Question 1

The youngest stars in the Orion Nebula and other star-forming regions also show

Accepted Answer

A)  circumstellar disks. 
B)  jets. 
C)  circumstellar disks and jets. 
A)  circumstellar disks. 
B)  jets. 
C)  circumstellar disks and jets.

Question 2

If a star's temperature increases in its interior, then more nuclear reactions will occur to push the star outward and its temperature will drop, causing the star to contract and eventually return to equilibrium.

Accepted Answer

A) True 
 B)False

Question 3

The hottest star in the Orion Nebula ____________hydrogen gas and makes it _____________.

Accepted Answer

A)  ionizes; glow 
B)  neutralizse; glow 
C)  ionizes; swallow the star 
A)  ionizes; glow 
B)  neutralizse; glow 
C)  ionizes; swallow the star

Question 4

________ are small dark nebulae about 1 light-year in diameter that contain 10 to 1,000 solar masses.

Accepted Answer

A)  HI regions 
B)  HII regions 
C)  Emission nebulae 
D)  Bok globules 
E)  Reflection nebulae 
A)  HI regions 
B)  HII regions 
C)  Emission nebulae 
D)  Bok globules 
E)  Reflection nebulae

Question 5

Why are interstellar absorption lines so narrow compared to the width of lines which originate in the photospheres of stars?

Accepted Answer

Much of the interstellar gas i

Question 6

The lower edge of the main-sequence band is known as ________ and represents the location in the H-R diagram at which stars begin their lives as main-sequence stars.

Accepted Answer

A)  the Coulomb barrier 
B)  hydrostatic equilibrium 
C)  the birth line 
D)  the zero-age main sequence 
E)  the evolutionary track 
A)  the Coulomb barrier 
B)  hydrostatic equilibrium 
C)  the birth line 
D)  the zero-age main sequence 
E)  the evolutionary track

Question 7

The thermal motions of the atoms in a gas cloud can make it collapse to form a protostar.

Accepted Answer

A) True 
 B)False

Question 8

HII regions are found near stars cooler than 25,000 K because large amounts of ultraviolet photons would totally destroy the hydrogen atoms in the gas.

Accepted Answer

A) True 
 B)False

Question 9

Main-sequence stars many times the mass of the Sun produce their energy by the set of nuclear reactions called the CNO cycle.

Accepted Answer

A) True 
 B)False

Question 10

If the dust around a protostar radiates most strongly at 30 microns or 30,000 nm, what is the approximate temperature of that dust? Hint: T in K = 3,000,000/wavelength in nm or use Wien's Law.

Accepted Answer

A)  100,000 K 
B)  10,000 K 
C)  1000 K 
D)  100 K 
E)  10 K 
A)  100,000 K 
B)  10,000 K 
C)  1000 K 
D)  100 K 
E)  10 K

Question 11

​
In the above visible + near infrared image, the white color is the ______, the red color is the __________, and the lack of white color (or black color) sandwiched between the upper white half-moon shape and the lower white half-moon shape is _________________.

Accepted Answer

A)  star, jet, the infrared part 
B)  disk, Herbig-Haro object, empty space 
C)  surface disk, jet, the dense dust disk 
D)  None of the other choices are correct. 
A)  star, jet, the infrared part 
B)  disk, Herbig-Haro object, empty space 
C)  surface disk, jet, the dense dust disk 
D)  None of the other choices are correct.

Question 12

T Tauri stars are believed to be young, high-mass main-sequence stars.

Accepted Answer

A) True 
 B)False

Question 13

The H-R diagram main-sequence of stars has a limit at the lower-mass or energy-output end because

Accepted Answer

A)  low-mass stars form from the interstellar medium very rarely. 
B)  low-mass objects are composed primarily of solids, not gases. 
C)  pressure does not depend on temperature in degenerate matter. 
D)  the lower limit represents when the radius of the star would be zero. 
E)  there is a minimum temperature for hydrogen nuclear fusion (the definition of a star). 
A)  low-mass stars form from the interstellar medium very rarely. 
B)  low-mass objects are composed primarily of solids, not gases. 
C)  pressure does not depend on temperature in degenerate matter. 
D)  the lower limit represents when the radius of the star would be zero. 
E)  there is a minimum temperature for hydrogen nuclear fusion (the definition of a star).

Question 14

The densest, coldest clouds are called _____________.

Accepted Answer

A)  reflection nebula 
B)  dark nebula 
C)  Bok globules 
D)  molecular clouds 
A)  reflection nebula 
B)  dark nebula 
C)  Bok globules 
D)  molecular clouds

Question 15

The above image is an example of interstellar reddening.

Accepted Answer

A) True 
 B)False

Question 16

The above image is a/an _________ wavelength image of a reflection nebula.

Accepted Answer

A)  infrared 
B)  visual 
C)  radio 
D)  X-ray 
A)  infrared 
B)  visual 
C)  radio 
D)  X-ray

Question 17

Why is there a lower end to the main sequence?

Accepted Answer

The mass-luminosity relation tells you w

Question 18

The condition of ____________________ means that the force due to gravity pushing down on a layer is exactly equal to the pressure pushing outward on that layer.

Accepted Answer

hydrostati

Question 19

A star has crossed the birth line and thus that star is now called a ________________.

Accepted Answer

A)  main-sequence star 
B)  protostar 
C)  YSO 
D)  ZAMS 
A)  main-sequence star 
B)  protostar 
C)  YSO 
D)  ZAMS

Question 20

Some massive stars only live a few million years.

Accepted Answer

A) True 
 B)False

The youngest stars in the Orion Nebula and other star-forming regions also show

If a star's temperature increases in its interior, then more nuclear reactions will occur to push the star outward and its temperature will drop, causing the star to contract and eventually return to equilibrium.

The hottest star in the Orion Nebula hydrogen gas and makes it _.

________ are small dark nebulae about 1 light-year in diameter that contain 10 to 1,000 solar masses.

Why are interstellar absorption lines so narrow compared to the width of lines which originate in the photospheres of stars?

The lower edge of the main-sequence band is known as ________ and represents the location in the H-R diagram at which stars begin their lives as main-sequence stars.

The thermal motions of the atoms in a gas cloud can make it collapse to form a protostar.

HII regions are found near stars cooler than 25,000 K because large amounts of ultraviolet photons would totally destroy the hydrogen atoms in the gas.

Main-sequence stars many times the mass of the Sun produce their energy by the set of nuclear reactions called the CNO cycle.

If the dust around a protostar radiates most strongly at 30 microns or 30,000 nm, what is the approximate temperature of that dust? Hint: T in K = 3,000,000/wavelength in nm or use Wien's Law.

In the above visible + near infrared image, the white color is the , the red color is the , and the lack of white color (or black color) sandwiched between the upper white half-moon shape and the lower white half-moon shape is _____________.

T Tauri stars are believed to be young, high-mass main-sequence stars.

The H-R diagram main-sequence of stars has a limit at the lower-mass or energy-output end because

The densest, coldest clouds are called _____________.

The above image is an example of interstellar reddening.

The above image is a/an _________ wavelength image of a reflection nebula.

Why is there a lower end to the main sequence?

The condition of ____________________ means that the force due to gravity pushing down on a layer is exactly equal to the pressure pushing outward on that layer.

A star has crossed the birth line and thus that star is now called a ________________.

Some massive stars only live a few million years.

Here and Now

A Users Guide to the Sky

Cycles of the Sun and Moon

The Origin of Modern Astronomy

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Deaths of Stars

Neutron Stars and Black Holes

The Milky Way Galaxy

Galaxies: Normal and Active

Modern Cosmology

Origin of the Solar System and Extrasolar Planets

Earth and Moon: Bases for Comparative Planetology

Mercury, Venus, and Mars

The Outer Solar System

Meteorites, Asteroids, and Comets

Astrobiology: Life on Other Worlds

Filters

Exam 9: The Formation and Structure of Stars

The youngest stars in the Orion Nebula and other star-forming regions also show

If a star's temperature increases in its interior, then more nuclear reactions will occur to push the star outward and its temperature will drop, causing the star to contract and eventually return to equilibrium.

The hottest star in the Orion Nebula ____________hydrogen gas and makes it _____________.

________ are small dark nebulae about 1 light-year in diameter that contain 10 to 1,000 solar masses.

Why are interstellar absorption lines so narrow compared to the width of lines which originate in the photospheres of stars?

The lower edge of the main-sequence band is known as ________ and represents the location in the H-R diagram at which stars begin their lives as main-sequence stars.

The thermal motions of the atoms in a gas cloud can make it collapse to form a protostar.

HII regions are found near stars cooler than 25,000 K because large amounts of ultraviolet photons would totally destroy the hydrogen atoms in the gas.

Main-sequence stars many times the mass of the Sun produce their energy by the set of nuclear reactions called the CNO cycle.

If the dust around a protostar radiates most strongly at 30 microns or 30,000 nm, what is the approximate temperature of that dust? Hint: T in K = 3,000,000/wavelength in nm or use Wien's Law.

​ In the above visible + near infrared image, the white color is the ______, the red color is the __________, and the lack of white color (or black color) sandwiched between the upper white half-moon shape and the lower white half-moon shape is _________________.

T Tauri stars are believed to be young, high-mass main-sequence stars.

The H-R diagram main-sequence of stars has a limit at the lower-mass or energy-output end because

The densest, coldest clouds are called _____________.

The above image is an example of interstellar reddening.

The above image is a/an _________ wavelength image of a reflection nebula.

Why is there a lower end to the main sequence?

The condition of ____________________ means that the force due to gravity pushing down on a layer is exactly equal to the pressure pushing outward on that layer.

A star has crossed the birth line and thus that star is now called a ________________.

Some massive stars only live a few million years.

Here and Now

A Users Guide to the Sky

Cycles of the Sun and Moon

The Origin of Modern Astronomy

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Deaths of Stars

Neutron Stars and Black Holes

The Milky Way Galaxy

Galaxies: Normal and Active

Modern Cosmology

Origin of the Solar System and Extrasolar Planets

Earth and Moon: Bases for Comparative Planetology

Mercury, Venus, and Mars

The Outer Solar System

Meteorites, Asteroids, and Comets

Astrobiology: Life on Other Worlds

Filters

The hottest star in the Orion Nebula hydrogen gas and makes it _.

In the above visible + near infrared image, the white color is the , the red color is the , and the lack of white color (or black color) sandwiched between the upper white half-moon shape and the lower white half-moon shape is _____________.