Question 1

What is a T Tauri star?

Accepted Answer

A)  young G, K, or M star that is ejecting gas 
B)  giant or supergiant star that varies regularly in brightness 
C)  giant or supergiant star that varies randomly in brightness 
D)  massing O or B star that ionizes hydrogen in interstellar space 
A)  young G, K, or M star that is ejecting gas 
B)  giant or supergiant star that varies regularly in brightness 
C)  giant or supergiant star that varies randomly in brightness 
D)  massing O or B star that ionizes hydrogen in interstellar space

Question 2

The "zero-age main sequence" describes the sequence of stars in the Hertzsprung-Russell diagram that

Accepted Answer

A)  contain no processed elements (elements heavier than hydrogen or helium). 
B)  are just beginning to convert helium into carbon in their cores. 
C)  have just collapsed from the interstellar medium. 
D)  have just become stable objects. 
A)  contain no processed elements (elements heavier than hydrogen or helium). 
B)  are just beginning to convert helium into carbon in their cores. 
C)  have just collapsed from the interstellar medium. 
D)  have just become stable objects.

Question 3

Because all the stars in a cluster begin forming at the same time, the stars arrive on the main sequence at

Accepted Answer

A)  the same time. 
B)  different times; more massive stars arrive first. 
C)  different times; less massive stars arrive first. 
D)  different times; later spectral types (G, K, M) arrive first. 
A)  the same time. 
B)  different times; more massive stars arrive first. 
C)  different times; less massive stars arrive first. 
D)  different times; later spectral types (G, K, M) arrive first.

Question 4

Most of the energy emitted by a protostar comes from

Accepted Answer

A)  radioactive elements. 
B)  gravitational potential energy being converted to heat as the protostar collapses. 
C)  infalling material colliding with the protostar's surface. 
D)  nuclear fusion. 
A)  radioactive elements. 
B)  gravitational potential energy being converted to heat as the protostar collapses. 
C)  infalling material colliding with the protostar's surface. 
D)  nuclear fusion.

Question 5

Stars are formed from interstellar matter. Why then are stars in open clusters metal-rich, while stars in globular clusters are metal-poor?

Accepted Answer

A)  Open clusters contain very hot stars that produce metals by nuclear reactions in their outer layers. 
B)  Globular clusters have "burned" their heavy elements over their longer lifetime. 
C)  Globular clusters are too young for their stars to have produced any significant amount of metals. 
D)  Open clusters are young, and stars have formed from material that has been enriched in metals by supernova explosions of previous stars. 
A)  Open clusters contain very hot stars that produce metals by nuclear reactions in their outer layers. 
B)  Globular clusters have "burned" their heavy elements over their longer lifetime. 
C)  Globular clusters are too young for their stars to have produced any significant amount of metals. 
D)  Open clusters are young, and stars have formed from material that has been enriched in metals by supernova explosions of previous stars.

Question 6

The age of a cluster can be determined by

Accepted Answer

A)  carrying out a number count of the stars in the cluster. 
B)  measuring the cluster's speed of motion relative to the Sun. 
C)  determining the turnoff point on the main sequence of the cluster's Hertzsprung-Russell diagram. 
D)  observing the cluster's position in the sky with respect to the Sun. 
A)  carrying out a number count of the stars in the cluster. 
B)  measuring the cluster's speed of motion relative to the Sun. 
C)  determining the turnoff point on the main sequence of the cluster's Hertzsprung-Russell diagram. 
D)  observing the cluster's position in the sky with respect to the Sun.

Question 7

Of all the low-mass red dwarfs (0.08 M < M < 0.4 M) that have formed since the Galaxy came into being 15 billion years ago, how many are presently on the main sequence?

Accepted Answer

A)  none 
B)  a few, less than 20% 
C)  most of them, more than 80% 
D)  all 
A)  none 
B)  a few, less than 20% 
C)  most of them, more than 80% 
D)  all

Question 8

The energy required to ionize the hydrogen gas in an emission nebula (H II region) comes from

Accepted Answer

A)  UV emission from hot O and B stars. 
B)  supernovae (exploding stars). 
C)  collisions between gas clouds in interstellar space. 
D)  T Tauri stars. 
A)  UV emission from hot O and B stars. 
B)  supernovae (exploding stars). 
C)  collisions between gas clouds in interstellar space. 
D)  T Tauri stars.

Question 9

Which factor, more than any other, modifies the evolutionary tracks of stars in binary combinations compared with their single-star counterparts?

Accepted Answer

A)  tidal distortion of the shapes of the stars 
B)  reduction of the quantum mechanical limitation on continued shrinking of one star by the gravitational field of the second star 
C)  mass exchange between the stars 
D)  radiation from one star heating the surface of the second star 
A)  tidal distortion of the shapes of the stars 
B)  reduction of the quantum mechanical limitation on continued shrinking of one star by the gravitational field of the second star 
C)  mass exchange between the stars 
D)  radiation from one star heating the surface of the second star

Question 10

What fraction of the mass of a typical interstellar cloud is helium?

Accepted Answer

A)  50 percent 
B)  2 percent 
C)  10 percent 
D)  25 percent 
A)  50 percent 
B)  2 percent 
C)  10 percent 
D)  25 percent

Question 11

The energy emitted by a star increases as the fourth power of its surface temperature, and a red giant star has a lower temperature than the Sun. Why then is the luminosity of a red giant about 1000 times greater than that of the Sun?

Accepted Answer

A)  A red giant is bigger and therefore has a much larger surface area. 
B)  The energy transfer from a red giant's interior is much more efficient than the transfer is in the Sun. 
C)  More of a red giant's total output of energy is in the visible range than is the energy of the Sun, and hence the red giant appears brighter. 
D)  A red giant's nuclear furnace produces much more energy than does that of the Sun. 
A)  A red giant is bigger and therefore has a much larger surface area. 
B)  The energy transfer from a red giant's interior is much more efficient than the transfer is in the Sun. 
C)  More of a red giant's total output of energy is in the visible range than is the energy of the Sun, and hence the red giant appears brighter. 
D)  A red giant's nuclear furnace produces much more energy than does that of the Sun.

Question 12

A star cluster at a great distance from the Sun, but inside the Milky Way, appears to be fainter than a similar star cluster at a closer distance. Part of this is the expected result from the inverse square law, but the distant cluster will also appear fainter than expected by distance alone because

Accepted Answer

A)  the photons of light become "tired" and appear less bright as they travel. 
B)  the cosmological redshift has moved some of the light into the infrared spectral region. 
C)  star clusters are systematically smaller and hence less bright the farther they are from the galactic center and hence from the Sun. 
D)  light is scattered and absorbed by interstellar dust and gas between distant clusters and Earth. 
A)  the photons of light become "tired" and appear less bright as they travel. 
B)  the cosmological redshift has moved some of the light into the infrared spectral region. 
C)  star clusters are systematically smaller and hence less bright the farther they are from the galactic center and hence from the Sun. 
D)  light is scattered and absorbed by interstellar dust and gas between distant clusters and Earth.

Question 13

A star is observed to be on or close to the main-sequence region of the Hertzsprung-Russell diagram. What particular feature of stellar behavior can be inferred by this observation?

Accepted Answer

A)  The star is generating internal energy by hydrogen fusion. 
B)  The star is generating energy by helium fusion, having stopped hydrogen "burning." 
C)  The star is slowly shrinking and thereby releasing gravitational potential energy as it slides down the main sequence from top left to bottom right across the H-R diagram. 
D)  Stars that have reached the main sequence have ceased nuclear "burning" and are simply cooling down by emitting radiation. 
A)  The star is generating internal energy by hydrogen fusion. 
B)  The star is generating energy by helium fusion, having stopped hydrogen "burning." 
C)  The star is slowly shrinking and thereby releasing gravitational potential energy as it slides down the main sequence from top left to bottom right across the H-R diagram. 
D)  Stars that have reached the main sequence have ceased nuclear "burning" and are simply cooling down by emitting radiation.

Question 14

Cepheid variables pulsate because they contain a layer that alternately blocks photons while heating and then becomes transparent to photons as it expands. What substance composes this layer?

Accepted Answer

A)  hydrogen 
B)  deuterium 
C)  ionized helium 
D)  twice ionized carbon 
A)  hydrogen 
B)  deuterium 
C)  ionized helium 
D)  twice ionized carbon

Question 15

A T Tauri star is at what stage of its stellar evolution?

Accepted Answer

A)  just before red giant phase, when variability begins 
B)  well-established on the main sequence 
C)  the end of its life, decaying away and cooling 
D)  pre-main-sequence phase 
A)  just before red giant phase, when variability begins 
B)  well-established on the main sequence 
C)  the end of its life, decaying away and cooling 
D)  pre-main-sequence phase

Question 16

In which part of the electromagnetic spectrum are molecules in the interstellar medium MOST easily detected?

Accepted Answer

A)  visible light 
B)  radio waves 
C)  X-rays 
D)  ultraviolet light 
A)  visible light 
B)  radio waves 
C)  X-rays 
D)  ultraviolet light

Question 17

In about 5 billion years the core of the Sun will be composed of

Accepted Answer

A)  hydrogen. 
B)  helium. 
C)  carbon. 
D)  silicon. 
A)  hydrogen. 
B)  helium. 
C)  carbon. 
D)  silicon.

Question 18

A Cepheid variable is a

Accepted Answer

A)  type of eclipsing binary star. 
B)  high-mass giant or supergiant star that pulsates regularly in size and brightness. 
C)  low-mass red giant that varies in size and brightness in an irregular way. 
D)  variable emission nebula near a T Tauri star. 
A)  type of eclipsing binary star. 
B)  high-mass giant or supergiant star that pulsates regularly in size and brightness. 
C)  low-mass red giant that varies in size and brightness in an irregular way. 
D)  variable emission nebula near a T Tauri star.

Question 19

Stars in a binary system are useful in studying mass transfers because the two stars have the same

Accepted Answer

A)  mass. 
B)  age. 
C)  spectral type. 
D)  radius. 
A)  mass. 
B)  age. 
C)  spectral type. 
D)  radius.

Question 20

Objects with masses between 13 and 75 times the mass of Jupiter do not fuse hydrogen but do fuse deuterium and lithium into helium. What are such objects called?

Accepted Answer

A)  extrasolar planets 
B)  sub-brown dwarfs 
C)  brown dwarfs 
D)  red dwarfs 
A)  extrasolar planets 
B)  sub-brown dwarfs 
C)  brown dwarfs 
D)  red dwarfs

What is a T Tauri star?

The "zero-age main sequence" describes the sequence of stars in the Hertzsprung-Russell diagram that

Because all the stars in a cluster begin forming at the same time, the stars arrive on the main sequence at

Most of the energy emitted by a protostar comes from

Stars are formed from interstellar matter. Why then are stars in open clusters metal-rich, while stars in globular clusters are metal-poor?

The age of a cluster can be determined by

Of all the low-mass red dwarfs (0.08 M < M < 0.4 M) that have formed since the Galaxy came into being 15 billion years ago, how many are presently on the main sequence?

The energy required to ionize the hydrogen gas in an emission nebula (H II region) comes from

Which factor, more than any other, modifies the evolutionary tracks of stars in binary combinations compared with their single-star counterparts?

What fraction of the mass of a typical interstellar cloud is helium?

The energy emitted by a star increases as the fourth power of its surface temperature, and a red giant star has a lower temperature than the Sun. Why then is the luminosity of a red giant about 1000 times greater than that of the Sun?

A star cluster at a great distance from the Sun, but inside the Milky Way, appears to be fainter than a similar star cluster at a closer distance. Part of this is the expected result from the inverse square law, but the distant cluster will also appear fainter than expected by distance alone because

A star is observed to be on or close to the main-sequence region of the Hertzsprung-Russell diagram. What particular feature of stellar behavior can be inferred by this observation?

Cepheid variables pulsate because they contain a layer that alternately blocks photons while heating and then becomes transparent to photons as it expands. What substance composes this layer?

A T Tauri star is at what stage of its stellar evolution?

In which part of the electromagnetic spectrum are molecules in the interstellar medium MOST easily detected?

In about 5 billion years the core of the Sun will be composed of

A Cepheid variable is a

Stars in a binary system are useful in studying mass transfers because the two stars have the same

Objects with masses between 13 and 75 times the mass of Jupiter do not fuse hydrogen but do fuse deuterium and lithium into helium. What are such objects called?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 13: The Lives of Stars From Birth Through Middle Age

What is a T Tauri star?

The "zero-age main sequence" describes the sequence of stars in the Hertzsprung-Russell diagram that

Because all the stars in a cluster begin forming at the same time, the stars arrive on the main sequence at

Most of the energy emitted by a protostar comes from

Stars are formed from interstellar matter. Why then are stars in open clusters metal-rich, while stars in globular clusters are metal-poor?

The age of a cluster can be determined by

Of all the low-mass red dwarfs (0.08 M < M < 0.4 M) that have formed since the Galaxy came into being 15 billion years ago, how many are presently on the main sequence?

The energy required to ionize the hydrogen gas in an emission nebula (H II region) comes from

Which factor, more than any other, modifies the evolutionary tracks of stars in binary combinations compared with their single-star counterparts?

What fraction of the mass of a typical interstellar cloud is helium?

The energy emitted by a star increases as the fourth power of its surface temperature, and a red giant star has a lower temperature than the Sun. Why then is the luminosity of a red giant about 1000 times greater than that of the Sun?

A star is observed to be on or close to the main-sequence region of the Hertzsprung-Russell diagram. What particular feature of stellar behavior can be inferred by this observation?

Cepheid variables pulsate because they contain a layer that alternately blocks photons while heating and then becomes transparent to photons as it expands. What substance composes this layer?

A T Tauri star is at what stage of its stellar evolution?

In which part of the electromagnetic spectrum are molecules in the interstellar medium MOST easily detected?

In about 5 billion years the core of the Sun will be composed of

A Cepheid variable is a

Stars in a binary system are useful in studying mass transfers because the two stars have the same

Objects with masses between 13 and 75 times the mass of Jupiter do not fuse hydrogen but do fuse deuterium and lithium into helium. What are such objects called?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters