Knowledge Showcase – Midterm Review
Cosmic Search: Little Green Men, White Dwarfs or Pulsars? Jocelyn Bell Burnell
1. What was Jocelyn Bell trying to research when she came across her “bit of scruff”?
2. Describe the telescope and data recording system Jocelyn Bell was using when she
collected the “bit of scruff”?
3. The source of the radio waves that Bell was observing raised 4 minutes earlier every
day. What is the significance of this observation?
Solar and Sidereal Day
4. The Earth orbits the Sun in a counterclockwise direction once every 365 days. How
many degrees does Earth move along its orbit in one day?
5. How long does it take Earth to rotate exactly 360°?
6. The average length of a solar day is
7. A sidereal day is defined as
8. Why is a solar day longer than a sidereal day?
The Discovery of the Neutron Star
9. Who discovered the first pulsar?
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Knowledge Showcase – Midterm Review
10. What was the significance of the discovery of the pulsars in the Crab Nebula and the
Vela Supernova Remnant?
11. Which of the following is NOT a basic property of neutron stars?
a. Strong gravitational field
b. Strong magnetic field
c. Extremely high density
d. Extremely large volume
12. When radio astronomers view pulsars, they are really viewing
13. True/False: Neutron stars are always pulsars (and explain why)
14. Which of the following is NOT a characteristic of
millisecond pulsars?
a. They are relatively old.
b. They are smaller than normal pulsars.
c. They spin more rapidly than normal pulsars.
d. They make very accurate timekeepers.
15. The Crab pulsar was the first _______________ pulsar to be
discovered.
16. Pulsars have been viewed at what wavelengths?
Pulsars and Neutron Stars
17. What causes the radio pulses of a pulsar
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18. From an observational standpoint, what is a pulsar? From a theoretical standpoint, what
is s pulsar? (COMPARE WHAT IS OBSERVED TO WHAT IT ACTUALLY IS)
19. Which statement about pulsars is NOT thought to be true?
a. All pulsars are neutron stars, but not all neutron stars are pulsars
b. A pulsar must have a very strong magnetic field and rotate quite rapidly
c. Pulsars can form only in close binary systems
d. Pulsars are kept from collapsing by neutron degeneracy pressure.
Celestial Coordinates
20. What is the celestial sphere?
21. What does the RA and Dec of a pulsar tell us?
Normal Matter, Interior of Stars, and Hydrostatic Equilibrium
22. Which of the following statements about electrons in NOT true?
a. An electron has a negative electrical charge.
b. Electrons orbit the nucleus rather like planets orbiting the Sun
c. Within the atom, an electron can have only particular energies (live in specific
energy levels at specific distances away from the nucleus)
d. Electrons can jump between energy levels in an atom only if they receive or give
up an amount of energy equal to the difference in energy between the energy
levels.
23. At extremely high temperatures (e.g. millions of degrees), which of the following best
describes the phase of matter?
a. A gas of rapidly moving molecules
b. A plasma consisting of positively charged ions and free electrons.
c. A gas consisting of individual, neutron atoms, but no molecules
d. Electron or neutron degenerate matter.
24. When an atom loses an electron, it becomes _________________________
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Knowledge Showcase – Midterm Review
25. The loss of an electron from a neutral helium atom results in
26. What happens to the volume and pressure of a system composed of “normal matter”
(non-degenerate) when thermal energy is added?
27. The equation of state for an ideal gas can be described by which three parameters
28. The energy attributed to an object by virtue of its motion is known as
29. Radiative energy is
30. What does temperature measure
31. What do we mean when we say that the Sun is in hydrostatic equilibrium?
32. What would happen to the volume of our Sun if it were to suddenly increase its mass to
1.2 Msun?
Compact Stars and Degenerate Matter
33. Degeneracy pressure is the source of the pressure that stops the crush of gravity in what
type of objects (make a list and describe the type of pressure)
34. White dwarfs are so called because they
35. A teaspoonful of white dwarf material on Earth would weigh
36. Why is there an upper limit to the mass of a white dwarf?
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37. What is the ultimate fate of an isolated white dwarf?
38. Suppose a white dwarf is gaining mass because of accretion in a binary system. What
happens if the mass reaches the Chandrasekhar limit?
39. How does a 1.2 Msun white dwarf compare to a 1.0 Msun white dwarf?
40. After a massive-star supernova, what is left behind?
41. What is the upper limit to the mass of a neutron star?
42. A teaspoon full of neutron star material on Earth would weigh
43. Describe the size (diameter) of a neutron star in terms of familiar sizes (Ex objects or
places).
44. What is the ultimate fate of an isolated pulsar?
Interiors of Neutron Stars
45. Neutron stars have unique interior structures. Describe the interior structure.
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46. What is thought to be the cause of a glitch?
47. Describe the evidence that a neutron star contains a neutron superfluid interior.
48. A magnetar is a
49. Use the space below to draw and label a diagram of a neutron star and the earth to
represent the observation of a pulsar. You must include the neutron star, its axis of
rotation, its magnetic axis, the radio beams, and the earth. (5 points)
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Searching for and Analyzing Pulsars (locating information)
1. Put a box around the 4 subplots that you are responsible for scoring, label with the plot name
and score each using the 1, 2, 3 score guide. (12 points)
2. What is the candidate name of this object?
3. What is the period of this pulsar?
4. How many times does this pulsar rotate in 1 second?
5. What band of radio frequencies was detected by the GBT to generate this plot?
6. State the dispersion measure for this pulsar? What information does this provide? (2 points)
7. State the Reduced χ2 value for the DM. What does this tell us? (2 points)
8. List the RA and Dec of this pulsar. (2 points)
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