Question 1

Using the Hubble Space Telescope,you discover a Cepheid variable star in a nearby galaxy that has a period of 10 days and an apparent magnitude of 20.If nearby Cepheids follow a period-luminosity relationship that says the luminosity of the star is  then what is this Cepheid's absolute magnitude and distance? Note that the Sun's absolute magnitude is 5.

Accepted Answer

The answer of Using the Hubble Space Telescope,you discover a...

Question 2

When the core of a massive star collapses,a neutron star forms because

Accepted Answer

When the core of a massive star collapses, protons and electrons combine to form neutrons, minimizing electromagnetic forces and resulting in a neutron star.

Question 3

Essentially all the elements heavier than iron in our galaxy were formed

Accepted Answer

Elements heavier than iron require more energy to fuse together than is released in the process, so they cannot be formed via nuclear fusion in stars. Instead, these elements are formed in supernova explosions, where the high energy and pressure from the explosion allows for the fusion of heavier elements.

Question 4

The Type II supernova that created the Crab Nebula was seen by Chinese and Arab astronomers in the year A.D.1054.Because the star is 6,500 light-years away from us,we know the star exploded in the year

Accepted Answer

The supernova was observed in A.D. 1054, and since the star is 6,500 light-years away, the explosion actually occurred 6,500 years before it was seen on Earth, which is 5446 B.C.

Question 5

What characteristic of a star cluster is used to determine its age?

Accepted Answer

The color of the main sequence turnoff in the cluster is used to determine its age. This is because the turnoff point marks the end of hydrogen fusion in the cluster's most massive stars, and the age of the cluster can be estimated from the time it took for these stars to exhaust their fuel.

Question 6

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

Accepted Answer

Most of the energy produced in the core of a high-mass star during heavy element fusion is carried away by neutrinos, which escape the star without interacting much with its matter, thus not contributing significantly to the star's luminosity.

Question 7

Which of the following is NOT a common characteristic of a neutron star?

Accepted Answer

All of these characteristics (extremely high density, enormous magnetic field, and very short rotation period) are common to neutron stars.

Question 8

An iron core cannot support a massive main-sequence star because

Accepted Answer

Iron cannot fuse with other nuclei to produce energy. This means that there is no energy source to counterbalance the force of gravity, causing the star to collapse under its own weight. This results in a supernova explosion, which can leave behind a neutron star or black hole.

Question 9

If a  main-sequence star loses mass at a rate of  then how much mass will it lose in its 3-million-year lifetime?

Accepted Answer

The answer of If a  main-sequence star loses mass...

Question 10

If you measure the average brightness and pulsation period of a Cepheid variable star,you can also determine its

Accepted Answer

By measuring the period and brightness of a Cepheid variable star, you can use the period-luminosity relationship to determine the star's distance from Earth. This relationship is based on the fact that there is a correlation between the period (how quickly the star pulsates) and the luminosity (brightness) of the star. Therefore, the best choice in this case is C, distance. Age, rotation period, and mass cannot be determined solely from the period and brightness measurements of a Cepheid variable star.

Question 11

The main difference between Cepheid variable stars and RR Lyrae stars is

Accepted Answer

Cepheid variable stars are generally more massive than RR Lyrae stars. Both types of stars are pulsating variables, but their mass and evolutionary stages differ significantly.

Question 12

During the main-sequence evolution of a massive star,increasingly heavier elements are fused in the core,giving the core support for

Accepted Answer

As a massive star evolves, each successive stage of fusion (involving heavier elements) provides energy for a shorter duration because the fusion of heavier elements is less efficient and consumes fuel more rapidly.

Question 13

Neutron stars have masses that range from

Accepted Answer

The answer of Neutron stars have masses that range from
...

Question 14

Once silicon burning begins to fuse iron in the core of a high-mass main-sequence star,it only has a few __________ left to live.

Accepted Answer

Once silicon burning begins in a high-mass star, it only has a few days left to live because iron fusion does not release energy, leading to a rapid collapse and supernova.

Question 15

What is the minimum mass main-sequence star that becomes a Type II supernova?

Accepted Answer

The answer of What is the minimum mass main-sequence star...

Question 16

The collapse of the core of a high-mass star at the end of its life lasts approximately

Accepted Answer

The collapse of the core of a high-mass star at the end of its life, also known as a supernova, lasts approximately one second. During this brief moment, the core collapses inward under its own gravity, causing an explosion that ejects the outer layers of the star.

Question 17

A neutron star contains a mass of up to  in a sphere with a diameter approximately the size of

Accepted Answer

The answer of A neutron star contains a mass of...

Question 18

We can identify only a small fraction of all the pulsars that exist in our galaxy because

Accepted Answer

Pulsars emit synchrotron radiation in a beam, much like a lighthouse. If the beam is not pointed in our direction, we cannot detect it. Therefore, only a small fraction of pulsars are visible from Earth.

Question 19

Suppose you measured H-R diagrams for the two star clusters pictured below.Which of the following statements is TRUE?

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The answer of Suppose you measured H-R diagrams for the...

Question 20

You observed three different star clusters and found that the main-sequence turnoff stars in Cluster 1 had spectral type A,the main-sequence turnoff stars in Cluster 2 had spectral type B,and the main-sequence turnoff stars in Cluster 3 had spectral type G.Which star cluster is the youngest?

Accepted Answer

The answer of You observed three different star clusters and...

Quiz 17: Live Fast,die Younghigh-Mass Stellar Evolution