Question 1

Stars with masses between 8 and 14 times the mass of the Sun will end their lives as neutron stars.

Accepted Answer

False

Question 2

Because light cannot escape from a black hole,there is no evidence that they actually exist.

Accepted Answer

While we cannot directly observe black holes, there is evidence for their existence through their effects on surrounding matter and gravitational waves observed by advanced detectors like LIGO.

Question 3

In 1054,the imperial astronomer to the Chinese court recorded observing a "guest star" in the sky.We know now that this "guest star" was a supernova explosion within our Galaxy.

Accepted Answer

This statement is true. The "guest star" observed in 1054 was indeed a supernova explosion within our Galaxy, which resulted in the formation of the Crab Nebula.

Question 4

In general,a Type Ia supernova is brighter than a Type II supernova.

Accepted Answer

Type Ia supernovae are caused by white dwarf stars and have a very consistent brightness, making them very useful for cosmological distance measurements. Type II supernovae are caused by the collapse of massive stars and can have varying brightness levels. Therefore, on average, Type Ia supernovae are brighter than Type II supernovae.

Question 5

Type Ia supernovae are generally brighter than Type II supernovae.

Accepted Answer

Type Ia supernovae are generally brighter than Type II supernovae because they involve a complete disruption of the white dwarf star, while Type II supernovae are caused by the core collapse of massive stars.

Question 6

After the core collapse and bounce in a supernova explosion,neutrinos pour out of the developing neutron star to propel the shock wave outward.

Accepted Answer

Neutrinos are produced in huge numbers during the core collapse of a supernova and as they interact weakly with matter, they can escape easily out of the collapsing core. These neutrinos carry away a significant fraction of the gravitational binding energy of the neutron star that forms after the core collapse. These neutrinos produce pressure on the newly forming neutron star, and this also helps in driving the shock wave outward.

Question 7

Every year,two or three supernovae are seen within our own Galaxy.

Accepted Answer

On average, supernovae in our own Galaxy are much rarer, with estimates suggesting one occurs about every 50 years or so. However, due to dust and gas obscuring our view, many are not directly observable from Earth.

Question 8

A Type Ia supernova is thought to result from the thermonuclear explosion of a white dwarf star in a close binary system with a larger companion star.

Accepted Answer

This is a widely accepted theory among astronomers based on observations and models.

Question 9

When a star becomes a black hole,its gravitational pull becomes stronger.

Accepted Answer

The gravitational pull of a star at a given distance remains the same after it becomes a black hole; what changes is that the mass is now concentrated in a much smaller volume, allowing for stronger gravitational effects closer to the surface.

Question 10

Supermassive black holes are generally thought to develop in the relatively empty space between galaxies.

Accepted Answer

Supermassive black holes are known to reside at the center of galaxies, including our own Milky Way. They are thought to form from the collapse of massive clouds of gas and dust, and can grow through the accretion of matter from their surroundings.

Question 11

In general,an isolated pulsar speeds up as it ages,so its pulse period decreases.

Accepted Answer

As a pulsar ages, it loses energy and spins more slowly, so its pulse period actually increases over time.

Question 12

A supergiant star can keep adding shells to its core "onion" structure until it produces uranium as a byproduct.

Accepted Answer

Supergiant stars can add shells in their core structure and produce elements up to iron through nuclear fusion, but elements heavier than iron, like uranium, are generally formed through other processes such as supernova nucleosynthesis or neutron star mergers, not by fusion in a star's core.

Question 13

The event horizon surrounding a black hole describes the "surface" in space where the escape velocity equals the speed of light.

Accepted Answer

This is a correct statement. The event horizon is the point of no return for anything that enters a black hole, as the escape velocity surpasses the speed of light at this point.

Question 14

X-ray bursters,like novae,are thought to involve close binaries whose stars are engaged in mass transfer.

Accepted Answer

X-ray bursters are indeed thought to involve close binaries where one star is a neutron star or a black hole and the other star is an ordinary star that is transferring mass onto the compact object. As the accretion disk around the compact object grows, it eventually becomes unstable and a burst of X-rays is released.

Question 15

Jocelyn Bell,a young graduate student at Cambridge University in 1967,and her colleagues detected the first pulsar using an array of radio antennas.

Accepted Answer

This statement is true. Jocelyn Bell and her colleagues did indeed detect the first pulsar in 1967 using radio antennas at Cambridge University.

Question 16

The evolutionary stage of a very large star that lasts the longest is when it is going through hydrogen fusion.

Accepted Answer

When a very large star is in the stage of hydrogen fusion, it is burning its hydrogen fuel, which is the longest stage of a star's life cycle. This stage can last millions to billions of years, depending on the size and mass of the star.

Question 17

All supernova remnants that have been observed are spherical in shape.

Accepted Answer

While many supernova remnants are indeed roughly spherical in shape, there are some that have more complex and irregular shapes, such as the Crab Nebula.

Question 18

When a star with an initial mass greater than about 8 solar masses nears the end of its life,it becomes a red supergiant and its energy comes from a series of concentric fusing shells.

Accepted Answer

This is true. As a star with an initial mass greater than about 8 solar masses begins to exhaust the hydrogen in its core, it will begin to fuse helium and other elements in concentric shells surrounding the core. This process will continue until the star reaches iron in its core, at which point it will undergo a supernova explosion.

Question 19

The Schwarzschild radius describes the maximum radius that a white dwarf can have.

Accepted Answer

The Schwarzschild radius describes the maximum radius that a non-rotating black hole can have, not a white dwarf. The radius of a white dwarf is determined by its mass and composition.

Question 20

All black holes have the same amount of gravitational force.

Accepted Answer

The gravitational force of a black hole depends on its mass. The greater the mass, the greater the gravitational force.

Quiz 12: Predicting the Violent End of the Largest Stars