Question 1

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 2

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 3

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 4

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 5

If an 8M⨀ star loses mass at an average rate of 10−6 M⨀/yr in a stellar wind,how many years would it take for its mass be reduced to 6M⨀? Would this amount of mass loss be possible in the star's lifetime?

Accepted Answer

If R is the mass loss rate and M is the

Question 6

An 8M⨀ star will eventually die as a Type I supernova.

Accepted Answer

A) True 
 B)False

Question 7

During the main-sequence evolution of a massive star,increasingly heavier elements are fused in the core,giving the core support for:

Accepted Answer

A) longer and longer times 
B) shorter and shorter times 
C) an approximately equal amount of time 
D) approximately 10,000 years 
E) only a few days 
A) longer and longer times 
B) shorter and shorter times 
C) an approximately equal amount of time 
D) approximately 10,000 years 
E) only a few days

Question 8

How do Cepheid variable stars differ from RR Lyrae variable stars in their masses,luminosities,and periods?

Accepted Answer

Cepheids are supergiant,massive stars,wh

Question 9

You observe a distant galaxy,and see that most of the blue light is coming from regions along spiral arms and in the outer regions of the galaxy.This blue light indicates that these regions contain:

Accepted Answer

A) likely sites for planets with life 
B) neutron stars and white dwarf stars 
C) K-type supergiants 
D) only old,low-mass stars 
E) young,massive stars 
A) likely sites for planets with life 
B) neutron stars and white dwarf stars 
C) K-type supergiants 
D) only old,low-mass stars 
E) young,massive stars

Question 10

Explain the effect of core convection on the main-sequence lifetime of massive main-sequence stars and contrast this to the situation in low-mass stars.

Accepted Answer

In massive stars,convection mixes the he

Question 11

One reason why we think neutron stars were formed in supernova explosions is that:

Accepted Answer

A) all supernova remnants contain pulsars 
B) pulsars are made of heavy elements,such as those produced in supernova explosions 
C) pulsars are often found near Cepheids and Wolf-Rayet stars,which are also signs of massive star formation 
D) pulsars spin very rapidly,as did the massive star just before it exploded 
E) pulsars sometimes have material around them that looks like the ejecta from supernovae 
A) all supernova remnants contain pulsars 
B) pulsars are made of heavy elements,such as those produced in supernova explosions 
C) pulsars are often found near Cepheids and Wolf-Rayet stars,which are also signs of massive star formation 
D) pulsars spin very rapidly,as did the massive star just before it exploded 
E) pulsars sometimes have material around them that looks like the ejecta from supernovae

Question 12

You observed three different star clusters and found that the main-sequence turnoff stars in Cluster 1 had spectral type F,the main-sequence turnoff stars in Cluster 2 had spectral type A,and the main-sequence turnoff stars in Cluster 3 had spectral type G.Which star cluster is the youngest and which one is the oldest?

Accepted Answer

A) Cluster 1 is the youngest and cluster 2 is the oldest. 
B) Cluster 2 is the youngest and cluster 1 is the oldest. 
C) Cluster 2 is the youngest and cluster 3 is the oldest. 
D) Cluster 3 is the youngest and cluster 1 is the oldest. 
E) Cluster 3 is the youngest and cluster 2 is the oldest. 
A) Cluster 1 is the youngest and cluster 2 is the oldest. 
B) Cluster 2 is the youngest and cluster 1 is the oldest. 
C) Cluster 2 is the youngest and cluster 3 is the oldest. 
D) Cluster 3 is the youngest and cluster 1 is the oldest. 
E) Cluster 3 is the youngest and cluster 2 is the oldest.

Question 13

A neutron star contains a mass of up to 3M⨀ in a sphere with a diameter approximately the size of:

Accepted Answer

A) an atomic nucleus 
B) an apple 
C) a school bus 
D) a city 
E) the Earth 
A) an atomic nucleus 
B) an apple 
C) a school bus 
D) a city 
E) the Earth

Question 14

Pulsating variable stars are more commonly known as pulsars.

Accepted Answer

A) True 
 B)False

Question 15

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

Accepted Answer

A) True 
 B)False

Question 16

Which of the following is NOT a common characteristic of a neutron star?

Accepted Answer

A) extremely high density 
B) enormous magnetic field 
C) very short rotation period 
D) large radius 
E) source of pulsars 
A) extremely high density 
B) enormous magnetic field 
C) very short rotation period 
D) large radius 
E) source of pulsars

Question 17

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 18

If you measure the average brightness and pulsation period of a Cepheid variable star,you can also determine its:

Accepted Answer

A) age 
B) rotation period 
C) distance 
D) mass 
E) composition 
A) age 
B) rotation period 
C) distance 
D) mass 
E) composition

Question 19

The nuclear reaction that releases the most energy per kilogram is:

Accepted Answer

A) silicon fusing to iron 
B) oxygen fusing to silicon 
C) carbon fusing to magnesium 
D) helium fusing to carbon 
E) hydrogen fusing to helium 
A) silicon fusing to iron 
B) oxygen fusing to silicon 
C) carbon fusing to magnesium 
D) helium fusing to carbon 
E) hydrogen fusing to helium

Question 20

Why do free neutrons released in supernova reactions so easily create new heavy elements?

Accepted Answer

Neutrons have no electric charge,so ther

Exam 17: Evolution of High-Mass Stars

The luminosity of a Cepheid star varies in time because:

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

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

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

If an 8M⨀ star loses mass at an average rate of 10−6 M⨀/yr in a stellar wind,how many years would it take for its mass be reduced to 6M⨀? Would this amount of mass loss be possible in the star's lifetime?

An 8M⨀ star will eventually die as a Type I supernova.

During the main-sequence evolution of a massive star,increasingly heavier elements are fused in the core,giving the core support for:

How do Cepheid variable stars differ from RR Lyrae variable stars in their masses,luminosities,and periods?

You observe a distant galaxy,and see that most of the blue light is coming from regions along spiral arms and in the outer regions of the galaxy.This blue light indicates that these regions contain:

Explain the effect of core convection on the main-sequence lifetime of massive main-sequence stars and contrast this to the situation in low-mass stars.

One reason why we think neutron stars were formed in supernova explosions is that:

A neutron star contains a mass of up to 3M⨀ in a sphere with a diameter approximately the size of:

Pulsating variable stars are more commonly known as pulsars.

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

Which of the following is NOT a common characteristic of a neutron star?

What causes massive stars to expel their outer layers?

If you measure the average brightness and pulsation period of a Cepheid variable star,you can also determine its:

The nuclear reaction that releases the most energy per kilogram is:

Why do free neutrons released in supernova reactions so easily create new heavy elements?

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 Adornments Moons 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

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If an 8M_⨀ star loses mass at an average rate of 10⁻⁶ M_⨀/yr in a stellar wind,how many years would it take for its mass be reduced to 6M_⨀? Would this amount of mass loss be possible in the star's lifetime?

An 8M_⨀ star will eventually die as a Type I supernova.

A neutron star contains a mass of up to 3M_⨀ in a sphere with a diameter approximately the size of: