Copyright © 2010 Pearson Education, Inc. Clicker Questions Chapter 11 The Interstellar Medium

Copyright © 2010 Pearson Education, Inc.

Clicker Questions

Chapter 11The Interstellar

Medium


Question 1

Some regions of the Milky Way’s disk appear dark because

a) there are no stars there.

b) stars in that direction are obscured by interstellar gas.

c) stars in that direction are obscured by interstellar dust.

d) numerous black holes capture all the starlight behind them.


Question 1

Some regions of the Milky Way’s disk appear dark because

a) there are no stars there.

b) stars in that direction are obscured by interstellar gas.

c) stars in that direction are obscured by interstellar dust.

d) numerous black holes capture all the starlight behind them.

Dust grains are about the same size as visible light, and they can scatter or block the shorter wavelengths.


Question 2

When a star’svisible light passes through interstellar dust, the light we see

a) is dimmed and reddened.

b) appears to twinkle.

c) is Doppler shifted.

d) turns bluish in color.

e) ionizes the dust and creates emission lines.


Question 2

When a star’svisible light passes through interstellar dust, the light we see

a) is dimmed and reddened.

b) appears to twinkle.

c) is Doppler shifted.

d) turns bluish in color.

e) ionizes the dust and creates emission lines.

The same process results in wonderful sunsets, as

dust in the air scatters the Sun’s blue light, leaving

dimmer, redder light.


Question 3

Astronomers use the term nebula to refer to

a) outer envelopes of dying stars that drift gently into space.

b) remnants of stars that die by supernova.

c) clouds of gas and dust in interstellar space.

d) distant galaxies seen beyond our Milky Way.

e) All of the above are correct.


Question 3

Astronomers use the term nebula to refer to

a) outer envelopes of dying stars that drift gently into space.

b) remnants of stars that die by supernova.

c) clouds of gas and dust in interstellar space.

d) distant galaxies seen beyond our Milky Way.

e) All of the above are correct.

Nebula refers to any fuzzy patch – bright or

dark – in the sky.


Question 4

Interstellar gas is composed primarily of

a) 90% hydrogen, 9% helium, and 1% heavier elements.

b) molecules including water and CO2.

c) 50% hydrogen, 50% helium.

d) hydrogen, oxygen, and nitrogen.

e) 99% hydrogen, and 1% heavier elements.


Question 4

Interstellar gas is composed primarily of

a) 90% hydrogen, 9% helium, and 1% heavier elements.

b) molecules including water and CO2.

c) 50% hydrogen, 50% helium.

d) hydrogen, oxygen, and nitrogen.

e) 99% hydrogen, and 1% heavier elements.

The composition of interstellar gas mirrors that of the Sun, stars, and the

jovian planets.


Question 5a) gas and dust is moving away from Earth.

b) hydrogen gas is present.

c) dying stars have recently exploded.

d) cool red stars are hidden inside.

e) dust is present.

The reddish color of emission nebulae indicates that


Question 5a) gas and dust is moving away from Earth.

b) hydrogen gas is present.

c) dying stars have recently exploded.

d) cool red stars are hidden inside.

e) dust is present.

The reddish color of emission nebulae indicates that

Glowing hydrogen gas emits red light

around the Horsehead

nebula.


Question 6

21-centimeter radiation is important because

a) its radio waves pass unaffected through clouds of interstellar dust.

b) it arises from cool helium gas present throughout space.

c) it can be detected with optical telescopes.

d) it is produced by protostars.

e) it reveals the structure of new stars.


Question 6

21-centimeter radiation is important because

Cool atomic hydrogen gas produces 21-cm radio radiation

as its electron “flips” its direction of spin.

a) its radio waves pass unaffected through clouds of interstellar dust.

b) it arises from cool helium gas present throughout space.

c) it can be detected with optical telescopes.

d) it is produced by protostars.

e) it reveals the structure of new stars.


Question 7

Complex molecules in space are found

a) in the photospheres of red giant stars.

b) primarily inside dense dust clouds.

c) in the coronas of stars like our Sun.

d) scattered evenly throughout interstellar space.

e) surrounding energetic young stars.


Question 7

Complex molecules in space are found

a) in the photospheres of red giant stars.

b) primarily inside dense dust clouds.

c) in the coronas of stars like our Sun.

d) scattered evenly throughout interstellar space.

e) surrounding energetic young stars.

A radio telescope image of the outer portion of the Milky Way, revealing molecular cloud complexes.


Question 8

Stars are often born within groups known as

a) clans.

b) spiral waves.

c) aggregates.

d) clusters.

e) swarms.


Question 8

The Pleiades – a nearby open cluster – is a group of relatively

young stars about 400 light-years from the Sun.

Stars are often born within groups known as

a) clans.

b) spiral waves.

c) aggregates.

d) clusters.

e) swarms.


Question 9a) OB associations.

b) molecular cloud complexes.

c) aggregates.

d) globular clusters.

e) hives.Very young stars in small clusters of 10-100 members are known as


Question 9

Very young stars in small clusters of 10-100 members are known as

NGC 3603 is a newborn cluster of hot young blue Type O and B stars – a perfect OB association.

a) OB associations.

b) molecular cloud complexes.

c) aggregates.

d) globular clusters.

e) hives.


Question 10

All stars in a stellar cluster have roughly the same

a) temperature.

b) color.

c) distance.

d) mass.

e) luminosity.


Question 10

All stars in a stellar cluster have roughly the same

a) temperature.

b) color.

c) distance.

d) mass.

e) luminosity.

Stars in the Pleiades cluster vary in temperature, color, mass, and luminosity, but all lie about 440 light-years away.


Question 11

Globular clusters are typically observed

a) in the plane of our Galaxy.

b) above or below the plane of our Galaxy.

c) near to our Sun.

d) in the hearts of other galaxies.


Question 11

Globular clusters are typically observed

Globular clusters orbit the center of the Milky Way, and are usually seen above or below the galactic plane far from our Sun.

a) in the plane of our Galaxy.

b) above or below the plane of our Galaxy.

c) near to our Sun.

d) in the hearts of other galaxies.


Question 12

Stars in clusters & associations have about the same

a) age.

b) temperature.

c) mass.

d) color.

e) luminosity.


Question 12

Stars in clusters & associations have about the same

Most of the stars in a cluster form about the same time.

Stars in the Omega Centauri globular cluster are

estimated to be about 14 billion years old.

a) age.

b) temperature.

c) mass.

d) color.

e) luminosity.


Question 13

Objects more massive than our Sun form into stars

a) much slower, over billions of years.

b) in about the same time.

c) much faster, over tens of thousands of years.

d) not at all – they are unstable.


Question 13

Objects more massive than our Sun form into stars

a) much slower, over billions of years.

b) in about the same time.

c) much faster, over tens of thousands of years.

d) not at all – they are unstable.

More mass faster collapse

More mass faster start of fusion reactions

More mass a hotter, more luminous main sequence star


Question 14

How do single stars form within huge clouds of interstellar gas and dust?

a) Clouds fragment into smaller objects, forming many stars at one time.

b) One star forms; other matter goes into planets, moons, asteroids, & comets.

c) Clouds rotate & throw off mass until only enough is left to form one star.


Question 14

How do single stars form within huge clouds of interstellar gas and dust?

a) Clouds fragment into smaller objects, forming many stars at one time.

b) One star forms; other matter goes into planets, moons, asteroids, & comets.

c) Clouds rotate & throw off mass until only enough is left to form one star.

The theory of star formation predicts stars in a cluster would form about the same time.


Question 15

What is a T-Tauri star?

a) a collapsing cloud of gas about to become a protostar

b) a dying star

c) a cool main sequence star

d) a star releasing a planetary nebula

e) a protostar about to become a star


Question 15

What is a T-Tauri star?

a) a collapsing cloud of gas about to become a protostar

b) a dying star

c) a cool main sequence star

d) a star releasing a planetary nebula

e) a protostar about to become a star

T-Tauri stars often show jets of gas emitted in two directions —

“bipolar flow” — suggesting they are not yet stable.


Question 16

A key feature of globular clusters is that they have

a ) very few cool stars.

b) the oldest stars in our Galaxy.

c) lots of massive main sequence stars.

d) stars with very different ages.

e) high concentrations of metals.


Question 16

A key feature of globular clusters is that they have

a ) very few cool stars.

b) the oldest stars in our Galaxy.

c) lots of massive main sequence stars.

d) stars with very different ages.

e) high concentrations of metals.

The H–R diagram of a globular cluster has a low “turnoff point” indicating

its extreme age.

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Copyright © 2010 Pearson Education, Inc. Clicker Questions Chapter 11 The Interstellar Medium