Question 1

One star in a binary will almost always become a red giant before the other because

Accepted Answer

A)  one star is always larger in radius than the other. 
B)  binaries always have one star twice as massive as the other. 
C)  small differences in main-sequence masses yield large differences in main-sequence lifetimes. 
D)  the more massive binary star always gets more mass from the less massive binary star when both are main-sequence stars. 
E)  one star always spins faster than the other. 
A)  one star is always larger in radius than the other. 
B)  binaries always have one star twice as massive as the other. 
C)  small differences in main-sequence masses yield large differences in main-sequence lifetimes. 
D)  the more massive binary star always gets more mass from the less massive binary star when both are main-sequence stars. 
E)  one star always spins faster than the other.

Question 2

The Roche lobe of a star is the

Accepted Answer

A)  distance from the star where planets will be destroyed. 
B)  maximum distance between stars in a binary system. 
C)  limit to the star's radius before it is officially a red giant. 
D)  region around that star where its gravity is dominant. 
E)  maximum distance within which all planets will be tidally locked to the star. 
A)  distance from the star where planets will be destroyed. 
B)  maximum distance between stars in a binary system. 
C)  limit to the star's radius before it is officially a red giant. 
D)  region around that star where its gravity is dominant. 
E)  maximum distance within which all planets will be tidally locked to the star.

Question 3

Using the data in the figure shown below, identify the spectral type of a star that has a main-sequence lifetime of about 500 billion years.

Accepted Answer

A)  A5 
B)  F5 
C)  K0 
D)  G2 
E)  M5 
A)  A5 
B)  F5 
C)  K0 
D)  G2 
E)  M5

Question 4

As a white dwarf star gradually cools, its radius stays approximately constant.What is happening to the white dwarf's luminosity?

Accepted Answer

A)  It stays the same. 
B)  It increases. 
C)  It increases and then decreases periodically. 
D)  It decreases. 
E)  You can't tell from the information given. 
A)  It stays the same. 
B)  It increases. 
C)  It increases and then decreases periodically. 
D)  It decreases. 
E)  You can't tell from the information given.

Question 5

The luminosity of a star depends on

Accepted Answer

A)  its mass and age. 
B)  its mass. 
C)  its age. 
D)  its distance. 
E)  its mass, age, and distance. 
A)  its mass and age. 
B)  its mass. 
C)  its age. 
D)  its distance. 
E)  its mass, age, and distance.

Question 6

A nova is the result of which explosive situation?

Accepted Answer

A)  mass transfer onto a white dwarf 
B)  helium burning in a degenerate stellar core 
C)  a white dwarf that exceeds the Chandrasekhar limit 
D)  the collision of members of a binary system 
E)  runaway nuclear reactions in the core 
A)  mass transfer onto a white dwarf 
B)  helium burning in a degenerate stellar core 
C)  a white dwarf that exceeds the Chandrasekhar limit 
D)  the collision of members of a binary system 
E)  runaway nuclear reactions in the core

Question 7

What would you need to measure in a planetary nebula to determine how long ago its parent star died?

Accepted Answer

A)  the mass of the white dwarf 
B)  the mass and radius of the white dwarf 
C)  the nebula's temperature and radius 
D)  the nebula's radius and expansion velocity 
E)  the composition of the gas in the nebula 
A)  the mass of the white dwarf 
B)  the mass and radius of the white dwarf 
C)  the nebula's temperature and radius 
D)  the nebula's radius and expansion velocity 
E)  the composition of the gas in the nebula

Question 8

________ keeps the core of a red giant star from collapsing.

Accepted Answer

A)  Pressure from protons 
B)  Pressure from neutrons 
C)  Radiation pressure from hydrogen fusion 
D)  Degenerate pressure from electrons 
E)  Angular momentum 
A)  Pressure from protons 
B)  Pressure from neutrons 
C)  Radiation pressure from hydrogen fusion 
D)  Degenerate pressure from electrons 
E)  Angular momentum

Question 9

What is the escape velocity from the surface of a 1 MSUN AGB star that has a radius of 100 RSUN?

Accepted Answer

A)  60 km/s 
B)  120 km/s 
C)  240 km/s 
D)  620 km/s 
E)  800 km/s 
A)  60 km/s 
B)  120 km/s 
C)  240 km/s 
D)  620 km/s 
E)  800 km/s

Question 10

The Sun eventually will become a

Accepted Answer

A)  nova. 
B)  neutron star. 
C)  black hole. 
D)  white dwarf. 
E)  type M main-sequence star. 
A)  nova. 
B)  neutron star. 
C)  black hole. 
D)  white dwarf. 
E)  type M main-sequence star.

Question 11

Why is a star's time as a horizontal branch star so much shorter than its time as a main-sequence star?

Accepted Answer

The amount of helium available for fusio

Question 12

When a star depletes its core supply of hydrogen, the core will

Accepted Answer

A)  explode. 
B)  spin faster. 
C)  merge with the outer layers. 
D)  shrink. 
E)  immediately begin fusing helium into carbon. 
A)  explode. 
B)  spin faster. 
C)  merge with the outer layers. 
D)  shrink. 
E)  immediately begin fusing helium into carbon.

Question 13

When a spectral-type G2 star like the Sun leaves the main sequence, its

Accepted Answer

A)  luminosity and surface temperature both stay the same. 
B)  luminosity and surface temperature both decrease. 
C)  luminosity increases and its surface temperature decreases. 
D)  luminosity and surface temperature both increase. 
E)  luminosity decreases and its surface temperature increases. 
A)  luminosity and surface temperature both stay the same. 
B)  luminosity and surface temperature both decrease. 
C)  luminosity increases and its surface temperature decreases. 
D)  luminosity and surface temperature both increase. 
E)  luminosity decreases and its surface temperature increases.

Question 14

What is a planetary nebula?

Accepted Answer

A)  a planet surrounded by a glowing shell of gas 
B)  the disk of gas and dust surrounding a young star that will soon form a star system 
C)  the ejected envelope of a giant star surrounding the remnant of a star 
D)  a type of young, medium-mass star 
E)  leftover gas from a supernova explosion 
A)  a planet surrounded by a glowing shell of gas 
B)  the disk of gas and dust surrounding a young star that will soon form a star system 
C)  the ejected envelope of a giant star surrounding the remnant of a star 
D)  a type of young, medium-mass star 
E)  leftover gas from a supernova explosion

Question 15

If a main-sequence star's core temperature increased, fusion reaction rates would ________ because the protons would be moving ________.

Accepted Answer

A)  decrease; slower 
B)  increase; faster 
C)  increase; slower 
D)  remain unchanged; the same speed as before 
E)  decrease; faster 
A)  decrease; slower 
B)  increase; faster 
C)  increase; slower 
D)  remain unchanged; the same speed as before 
E)  decrease; faster

Question 16

Explain what the triple-alpha process is and when it takes place in evolving stars.

Accepted Answer

The triple-alpha process is the way that

Question 17

The largest low-mass stars have masses that are approximately

Accepted Answer

A)  1.5 MSUN. 
B)  1 MSUN. 
C)  3 MSUN. 
D)  5 MSUN. 
E)  10 MSUN. 
A)  1.5 MSUN. 
B)  1 MSUN. 
C)  3 MSUN. 
D)  5 MSUN. 
E)  10 MSUN.

Question 18

You observe a 0.8 MSUN white dwarf in a binary orbit around a main-sequence star of mass 1.4 MSUN.Which of the following is most likely the original mass of the star that became the white dwarf?

Accepted Answer

A)  0.5 MSUN 
B)  1 MSUN 
C)  0.8 MSUN 
D)  1.4 MSUN 
E)  3 MSUN 
A)  0.5 MSUN 
B)  1 MSUN 
C)  0.8 MSUN 
D)  1.4 MSUN 
E)  3 MSUN

Question 19

Calculate the main-sequence lifetimes of the following stars of different spectral types: B0 (18 MSUN), B5 (6 MSUN), A5 (2 MSUN), F5 (1.3 MSUN), and M0 (0.5 MSUN).What trend do you notice in your results?

Accepted Answer

Main-sequence lifetime: t_MS =

Question 20

When a star is stably fusing helium in its core, it is a ________ star.

Accepted Answer

A)  main-sequence 
B)  asymptotic giant branch 
C)  helium flash 
D)  horizontal branch 
E)  white dwarf 
A)  main-sequence 
B)  asymptotic giant branch 
C)  helium flash 
D)  horizontal branch 
E)  white dwarf

Exam 16: Evolution of Low-Mass Stars

One star in a binary will almost always become a red giant before the other because

The Roche lobe of a star is the

Using the data in the figure shown below, identify the spectral type of a star that has a main-sequence lifetime of about 500 billion years.

As a white dwarf star gradually cools, its radius stays approximately constant.What is happening to the white dwarf's luminosity?

The luminosity of a star depends on

A nova is the result of which explosive situation?

What would you need to measure in a planetary nebula to determine how long ago its parent star died?

________ keeps the core of a red giant star from collapsing.

What is the escape velocity from the surface of a 1 MSUN AGB star that has a radius of 100 RSUN?

The Sun eventually will become a

Why is a star's time as a horizontal branch star so much shorter than its time as a main-sequence star?

When a star depletes its core supply of hydrogen, the core will

When a spectral-type G2 star like the Sun leaves the main sequence, its

What is a planetary nebula?

If a main-sequence star's core temperature increased, fusion reaction rates would ________ because the protons would be moving ________.

Explain what the triple-alpha process is and when it takes place in evolving stars.

The largest low-mass stars have masses that are approximately

You observe a 0.8 MSUN white dwarf in a binary orbit around a main-sequence star of mass 1.4 MSUN.Which of the following is most likely the original mass of the star that became the white dwarf?

Calculate the main-sequence lifetimes of the following stars of different spectral types: B0 (18 MSUN), B5 (6 MSUN), A5 (2 MSUN), F5 (1.3 MSUN), and M0 (0.5 MSUN).What trend do you notice in your results?

When a star is stably fusing helium in its core, it is a ________ star.

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

What is the escape velocity from the surface of a 1 M_SUN AGB star that has a radius of 100 R_SUN?

If a main-sequence star's core temperature increased, fusion reaction rates would because the protons would be moving .

You observe a 0.8 M_SUNwhite dwarf in a binary orbit around a main-sequence star of mass 1.4 M_SUN.Which of the following is most likely the original mass of the star that became the white dwarf?

Calculate the main-sequence lifetimes of the following stars of different spectral types: B0 (18 M_SUN), B5 (6 M_SUN), A5 (2 M_SUN), F5 (1.3 M_SUN), and M0 (0.5 M_SUN).What trend do you notice in your results?