Question 1

Which of the following is responsible for heating the bulk of the very hot intercloud gas?

Accepted Answer

A) high-energy radiation from stars 
B) supernovae 
C) young O and B stars 
D) planetary nebulae 
E) The heating is an even mix of all of the sources above. 
A) high-energy radiation from stars 
B) supernovae 
C) young O and B stars 
D) planetary nebulae 
E) The heating is an even mix of all of the sources above.

Question 2

Stars forming in molecular clouds tend to form first in the low-density periphery.

Accepted Answer

A) True 
 B)False

Question 3

Brown dwarfs are considered failed stars because:

Accepted Answer

A) they never reach masses larger than 50 Jupiter masses 
B) hydrogen fusion never begins in their cores 
C) convection never plays a role in their energy transport 
D) they primarily shine at infrared wavelengths 
E) they are never as luminous as the Sun 
A) they never reach masses larger than 50 Jupiter masses 
B) hydrogen fusion never begins in their cores 
C) convection never plays a role in their energy transport 
D) they primarily shine at infrared wavelengths 
E) they are never as luminous as the Sun

Question 4

Why do H II regions mark the regions where new stars are currently being formed?

Accepted Answer

H II regions contain ionized gas that is

Question 5

When looking at the space between stars,what might you see?

Accepted Answer

A) Nothing;it is empty. 
B) spacecraft 
C) gas 
D) dark matter 
E) none of the above 
A) Nothing;it is empty. 
B) spacecraft 
C) gas 
D) dark matter 
E) none of the above

Question 6

Why do stars form most often within molecular clouds?

Accepted Answer

Because that is wher

Question 7

In the densest molecular clouds,the average density is approximately 300 atoms/cm3.If a cube of molecular cloud gas with this density contained 100 M⨀ of material (the amount needed to make a 1 M⨀ star),what would be the length of a side of the cube in units of AU? For reference,the mass of the Sun is 2 × 1030 kg,the mass of a hydrogen atom is 1.7 × 10−27 kg,and 1 AU = 1.5 × 1011 m.

Accepted Answer

If the one side of the cube has length X

Question 8

What is the most likely explanation for the dark area in the image below?

Accepted Answer

A) It is a region where there are no stars. 
B) It is a region with lots of dark matter. 
C) It is a super-massive black hole. 
D) It is a region with thick dust blocking the starlight coming from behind. 
E) It is a dark star cluster. 
A) It is a region where there are no stars. 
B) It is a region with lots of dark matter. 
C) It is a super-massive black hole. 
D) It is a region with thick dust blocking the starlight coming from behind. 
E) It is a dark star cluster.

Question 9

An H II region signals the presence of:

Accepted Answer

A) newly formed stars 
B) young stars 
C) ionized hydrogen gas 
D) O- and B-type stars 
E) all of the above 
A) newly formed stars 
B) young stars 
C) ionized hydrogen gas 
D) O- and B-type stars 
E) all of the above

Question 10

Herbig-Haro objects are almost always found in pairs on either side of a young protostar.

Accepted Answer

A) True 
 B)False

Question 11

Dust in the ISM appears dark in _________ wavelengths and bright in _________ wavelengths.

Accepted Answer

A) visible;ultraviolet 
B) infrared;radio 
C) infrared;visible 
D) radio;ultraviolet 
E) visible;infrared 
A) visible;ultraviolet 
B) infrared;radio 
C) infrared;visible 
D) radio;ultraviolet 
E) visible;infrared

Question 12

When winds blow the gas away from a forming protostar it becomes visible as a T Tauri star.

Accepted Answer

A) True 
 B)False

Question 13

What is the energy source that powers brown dwarf stars?

Accepted Answer

Brown dwarfs shine because they are stil

Question 14

When a molecular cloud fragments and stars form,the least massive stars are the first to form while the most massive stars take longer to form.

Accepted Answer

A) True 
 B)False

Question 15

A protostar's evolutionary "track" in the H-R diagram traces out:

Accepted Answer

A) only how the protostar's radius changes with time 
B) how the protostar's luminosity,temperature,and radius change with time 
C) only how the protostar's luminosity changes with time 
D) only how the protostar's spectral type changes with time 
E) the protostar's location in the molecular cloud 
A) only how the protostar's radius changes with time 
B) how the protostar's luminosity,temperature,and radius change with time 
C) only how the protostar's luminosity changes with time 
D) only how the protostar's spectral type changes with time 
E) the protostar's location in the molecular cloud

Question 16

Describe the general process of how the interstellar medium can create a star.

Accepted Answer

Deep inside of a cold,molecular cloud,gr

Question 17

How are each of the following types of ISM detected by astronomers: hot intercloud gas,H II regions,neutral hydrogen gas,and molecular clouds.

Accepted Answer

The hot intercloud gas is detected by X-

Question 18

Below are three pictures of the disk of the Milky Way,taken in three different wavelength ranges.   Put the three pictures in order from shortest to longest wavelength.

Accepted Answer

A) I,II,III 
B) II,III,I 
C) I,III,II 
D) II,I,III 
E) III,I,II 
A) I,II,III 
B) II,III,I 
C) I,III,II 
D) II,I,III 
E) III,I,II

Question 19

Molecular clouds,which have temperatures of around 10 K,are best observed at _________ wavelengths.

Accepted Answer

A) X-ray 
B) ultraviolet 
C) optical 
D) infrared 
E) radio 
A) X-ray 
B) ultraviolet 
C) optical 
D) infrared 
E) radio

Question 20

Which of the following traits does NOT help slow or prevent the collapse of a gas cloud?

Accepted Answer

A) high mass 
B) high temperature 
C) turbulence 
D) magnetic fields 
E) angular momentum 
A) high mass 
B) high temperature 
C) turbulence 
D) magnetic fields 
E) angular momentum

Exam 15: Star Formation and the Interstellar Medium

Which of the following is responsible for heating the bulk of the very hot intercloud gas?

Stars forming in molecular clouds tend to form first in the low-density periphery.

Brown dwarfs are considered failed stars because:

Why do H II regions mark the regions where new stars are currently being formed?

When looking at the space between stars,what might you see?

Why do stars form most often within molecular clouds?

What is the most likely explanation for the dark area in the image below?

An H II region signals the presence of:

Herbig-Haro objects are almost always found in pairs on either side of a young protostar.

Dust in the ISM appears dark in _________ wavelengths and bright in _________ wavelengths.

When winds blow the gas away from a forming protostar it becomes visible as a T Tauri star.

What is the energy source that powers brown dwarf stars?

When a molecular cloud fragments and stars form,the least massive stars are the first to form while the most massive stars take longer to form.

A protostar's evolutionary "track" in the H-R diagram traces out:

Describe the general process of how the interstellar medium can create a star.

How are each of the following types of ISM detected by astronomers: hot intercloud gas,H II regions,neutral hydrogen gas,and molecular clouds.

Below are three pictures of the disk of the Milky Way,taken in three different wavelength ranges. Put the three pictures in order from shortest to longest wavelength.

Molecular clouds,which have temperatures of around 10 K,are best observed at _________ wavelengths.

Which of the following traits does NOT help slow or prevent the collapse of a gas cloud?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

Dust in the ISM appears dark in _ wavelengths and bright in _ wavelengths.