Question 1

Ancient Chinese astronomers recorded the appearance of what phenomenon in 1054 C.E.?

Accepted Answer

Ancient Chinese astronomers recorded the appearance of a supernova in 1054 C.E., which was visible in daylight and remained visible for over a year. This event is now known as the Crab Nebula Supernova.

Question 2

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in 1054 C.E.?

Accepted Answer

The supernova explosion in our galaxy, known as SN 1054, was recorded by Chinese astronomers in the Sung Dynasty in 1054 C.E. It was visible even during daylight and was later discovered as the remnant called the Crab Nebula.

Question 3

The Crab Nebula (M1) is:

Accepted Answer

The Crab Nebula (M1) is a supernova remnant formed from a supernova explosion that was observed in 1054 AD.

Question 4

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

Accepted Answer

The first pulsars were discovered in the radio frequency range.

Question 5

The first pulsar was discovered by:

Accepted Answer

Jocelyn Bell, while working as a graduate student at Cambridge University, discovered the first pulsar in 1967 while analyzing radio telescope data. It was a landmark discovery in astronomy and earned her advisor, Anthony Hewish, a Nobel Prize.

Question 6

The discovery of the Crab Pulsar, with a period of only 1/30 s, ruled out a number of possible explanations for pulsars. These included all of the following EXCEPT ONE. Which one was the exception?

Accepted Answer

The discovery of the Crab Pulsar ruled out eclipsing binaries, variable stars, and rotating white dwarfs as possible explanations for pulsars, but did not rule out the possibility of rapidly shifting dark dust clouds as an explanation.

Question 7

The charged particles that emit the beams of electromagnetic radiation from a pulsar are believed to be:

Accepted Answer

Pulsars have extremely strong electric fields near their surface, which can lead to the creation of electron-positron pairs. The charged particles in the pulsar's magnetosphere then emit beams of electromagnetic radiation, including radio waves. This is known as the pulsar mechanism.

Question 8

How might Tycho's supernova of 1572 have been produced without leaving behind a pulsar?

Accepted Answer

Type Ia supernovae do not typically leave behind a pulsar, as they involve the explosion of a white dwarf star that has already exhausted its nuclear fuel and does not have enough mass to become a neutron star.

Question 9

Astronomers originally rejected the idea that white dwarfs could rotate fast enough to be responsible for pulsar radiation. However, they soon accepted the idea that neutron stars could produce pulsar radiation. Why this difference?

Accepted Answer

Neutron stars are smaller and even more dense than white dwarfs. Thus, they can rotate at tremendous rates without flying apart. This makes them more likely candidates for producing pulsar radiation.

Question 10

The difference between a nova and an x-ray burst is that a nova involves:

Accepted Answer

A nova involves an explosion on the surface of a white dwarf, where material from a companion star accretes onto the white dwarf's surface and triggers a thermonuclear explosion. An x-ray burst, on the other hand, involves an explosion on the surface of a neutron star, where material from a companion star falls onto the neutron star's surface and causes a sudden release of energy in the form of X-rays.

Question 11

What is the upper limit to the mass of a neutron star beyond which neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole?

Accepted Answer

The upper limit to the mass of a neutron star is around 3 solar masses (3 MS). Beyond this, the neutron degeneracy pressure cannot withstand the force of gravity and the neutron star is crushed out of existence into a black hole. This limit is known as the Tolman-Oppenheimer-Volkoff limit. Therefore, the correct option is D.

Question 12

How long does a short gamma ray burst (short GRB) typically last?

Accepted Answer

Short gamma ray bursts typically last less than 2 seconds, distinguishing them from long gamma ray bursts which can last from a few seconds to several minutes.

Question 13

What event is now known to be a source of short GRBs?

Accepted Answer

The merger of two neutron stars is now known to be a source of short GRBs (gamma-ray bursts) as observed by various telescopes and instruments. This event releases an enormous amount of energy and produces a short burst of gamma rays, followed by an afterglow in other wavelengths of the electromagnetic spectrum.

Question 14

How much mass is lost when two 1-M_ε neutron stars merge?

Accepted Answer

When two neutron stars merge, about 1% of the mass is converted into energy according to Einstein's mass-energy equivalence principle (E=mc^2). This mass loss is primarily emitted as gravitational waves.

Question 15

What happens to the mass ejected into space when two neutron stars merge?

Accepted Answer

When two neutron stars merge, a kilonova occurs, which results in the ejection of a significant amount of matter into space. This matter is rich in heavy elements such as gold, platinum, and uranium, which are produced through a process known as rapid neutron capture, or the r-process. Therefore, the correct answer is D, "Large quantities of heavy elements such as gold and uranium are produced."

Question 16

How are large amounts of heavy elements, such as gold, silver, and uranium, known to be formed?

Accepted Answer

Large amounts of heavy elements, such as gold, silver, and uranium, are known to be formed in the merger of two neutron stars. The extreme conditions during the collision cause the rapid neutron capture process, also known as the r-process, which produces heavy elements beyond iron.

Question 17

What is "special" about the special theory of relativity?

Accepted Answer

The special theory of relativity, proposed by Albert Einstein in 1905, specifically addresses the physics of objects moving at constant velocity relative to each other, including those moving at speeds close to the speed of light. It does not deal with accelerated motion or gravity; those are the realm of the general theory of relativity.

Question 18

There is an old joke about telling the police officer who stops you for running a red light that you were moving so fast that the light looked green. Take red to have a wavelength of 650 nm and green 500 nm. How fast WOULD you have to be moving (c = speed of light)? Is this relativistic?

Accepted Answer

To observe the red light as green due to the Doppler effect, the required speed is relativistic. The shift from 650 nm to 500 nm due to relativistic Doppler effect implies a significant fraction of the speed of light, around 64% of c, confirming the relativistic nature of the scenario.

Question 19

You are flying your spacecraft on a parallel course with another spacecraft and at the same speed. You are both moving past Earth at an appreciable fraction of the speed of light. Which one of the following statements correctly describes the relationship between your clock and the clock in the other spacecraft?

Accepted Answer

According to the theory of relativity, time dilation occurs when an observer is moving at a significant fraction of the speed of light relative to another observer. However, in this scenario, both spacecraft are moving at the same speed, so there is no relative motion between the two. Therefore, each observer will see the other clock running at the same rate as their own clock. Hence, option B is correct.

Question 20

Suppose you are in the Space Shuttle in orbit around Earth at a speed of 7 km/s, and at some particular time your direction of travel is straight toward the Sun. The speed of light in a vacuum is 300,000 km/s. What speed will you measure for the light from the Sun?

Accepted Answer

According to the theory of relativity, the speed of light in a vacuum is always measured as the same value, 300,000 km/s, regardless of the motion of the source or the observer.

Quiz 21: Stellar Remnants: Neutron Stars and Black Holes

Ancient Chinese astronomers recorded the appearance of what phenomenon in 1054 C.E.?

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in 1054 C.E.?

The Crab Nebula (M1) is:

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

The first pulsar was discovered by:

The discovery of the Crab Pulsar, with a period of only 1/30 s, ruled out a number of possible explanations for pulsars. These included all of the following EXCEPT ONE. Which one was the exception?

The charged particles that emit the beams of electromagnetic radiation from a pulsar are believed to be:

How might Tycho's supernova of 1572 have been produced without leaving behind a pulsar?

Astronomers originally rejected the idea that white dwarfs could rotate fast enough to be responsible for pulsar radiation. However, they soon accepted the idea that neutron stars could produce pulsar radiation. Why this difference?

The difference between a nova and an x-ray burst is that a nova involves:

What is the upper limit to the mass of a neutron star beyond which neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole?

How long does a short gamma ray burst (short GRB) typically last?

What event is now known to be a source of short GRBs?

How much mass is lost when two 1-M_ε neutron stars merge?

What happens to the mass ejected into space when two neutron stars merge?

How are large amounts of heavy elements, such as gold, silver, and uranium, known to be formed?

What is "special" about the special theory of relativity?

There is an old joke about telling the police officer who stops you for running a red light that you were moving so fast that the light looked green. Take red to have a wavelength of 650 nm and green 500 nm. How fast WOULD you have to be moving (c = speed of light) ? Is this relativistic?

Suppose you are in the Space Shuttle in orbit around Earth at a speed of 7 km/s, and at some particular time your direction of travel is straight toward the Sun. The speed of light in a vacuum is 300,000 km/s. What speed will you measure for the light from the Sun?

Quiz 21: Stellar Remnants: Neutron Stars and Black Holes

Ancient Chinese astronomers recorded the appearance of what phenomenon in 1054 C.E.?

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in 1054 C.E.?

The Crab Nebula (M1) is:

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

The first pulsar was discovered by:

The discovery of the Crab Pulsar, with a period of only 1/30 s, ruled out a number of possible explanations for pulsars. These included all of the following EXCEPT ONE. Which one was the exception?

The charged particles that emit the beams of electromagnetic radiation from a pulsar are believed to be:

How might Tycho's supernova of 1572 have been produced without leaving behind a pulsar?

Astronomers originally rejected the idea that white dwarfs could rotate fast enough to be responsible for pulsar radiation. However, they soon accepted the idea that neutron stars could produce pulsar radiation. Why this difference?

The difference between a nova and an x-ray burst is that a nova involves:

What is the upper limit to the mass of a neutron star beyond which neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole?

How long does a short gamma ray burst (short GRB) typically last?

What event is now known to be a source of short GRBs?

How much mass is lost when two 1-Mε neutron stars merge?

What happens to the mass ejected into space when two neutron stars merge?

How are large amounts of heavy elements, such as gold, silver, and uranium, known to be formed?

What is "special" about the special theory of relativity?

There is an old joke about telling the police officer who stops you for running a red light that you were moving so fast that the light looked green. Take red to have a wavelength of 650 nm and green 500 nm. How fast WOULD you have to be moving (c = speed of light) ? Is this relativistic?

Suppose you are in the Space Shuttle in orbit around Earth at a speed of 7 km/s, and at some particular time your direction of travel is straight toward the Sun. The speed of light in a vacuum is 300,000 km/s. What speed will you measure for the light from the Sun?

How much mass is lost when two 1-M_ε neutron stars merge?