Question 1

What characteristic of a star cluster is used to determine its age?

Accepted Answer

A)  the chemical composition of stars in the cluster 
B)  the luminosity of the faintest stars in the cluster 
C)  the color of the main sequence turnoff in the cluster 
D)  the total number of stars in the cluster 
E)  the apparent diameter of the cluster 
A)  the chemical composition of stars in the cluster 
B)  the luminosity of the faintest stars in the cluster 
C)  the color of the main sequence turnoff in the cluster 
D)  the total number of stars in the cluster 
E)  the apparent diameter of the cluster

Question 2

Name three processes that speed the collapse of the core of a dying high-mass star.

Accepted Answer

(1) Photodisintegration uses up the ther

Question 3

Essentially all the elements heavier than iron in our Milky Way were formed:

Accepted Answer

A)  by supernovae 
B)  during the formation of black holes 
C)  by fusion in the cores of the most massive main-sequence stars 
D)  during the formation of planetary nebulae 
E)  during the initial stages of the Big Bang 
A)  by supernovae 
B)  during the formation of black holes 
C)  by fusion in the cores of the most massive main-sequence stars 
D)  during the formation of planetary nebulae 
E)  during the initial stages of the Big Bang

Question 4

Massive stars synthesize chemical elements going from helium up to iron:

Accepted Answer

A)  throughout the interior 
B)  primarily at the surface 
C)  only in the core of the star 
D)  along the equator of the star 
E)  in a deep convection zone in the interior of the star 
A)  throughout the interior 
B)  primarily at the surface 
C)  only in the core of the star 
D)  along the equator of the star 
E)  in a deep convection zone in the interior of the star

Question 5

Fusion reactions that create chemical elements heavier than oxygen require energy input; thus, these reactions cannot provide a star with power.

Accepted Answer

A) True 
 B)False

Question 6

Using the formula g = GMNS/R2NS, calculate the acceleration of gravity on a neutron star of mass 3 solar masses and radius 10 km, and express this in terms of the acceleration of gravity on the surface of the Earth (g = 9.8 m/s2).

Accepted Answer

A)  4 * 104 
B)  4*105 
C)  4 * 108 
D)  4 * 1011 
E)  4 * 1014 
A)  4 * 104 
B)  4*105 
C)  4 * 108 
D)  4 * 1011 
E)  4 * 1014

Question 7

If a 25M $\odot$ main-sequence star loses mass at a rate of 10 - 6 M $\odot$ /yr, then how much mass will it lose in its lifetime of 3 million years?

Accepted Answer

A)  3M $\odot$ 
B)  5M $\odot$ 
C)  8M $\odot$ 
D)  10M $\odot$ 
E)  12M $\odot$ 
A)  3M $\odot$ 
B)  5M $\odot$ 
C)  8M $\odot$ 
D)  10M $\odot$ 
E)  12M $\odot$

Question 8

What is one way that massive stars differ from low-mass stars?

Accepted Answer

A)  They are found at cooler temperatures on the main sequence. 
B)  They fuse carbon through silicon without leaving the main sequence. 
C)  Convection is important in their cores, which determines when the stars leave the main sequence. 
D)  They turn into red giants explosively. 
E)  Most of their fusion energy is emitted as neutrinos and not visible light. 
A)  They are found at cooler temperatures on the main sequence. 
B)  They fuse carbon through silicon without leaving the main sequence. 
C)  Convection is important in their cores, which determines when the stars leave the main sequence. 
D)  They turn into red giants explosively. 
E)  Most of their fusion energy is emitted as neutrinos and not visible light.

Question 9

We can determine the age of a star cluster by measuring the color of the reddest red giant stars in the cluster.

Accepted Answer

A) True 
 B)False

Question 10

What causes massive stars to expel their outer layers?

Accepted Answer

A)  radiation pressure 
B)  high magnetic fields 
C)  rapid rotation 
D)  carbon fusion 
E)  emission of neutrinos 
A)  radiation pressure 
B)  high magnetic fields 
C)  rapid rotation 
D)  carbon fusion 
E)  emission of neutrinos

Question 11

Which of these begins first in the core of a massive star?

Accepted Answer

A)  silicon fusion to iron 
B)  neon fusion to magnesium 
C)  carbon fusion to neon 
D)  helium fusion to carbon 
E)  hydrogen fusion to helium 
A)  silicon fusion to iron 
B)  neon fusion to magnesium 
C)  carbon fusion to neon 
D)  helium fusion to carbon 
E)  hydrogen fusion to helium

Question 12

The principal means by which high-mass stars generate energy on the main sequence is called:

Accepted Answer

A)  the proton-proton chain 
B)  the carbon-carbon reaction 
C)  the triple-alpha process 
D)  the CNO cycle 
E)  neutrino cooling 
A)  the proton-proton chain 
B)  the carbon-carbon reaction 
C)  the triple-alpha process 
D)  the CNO cycle 
E)  neutrino cooling

Question 13

Where did all heavy elements in the Sun come from?

Accepted Answer

A)  Previous generations of stars seeded the interstellar medium out of which the Sun formed. 
B)  Nearby supernova explosions directly contaminated the Sun's surface. 
C)  Nucleosynthesis within the Sun generated all the elements we see in the solar spectrum. 
D)  The Sun gobbled up some planets during the early days of our Solar System. 
E)  The solar wind carries away hydrogen and helium, leaving behind the heavy elements. 
A)  Previous generations of stars seeded the interstellar medium out of which the Sun formed. 
B)  Nearby supernova explosions directly contaminated the Sun's surface. 
C)  Nucleosynthesis within the Sun generated all the elements we see in the solar spectrum. 
D)  The Sun gobbled up some planets during the early days of our Solar System. 
E)  The solar wind carries away hydrogen and helium, leaving behind the heavy elements.

Question 14

The densest state of matter found in nature occurs inside a white dwarf star.

Accepted Answer

A) True 
 B)False

Question 15

The luminosity of a Cepheid star varies in time because:

Accepted Answer

A)  the entire star pulsates from its core to its surface 
B)  the outer envelope of the star pulsates in radius 
C)  the star rotates too quickly 
D)  the star is too massive to be stable 
E)  the star undergoes large surface temperature fluctuations 
A)  the entire star pulsates from its core to its surface 
B)  the outer envelope of the star pulsates in radius 
C)  the star rotates too quickly 
D)  the star is too massive to be stable 
E)  the star undergoes large surface temperature fluctuations

Question 16

Suppose the Milky Way makes 10 new stars per year and only 1 out of 5,000 will explode as a supernova. What would be the average time between supernova explosions in the Milky Way?

Accepted Answer

A)  50 years 
B)  500 years 
C)  5,000 years 
D)  50,000 years 
E)  500,000 years 
A)  50 years 
B)  500 years 
C)  5,000 years 
D)  50,000 years 
E)  500,000 years

Question 17

We can determine the age of a star cluster because stars of different masses go through their lives at different rates.

Accepted Answer

A) True 
 B)False

Question 18

Suppose you measured H-R diagrams for the two star clusters pictured below. Which cluster is older? Which cluster is farther away? Explain why.

Accepted Answer

The spectral type of Cluster A's main-se

Question 19

The main difference between Cepheid stars and RR Lyrae stars is:

Accepted Answer

A)  their masses 
B)  that Cepheids form at much greater distances from Earth 
C)  that RR Lyrae were discovered much earlier than Cepheids 
D)  their pulsation mechanisms 
E)  that Cepheids obey a period-luminosity relation, but RR Lyraes do not 
A)  their masses 
B)  that Cepheids form at much greater distances from Earth 
C)  that RR Lyrae were discovered much earlier than Cepheids 
D)  their pulsation mechanisms 
E)  that Cepheids obey a period-luminosity relation, but RR Lyraes do not

Question 20

Type I and Type II supernovae are approximately equal in luminosity.

Accepted Answer

A) True 
 B)False

Exam 17: Evolution of High-Mass Stars

What characteristic of a star cluster is used to determine its age?

Name three processes that speed the collapse of the core of a dying high-mass star.

Essentially all the elements heavier than iron in our Milky Way were formed:

Massive stars synthesize chemical elements going from helium up to iron:

Fusion reactions that create chemical elements heavier than oxygen require energy input; thus, these reactions cannot provide a star with power.

Using the formula g = GMNS/R2NS, calculate the acceleration of gravity on a neutron star of mass 3 solar masses and radius 10 km, and express this in terms of the acceleration of gravity on the surface of the Earth (g = 9.8 m/s2).

If a 25M ⊙\odot⊙ main-sequence star loses mass at a rate of 10 - 6 M ⊙\odot⊙ /yr, then how much mass will it lose in its lifetime of 3 million years?

What is one way that massive stars differ from low-mass stars?

We can determine the age of a star cluster by measuring the color of the reddest red giant stars in the cluster.

What causes massive stars to expel their outer layers?

Which of these begins first in the core of a massive star?

The principal means by which high-mass stars generate energy on the main sequence is called:

Where did all heavy elements in the Sun come from?

The densest state of matter found in nature occurs inside a white dwarf star.

The luminosity of a Cepheid star varies in time because:

Suppose the Milky Way makes 10 new stars per year and only 1 out of 5,000 will explode as a supernova. What would be the average time between supernova explosions in the Milky Way?

We can determine the age of a star cluster because stars of different masses go through their lives at different rates.

Suppose you measured H-R diagrams for the two star clusters pictured below. Which cluster is older? Which cluster is farther away? Explain why.

The main difference between Cepheid stars and RR Lyrae stars is:

Type I and Type II supernovae are approximately equal in luminosity.

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

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 Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

Using the formula g = GM_NS/R²_NS, calculate the acceleration of gravity on a neutron star of mass 3 solar masses and radius 10 km, and express this in terms of the acceleration of gravity on the surface of the Earth (g = 9.8 m/s²).

If a 25M _$\odot$ main-sequence star loses mass at a rate of 10 ^- ⁶ M _$\odot$ /yr, then how much mass will it lose in its lifetime of 3 million years?