Practice Test

Please solve the following questions. This is not a real exam, it will not be graded, and you do not need to submit your solutions to anyone. The questions are simply intended to help you practice for the real exam.

These questions will not appear in the exam itself. Students who don't genuinely attempt to solve the questions on their own, and only memorize the solutions, will have a very hard time in the actual exam!

This sample exam is online, but the real exam will be given in person, at a time and place indicated on the course website.

THIS IS NOT THE ACTUAL EXAM!
THIS IS JUST A PRACTICE EXAM!
THE REAL EXAM IS IN PERSON!

If you need any clarifications for these questions, you can ask for them on the course Teams channel.

Question 1

In the process of star formation, after a core starts contracting but before hydrogen fusion begins, we have...

A protostar.
A main-sequence star.
A molecular cloud.

Question 2

Which of the following has the weakest magnetic field?

Planet Earth.
A normal (rotation- or accretion-powered) pulsar.
A magnetar.

Question 3

What are the most common particles in cosmic rays?

Helium nuclei.
Electrons or positrons.
Protons.

Question 4

What is interstellar extinction?

The process where stars become extinct due to losing their hydrogen supply.
The process where species of aliens become extinct.
The process where light from stars becomes dimmer.

Question 5

I saw a supernova in the sky. Where did it come from?

Material ejected from a high-mass star near death.
Material ejected from a low-mass star near death.
Material ejected from a planet near death.

Question 6

Which is bigger?

The Local Bubble.
The Local Fluff.
They are both the same size.

Question 7

What is a nova?

An explosion that occurs when a white dwarf accumulates matter from its binary companion and approaches the Chandrasekhar limit.
An explosion that occurs when a new star is created.
An explosion that occurs when a white dwarf accumulates matter from its binary companion but does not approach the Chandrasekhar limit.

Question 8

Compared to neutron stars, white dwarfs are...

Just as dense.
More dense.
Less dense.

Question 9

At the end of the life of a star with 20 solar masses, just before gravitational collapse, where would you expect to find hydrogen?

In a middle layer.
In the outermost layer.
In the core.

Question 10

Most of the mass of interstellar gas is in the form of...

Molecular clouds.
H II regions.
Hot gas.

Question 11

What is the frequency of light emitted in a spin-flip transition?

21 GHz
5.9 GHz
1.4 GHz

Question 12

The end products of the triple-alpha process are...

Beryllium nuclei.
Carbon nuclei.
Helium nuclei.

Question 13

Approximately how long will the Sun spend in the main sequence stage?

11 billion years.
1.3 billion years.
5 million years.

Question 14

What is left after a Type Ia supernova?

Nothing.
A white dwarf.
A neutron star or a black hole.

Question 15

Which kind of region is the most common?

Both regions are equally common.
H I.
H II.

Question 16

Can a white dwarf have 2.2 solar masses?

Yes.
Depends on its radius.
No.

Question 17

He I stands for...

Ionized hydrogen.
Neutral helium.
Ionized helium.

Question 18

Which force tries to expand every star throughout its life?

Pressure.
Gravity.
Electromagnetism.

Question 19

A rotation-powered pulsar is currently 3 million years old. When it will be 6 million years old, it will rotate...

Slower.
At the same speed.
Faster.

Question 20

How long will a star with approximately 0.8 solar masses stay on the main sequence?

Approximately 500 million years.
Approximately 14 billion years.
Approximately 10 million years.

Question 21

If a star has less mass...

Its lifetime is unaffected.
Its lifetime is longer.
Its lifetime is shorter.

Question 22

Which is the most dense?

Interstellar dust
Interstellar gas
Earth's atmosphere

Question 23

A white dwarf...

Produces bright light with energy from nuclear reactions.
Does not produce light anymore.
Produces faint light with stored heat energy.

Question 24

When a star is leaving the main sequence, its core is made primarily of...

Helium.
Iron.
Hydrogen.

Question 25

What prevents a white dwarf from collapsing?

Electron degeneracy pressure.
Pressure due to nuclear fusion.
Neutron degeneracy pressure and repulsion from the strong nuclear force.