ASTR 1P01/02: Introduction to Astronomy I/II

Practice Exam #5

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

A black dwarf...

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

Question 2

What is interstellar extinction?

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

Question 3

In which stage of its life will a star with mass similar to the Sun have the largest diameter?

Main sequence.
White dwarf.
Red giant.

Question 4

What is left after a Type II supernova?

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

Question 5

Which kind of region is the most common?

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

Question 6

Consider a star with an initial mass of 15 solar masses. What will be this star's final state?

A brown dwarf.
A white dwarf.
A neutron star.

Question 7

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

Helium.
Hydrogen.
Iron.

Question 8

What are the most common particles in cosmic rays?

Electrons or positrons.
Helium nuclei.
Protons.

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 iron?

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

Question 10

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

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

Question 11

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

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

Question 12

Which of the following has the weakest magnetic field?

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

Question 13

Which is the least dense?

Interstellar dust
Earth's atmosphere
Interstellar gas

Question 14

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

Question 15

An emission nebula...

Creates its own light.
Blocks light.
Scatters light from nearby stars.

Question 16

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

5.9 GHz
1.4 GHz
21 GHz

Question 17

What prevents a neutron star from collapsing?

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

Question 18

If a star has more mass...

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

Question 19

Which is bigger?

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

Question 20

Can a white dwarf have 2.2 solar masses?

No.
Yes.
Depends on its radius.

Question 21

Compared to white dwarfs, neutron stars are...

Just as dense.
Less dense.
More dense.

Question 22

The triple-alpha process starts by fusing together two...

Beryllium nuclei.
Carbon nuclei.
Helium nuclei.

Question 23

A radiation-powered pulsar is currently 9 million years old. When it was 1 million years old, it rotated...

Faster.
At the same speed.
Slower.

Question 24

Which force tries to collapse every star throughout its life?

Gravity.
Pressure.
Electromagnetism.

Question 25

How long will a star with approximately 3.3 solar masses stay on the main sequence?

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