Download Sample Exam 2

Sample Exam
On the real exam, there will be 30 questions, worth 4 points each, and 80 points divided among several short and “longer”
answer questions, similar to exam 1. This sample does not have exactly the same numbers of questions as the real exam.
Email me if you think you have found a typo or an error.
1.
A star which periodically appears in the sky (visible to the naked eye)
A. binary system of a white dwarf and a red giant
companion.
D.
B. eclipsing binary.
E.
C. binary system of a neutron star and a red giant
every ten years is most likely a(n)
companion.
spectroscopic binary.
optical double.
2.
The Schwarzschild radius of an object is
A. the distance from its center at which nuclear fusion ceases.
B. the radius of a mass at which its escape velocity equals the speed of light.
C. the distance from its surface at which an orbiting companion will be broken apart.
D. the maximum radius a white dwarf can have before it collapses.
3.
Which astronomer is the H of the H-R diagram?
A. Stephen Hawking
B. Harlow Shapley
C. Edwin Hubble
D. William Herschel
E. Ejnar Hertzsprung
4.
Which of the following is true for all M-class stars? They all
A. fuse hydrogen into helium.
B. have low luminosities.
C. have a low surface temperature.
D. have a low mass.
E. All of the above.
5.
How far away is a star which shows a parallax angle of 0.5 arcseconds?
A. 1 parsec
D. 4 parsecs
B. 2 parsecs
E. 0.25 parsecs
C. 0.5 parsecs
6.
Which of these stages will the future Sun not evolve through?
A. Supernova
B. Planetary Nebula
C. White Dwarf
D. Red Giant
7.
If a star is about twice as hot as our Sun, but is about 64 times more luminous, we can conclude that it must be ______
the Sun.
A. smaller
B. larger
C. the same size as
8.
When a photon interacts with an atom, what change occurs in the atom?
A. The nucleus begins to glow.
B. An electron changes its orbital.
C. The photon becomes trapped in orbit.
D. The atomic number increases.
9.
You look at a tube of excited Helium gas with a diffraction grating. You notice purple, blue, yellow, and red lines, but
the yellow line is the brightest. The most likely explanation for this is that
A. the yellow light is actually the only light from the Helium gas, the other colors are from small amounts of other
gases contaminating the tube.
B. the photons that make up this line are the most energetic.
C. there are more yellow photons being emitted by the electrons in the gas.
D. your eyes are more sensitive to the yellow light.
10. Late in its evolution, the Sun will become a white dwarf with a radius about 100 times smaller than its current radius.
The volume of the Sun today is approximately ______ times larger than its future volume.
A. 100
B. 103
C. 104
D. 106
E. 108
11. What kind of celestial observation would be best done using an infrared telescope?
A. Measuring the thermal radiation from a star.
B. Measuring the emission from electrons spiraling around magnetic fields in a pulsar.
C. Measuring the chemical composition of a planet's atmosphere.
D. Measuring the dust glowing in a supernova remnant.
12. What do you get when you divide 104 by 107 ? 10E where E is
A. -7
B. -3
C. 0
D. 3
E. 11
13. If an interstellar cloud is emitting light with a wavelength 3 times longer than a nearby star, the frequency from the
cloud must be ____ times the frequency from the star.
A. 9
B. 1/9
C. 3
D. 1/3
14. Describing an atom’s orbitals as being quantized refers to the fact that
A. the atom is made of individual electrons, protons, and neutrons.
B. there are the same number of electrons as protons.
C. the electron can oscillate only with certain discrete patterns.
D. the electron’s electric charge has a single fixed value.
15. Which of the following is NOT a reason that astronomers seek to build larger telescopes?
A. Larger telescopes can resolve greater detail.
B. Larger telescope collect more photons.
C. Larger telescopes can detect fainter objects.
D. Larger telescopes are less affected by the Earth’s atmosphere.
16. The Sun’s surface temperature is about 5800 K, and the peak of its spectrum lies in the yellow-green part of the visible
spectrum. The spectrum of the star Rigel, with a surface temperature of about 11,000 K, could be best described as
peaking near _________ part of the spectrum.
A. the infrared
D. gamma ray
B. red (visible)
E. ultraviolet
C. green (visible)
17. If you double the kinetic energy of an object, its ____________ temperature doubles.
A. Farenheit
B. Celsius
C. Kelvin
D. All of the above
18. Stellar spectra show dark lines against a continuum background. We can conclude that stars
A. are composed entirely of hydrogen.
B. have a hot interior shining through hotter, high density gas.
C. have a cool interior shining through cooler, high density gas.
D. have a hot interior shining through cooler, low density gas.
E. have a cool interior surrounded by hotter, low density gas.
19. Suppose we detect a Sodium line at 589 nm (from an electron transition between levels 2 and 1) in the spectrum of a
star with a surface temperature of 4000 K. In light from a star with a surface temperature of 8000 K, what would the
wavelength of the transition between levels 2 and 1 in Sodium be?
A. 294.5 nm (or half)
B. 589 nm
C. 1178 nm
(or twice as much)
D. 2356 nm
(or four times as much)
20. Studying the Sun’s flares, sunspots and coronal mass ejections is important because
A. the activity of the Sun affects satellites orbiting Earth and Earth’s atmosphere.
B. the same activities don’t happen on other stars.
C. the activity indicates that Sun is close to moving off of the main sequence.
D. the Earth’s magnetic field also reverses on an 11 year cycle.
21. In a visual binary system, star A is located 5 AU from the barycenter (center of mass of the binary system), while star B
lies 25 AU farther out on the opposite side. We can thus conclude that:
A. star B must move five times slower than A.
B. star B must be five times more massive than star A.
C. star A must be five times more massive than star B.
D. star A would show a five times larger doppler shift in its spectra.
22. Which type of atom listed below requires the greatest temperature to undergo nuclear fusion?
A. Carbon (atomic number 6)
B. Silicon (atomic number 14)
C. Oxygen (atomic number 8)
D. Helium (atomic number 2)
23. A star that is cool and very luminous must have
A. a very large radius.
B. a very small radius.
C. a very small mass.
D. a very great distance.
E. a very low velocity.
24. Yellow giants differ from yellow main sequence stars like our Sun because they are fusing ____ in their temporarily
stable cores.
A. Hydrogen
B. Helium
C. Carbon
D. Iron
25. The Chandrasekhar Limit is
A. the fastest a white dwarf or neutron star can rotate.
B. the closest you can get to a black hole without falling in.
C. the most mass a brown dwarf can have.
D. the most mass a white dwarf can have.
E. the least mass a white dwarf can have.
26. A good way to determine the age of a stellar cluster would be to
A. count the number of supernovae going off.
B. make an H-R diagram and look at how far up the main sequence there are stars.
C. determine the orbital parameters of any binary systems in the cluster.
D. use spectroscopy to determine the ratio of isotopes of Carbon in the stars’ atmospheres and apply radioactive dating
techniques.
27. Which of the following has a radius closest to that of a neutron star?
A. The Sun
B. A basketball
C. A small city
D. The Earth
E. A red giant
28. Consider the formation of Type Ia and Type II (core-collapse) supernovae. Which is true?
A. Type Ia supernovae show no hydrogen because they come from the explosion of a white dwarf.
B. Type II supernovae always produce black holes as the stellar remnant.
C. Type Ia supernovae can produce a white dwarf, neutron star, or black hole.
D. Pulsars only form in supernovae in binaries because they need the orbital angular momentum to spin up to high
rotational speeds.
Short/Long Answer Questions
(1) Sketch the internal structure of a 10, 1, and .5 solar mass star, indicating the core, radiative, and convection zones.
(2) Explain the conservation of energy that occurs as a typical roller coaster operates.
(3) Explain the difference between energy production in the Sun and in a 20 solar mass star.
(4) Describe two different ways to measure the distance to a star.
(5) Explain the purpose and primary limitations of a telescope. Is magnification important?