Worksheet: Neutron Stars

In this worksheet, we will practice determining the compositional and kinematic properties of neutron stars.

Q1:

Which of the following statements is the correct definition of a pulsar?

  • AA pulsar is a rotating black hole that emits short bursts of radio-wave radiation at regular intervals.
  • BA pulsar is a nonrotating neutron star that emits short bursts of radio-wave radiation at regular intervals.
  • CA pulsar is a rotating neutron star that emits short bursts of radio-wave radiation at regular intervals.
  • DA pulsar is a white dwarf star that emits short bursts of radio-wave radiation at regular intervals.
  • EA pulsar is a main sequence star that emits short bursts of radio-wave radiation at random.

Q2:

A neutron star has a radius of 10.0 km and a mass of 2 . 4 0 š‘š āŠ™ . What is the average density of the neutron star? Use a value of 1 . 9 9 Ɨ 1 0 ļŠ© ļŠ¦ k g for the mass of the Sun. Give your answer to 3 significant figures.

  • A 4 . 7 5 Ɨ 1 0 ļŠ§ ļŠ­ kg/m3
  • B 1 . 9 9 Ɨ 1 0 ļŠ§ ļŠ® kg/m3
  • C 4 . 7 8 Ɨ 1 0 ļŠ§ ļŠ® kg/m3
  • D 3 . 8 0 Ɨ 1 0 ļŠ§ ļŠ­ kg/m3
  • E 1 . 1 4 Ɨ 1 0 ļŠ§ ļŠ® kg/m3

Q3:

A neutron star has a mass of 1 . 8 1 š‘š āŠ™ . Assuming that Newtonian gravity applies, at what radius from the neutron star would the acceleration due to gravity from the star be equal to that on the surface of Earth? Use a value of 1 . 9 9 Ɨ 1 0 ļŠ© ļŠ¦ kg for the mass of the Sun, 6 . 6 7 Ɨ 1 0 ļŠ± ļŠ§ ļŠ§ m3/kgā‹…s2 for the universal gravitational constant, and 1 . 5 0 Ɨ 1 0 ļŠ§ ļŠ§ m for the length of 1 AU. Give your answer in astronomical units to 3 significant figures.

Q4:

A neutron star has a radius of 11.2 km and a mass of 2 . 9 š‘š āŠ™ . Assuming that the neutron star has a uniform density, what volume of neutron star matter would have the same mass as Mount Everest? Use a value of 1 . 9 9 Ɨ 1 0 ļŠ© ļŠ¦ kg for the mass of the Sun and 1 . 5 0 Ɨ 1 0 ļŠ§ ļŠŖ kg for the approximate mass of Mount Everest. Give your answer to 3 significant figures.

  • A 1 . 5 3 Ɨ 1 0 ļŠ± ļŠŖ m3
  • B 4 . 4 4 Ɨ 1 0 ļŠ± ļŠŖ m3
  • C 1 . 0 6 Ɨ 1 0 ļŠ± ļŠØ m3
  • D 5 . 5 4 Ɨ 1 0 ļŠ± ļŠ« m3
  • E 3 . 6 5 Ɨ 1 0 ļŠ± ļŠ« m3

Q5:

Which of the following statements is the correct definition of a magnetar?

  • AA magnetar is a neutron star with only one magnetic pole.
  • BA magnetar is a neutron star with tens or hundreds of magnetic poles.
  • CA magnetar is a neutron star with visible magnetic field lines.
  • DA magnetar is a neutron star with an extremely powerful magnetic field.
  • EA magnetar is a type of neutron star that consists only of ferromagnetic elements.

Q6:

A neutron star has a mass of 1 . 9 7 š‘š āŠ™ . What is the acceleration due to gravity of the neutron star at a radius of 1 AU from the neutron star? Use a value of 1 . 9 9 Ɨ 1 0 ļŠ© ļŠ¦ kg for the mass of the Sun, 6 . 6 7 Ɨ 1 0 ļŠ± ļŠ§ ļŠ§ m3/kgā‹…s2 for the universal gravitational constant, and 1 . 5 0 Ɨ 1 0 ļŠ§ ļŠ§ m for the length of 1 AU. Give your answer to 3 significant figures.

Q7:

The graph shows the intensity of the radio waves received from a pulsar against time.

What is the period of rotation of the pulsar?

Q8:

The graph shows the intensity of the radio waves received from a pulsar against time.

What is the period of rotation of the pulsar?

How many times does the pulsar rotate each second?

Q9:

The graph shows the intensity of the radio waves received from a pulsar against time. What is the period of rotation of the pulsar?

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