7. The most important relationship established by the H-R diagram is indirect evidence that
a) stars all have the same mass
b) stars are all born in the galactic halo
c) galaxies collide often
d) the majority of stars derive their luminosities from hydrogen fusion
e) sunspots appear at high latitudes early in a sunspot cycle
8. A normal star becomes a red giant soon after
a) the central core of the star has been converted into helium
b) its core has collapsed in a supernova explosion
c) most of its hydrogen has been converted to helium and other elements
d) the star's central temperature has risen high enough for nuclear reactions
e) nuclear reactions have formed a certain amount of carbon, nitrogen and
9. Five hot glowing bodies (maybe stars) have the colors listed below. Which is probably hottest?
a) orange b) green c) red d) yellow e) blue
10. Of the following forms of electromagnetic energy, that which consists of photons of the lowest energy is
a) X-rays b) visible light c) infrared light d) radio waves e) ultraviolet light
11. 1.4 solar masses is the maximum mass for
a) main sequence stars b) black holes c) neutron stars d) white dwarfs e) gas giant planets
12. Most gold, platinum, and other heavy nuclei in the universe were probably produced by or in
a) the disintegration of radioactive elements
b) the proton-proton reaction
c) supernova explosions
d) solar flares
e) nuclear fission
13. The total main sequence lifetime of a star like the Sun is about _____ years.
a) 100 million b) 1x109 c) 10 billion d) 5,000,000,000 e) 5x1012
14. The glowing filament of an electric bulb gives a(an)
a) bright-line spectrum
b) absorption spectrum
c) dark-line spectrum
d) continuous spectrum
e) Fraunhofer spectrum
15. Which of these types of electromagnetic radiation has the shortest wavelength?
a) x-rays b) visible orange light c) radio waves d) infrared e) microwaves
16. A star comparable in mass to the sun, after it has become a red giant, will
a) collapse to form a neutron star
b) move along a track parallel to the main sequence on the H-R diagram
c) become a quasar
d) join Population II
e) eject its outer layers to form a planetary nebula
17. For a star to remain in equilibrium, the inward force of gravity must be balanced inside the star by
a) cosmic rays from the surface
b) pressure in the interior
c) neutrino flux
d) expansion of the helium core
e) pulsations in the interior
18. During the formation of a star, contraction stops when
a) the star collapses to a black hole
b) hydrogen burning becomes the dominant energy source
c) the star becomes a white dwarf
d) helium burning becomes the dominant energy source
e) the star begins to pulsate
19. A star of 10 solar masses eventually
a) fragments into planets
b) forms a planetary nebula
c) becomes a white dwarf
d) explodes in a supernova event
e) becomes a quasar
20. We can best estimate the size of a star from measurements of its _____________
a) mass and spectral type
b) distance and surface temperature
c) absolute luminosity and surface temperature
d) mass and distance
e) spectral type and distance
NAME _____________________________ ID # ____________ LAB # ________
Astronomy 1001 Dr. Thomas W. Jones
Midterm #2 Fall 2000
II Short Answers (5 pts. each)
1. Briefly outline the main life stages of a star similar to the sun. Include a statement about its origin and its end point as well as a summary of how it produces energy to shine during each stage in between.
2. Briefly explain how the H-R diagram observed for a cluster of stars can be used to determine its distance and age. What key property of stellar evolution enables astronomers to use this method?