Question 1

The Hayashi track of a low-mass protostar in the H-R diagram is a path of approximately constant

Accepted Answer

A)  mass. 
B)  luminosity. 
C)  temperature. 
D)  radius. 
A)  mass. 
B)  luminosity. 
C)  temperature. 
D)  radius. C

Question 2

What is the energy source that powers brown dwarf stars?

Accepted Answer

Brown dwarfs shine because they are still radiating the energy produced in their gravitational collapse.Some of the most massive brown dwarf stars may shine briefly by burning deuterium or lithium,but that only provides a small amount of their energy for a brief period of time.

Question 3

Why do stars form most often within molecular clouds?

Accepted Answer

Because that is where the interstellar medium is both coldest and densest.

Question 4

Why does a protostar continue to collapse as it is forming?

Accepted Answer

It continually radiates away t

Question 5

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 6

At what wavelength are H II regions most clearly visible,and why do H II regions mark the regions where new stars are currently being formed?

Accepted Answer

H II regions are best seen at Halpha at

Question 7

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

Accepted Answer

A) True 
 B)False

Question 8

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

Accepted Answer

A) True 
 B)False

Question 9

We observe molecular hydrogen gas   using 21-cm emission.

Accepted Answer

A) True 
 B)False

Question 10

Why do some theories of star formation hypothesize that massive stars that form in a molecular cloud may influence the number and mass of the lower mass stars that form in the cloud?

Accepted Answer

Massive stars form quickly,on timescales

Question 11

Dust that is heated to 30 K will emit a blackbody spectrum that peaks at

Accepted Answer

A)  1 $\mu$m. 
B)  30 $\mu$m. 
C)  50 $\mu$m. 
D)  100 $\mu$m. 
A)  1 $\mu$m. 
B)  30 $\mu$m. 
C)  50 $\mu$m. 
D)  100 $\mu$m.

Question 12

The average density of the interstellar medium is

Accepted Answer

A)    . 
B)    . 
C)    . 
D)    . 
A)    . 
B)    . 
C)    . 
D)    .

Question 13

An accretion disk forms around a collapsing protostar because infalling material must conserve

Accepted Answer

A)  energy. 
B)  centrifugal force. 
C)  velocity. 
D)  angular momentum. 
A)  energy. 
B)  centrifugal force. 
C)  velocity. 
D)  angular momentum.

Question 14

When radiation from an object passes through the interstellar medium,

Accepted Answer

A)  the object appears dimmer. 
B)  the object appears bluer. 
C)  the object appears redder and dimmer. 
D)  the object's apparent velocity changes. 
A)  the object appears dimmer. 
B)  the object appears bluer. 
C)  the object appears redder and dimmer. 
D)  the object's apparent velocity changes.

Question 15

In the interstellar medium,molecules survive only in regions with

Accepted Answer

A)  low temperatures. 
B)  high densities. 
C)  lots of dust. 
D)  All of the above 
A)  low temperatures. 
B)  high densities. 
C)  lots of dust. 
D)  All of the above

Question 16

Which of the following stars spend the longest time on their Hayashi tracks?

Accepted Answer

A)    stars 
B)    stars 
C)    stars 
D)    stars 
A)    stars 
B)    stars 
C)    stars 
D)    stars

Question 17

Star formation is a quiet and tranquil process.

Accepted Answer

A) True 
 B)False

Question 18

"Weather" in the interstellar medium is produced

Accepted Answer

A)  only by supernovae. 
B)  by supernovae and strong winds from luminous stars. 
C)  by supernovae,strong winds from luminous stars,and fast-moving stars. 
D)  by supernovae,strong winds from luminous stars,fast-moving stars,and exploding planets. 
A)  only by supernovae. 
B)  by supernovae and strong winds from luminous stars. 
C)  by supernovae,strong winds from luminous stars,and fast-moving stars. 
D)  by supernovae,strong winds from luminous stars,fast-moving stars,and exploding planets.

Question 19

A protostar is usually in hydrostatic equilibrium during its collapse.

Accepted Answer

A) True 
 B)False

Question 20

How are Herbig-Haro objects related to T Tauri stars?

Accepted Answer

Herbig-Haro objects are ionized gas form

Exam 15: Star Formation and the Interstellar Medium

The Hayashi track of a low-mass protostar in the H-R diagram is a path of approximately constant

What is the energy source that powers brown dwarf stars?

Why do stars form most often within molecular clouds?

Why does a protostar continue to collapse as it is forming?

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

At what wavelength are H II regions most clearly visible,and why do H II regions mark the regions where new stars are currently being formed?

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

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

We observe molecular hydrogen gas using 21-cm emission.

Why do some theories of star formation hypothesize that massive stars that form in a molecular cloud may influence the number and mass of the lower mass stars that form in the cloud?

Dust that is heated to 30 K will emit a blackbody spectrum that peaks at

The average density of the interstellar medium is

An accretion disk forms around a collapsing protostar because infalling material must conserve

When radiation from an object passes through the interstellar medium,

In the interstellar medium,molecules survive only in regions with

Which of the following stars spend the longest time on their Hayashi tracks?

Star formation is a quiet and tranquil process.

"Weather" in the interstellar medium is produced

A protostar is usually in hydrostatic equilibrium during its collapse.

How are Herbig-Haro objects related to T Tauri stars?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Gravity and Orbitsa Celestial Ballet

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 Liquidthe Giant Planets

Gravity Is More Than Keplers Laws

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

A Run-Of-The-Mill G-Type Starour Sun

Stars in the Slow Lanelow-Mass Stellar Evolution

Live Fast,die Younghigh-Mass Stellar Evolution

Our Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

The Origin of Structure

Life

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