Question 1

If we look back to the first generation of stars made when the Galaxy was first forming, how do they differ from stars being formed today?

Accepted Answer

A)   the first generation stars never become red giants
B)   the first generation stars all live their lives much more slowly than stars today (so they last a long time) 
C)   the first generation stars cannot form planets of any kind
D)   the first generation stars contain little or no elements heavier than helium
E)   I disagree; I think first generation stars will be like stars forming today in all ways D

Question 2

Really massive stars differ from stars with masses like the Sun in that they

Accepted Answer

A)   go through all the stages of their lives more slowly
B)   do not really go through a main sequence stage in their lives
C)   can fuse elements beyond carbon and oxygen in their hot central regions
D)   are no longer forming in the Galaxy; they only formed very early in the Galaxy's history
E)   they are significantly less luminous after the main sequence stage is over C

Question 3

Why is it easier for red giants to lose mass than main sequence stars?

Accepted Answer

A)   red giants are much hotter on their surfaces, allowing gases to move away
B)   red giants are so big, the gravity at their surface (that holds material to the star)  is less
C)   red giants are made of carbon and oxygen throughout, which escape more easily
D)   all red giants explode at the end of their lives
E)   you can't fool me, stars lose the same amount of mass during every stage of their lives B

Question 4

Which of the following statements about the main sequence stage in the life of a star is FALSE?

Accepted Answer

A)   all stars spend the majority of their lives in the main sequence stage
B)   during the main sequence stage, energy to power the star is provided by the fusion of hydrogen
C)   main sequence stars are rare in the Galaxy, so we are lucky to be living around one
D)   different stars spend a different amounts of time (number of years)  in the main sequence stage, depending on the characteristics they were born with
E)   during the main sequence stage, the mass of any star does not change significantly

Question 5

In a science fiction television show set in the far future, a starship finds itself approaching a stellar association. What types of objects would they be most likely to notice in such an association as they approach?

Accepted Answer

A)   planets around most of the stars
B)   bright O and B type stars
C)   a very dense concentration of old stars right in the center of the association
D)   many remnants of stars that have finished their lives long ago
E)   the most noticeable thing would be the almost complete absence of any interstellar gas or dust in the area

Question 6

An astronomy student, for her PhD, really needs to estimate the age of a cluster of stars. Which of the following would be part of the process she would follow?

Accepted Answer

A)   measure the Doppler shift of a number of the stars in the cluster
B)   search for x-rays coming from the center of the cluster
C)   plot an H-R diagram for the stars in the cluster
D)   count the number of M type stars in the cluster
E)   search for planets like Jupiter around the stars in the center of the cluster

Question 7

Which of the following stages will our own Sun go through in the future:

Accepted Answer

A)   spending a long time on the main sequence
B)   expanding to become red giant
C)   eventually fusing helium into carbon
D)   giving off a planetary nebula
E)   all of the above

Question 8

Which of the following types of stars will spend the longest time (the greatest number of years) on the main sequence?

Accepted Answer

A)   O
B)   A
C)   G
D)   K
E)   you can't fool me; every star spends about the same number of years on the main sequence

Question 9

When the core of a star reaches a temperature of about 100 million degrees (K), something new happens in the core. What is this new event?

Accepted Answer

A)   hydrogen nuclei begin to fuse into heavy hydrogen (deuterium)  and then into helium
B)   two helium nuclei begin fusing of beryllium (element number 4) 
C)   the core explodes
D)   three helium nuclei begin fusing carbon (element number 6) 
E)   the fusion of iron (element 26)

Question 10

A group of graduate students, bored during a cloudy night at the observatory, begin to make bets about the time different stars will take to evolve. If they have a cluster of stars which were all born at roughly the same time, and want to know which star will become a red giant first, which of the following stars should they bet on?

Accepted Answer

A)   a star of about the same mass as our Sun
B)   a star that would type O on the main sequence star
C)   a star of about 1/2 the mass of our Sun
D)   a star of about 8% the mass of our Sun
E)   you can't fool me, all stars reach the red giant stage in roughly the same number of yearsSection 22.2: Star Clusters

Question 11

The oldest structures in our Galaxy turn out to be

Accepted Answer

A)   HII regions
B)   giant molecular clouds
C)   open clusters
D)   stellar associations
E)   globular clustersSection 22.4: The Further Evolution of Stars

Question 12

Why can a star with a mass like our Sun not fuse (produce) further elements beyond carbon and oxygen?

Accepted Answer

A)   because there are no elements heavier than those two; they are the heaviest nuclei in nature
B)   because they just cannot get hot enough for the fusion of heavier nuclei
C)   because all such stars explode before they can make any other elements
D)   because all such elements become radioactive and their nuclei break apart rather quickly
E)   because the cores of such stars get too hot for further types of fusion to be able to happen

Question 13

An eccentric Hollywood movie producer, vacationing in Australia, goes to an observatory and offers to make a big donation if they can show him a place in the Milky Way Galaxy where there are more than a million stars seen together. Which object would satisfy his extravagant tastes?

Accepted Answer

A)   The bright HII region NGC 3576
B)   The open star cluster NGC 6520
C)   The inner part of M42, the Orion Nebula, a star forming region
D)   The globular cluster Omega Centauri
E)   Alpha Centauri, the nearest star system to the Sun

Question 14

A type of star cluster that contains mostly very old stars is

Accepted Answer

A)   a globular star cluster
B)   a stellar association
C)   a galaxy
D)   an HII region
E)   an open cluster

Question 15

Which of the following statements about the mass of the Sun during its lifetime is correct?

Accepted Answer

A)   It will have the same exact mass from birth to death
B)   The only way the Sun loses mass is by turning a bit of mass into energy during fusion, and this loss is very small
C)   The Sun will lose some mass during the late periods of its life, but the amount loss will be less than 1 %.
D)   The Sun will lose a significant amount of mass during and after its red giant phase
E)   The Sun will lose almost ALL of its mass before it dies; the remaining mass will be less than the mass of Jupiter.Section 22.5: The Evolution of More Massive Stars

Question 16

How long a main sequence star remains on the main sequence in the H-R diagram depends most strongly on

Accepted Answer

A)   its initial composition
B)   the number of companion stars or planets orbiting it
C)   its radial velocity (as measured from the spectrum) 
D)   its mass
E)   its ability to fuse the element carbon into some other element

Question 17

On an H-R diagram of a cluster of stars, which characteristic of the diagram do astronomers use as a good indicator of the cluster's age?

Accepted Answer

A)   the number of M stars on the main sequence
B)   the lowest luminosity star that is visible in the cluster
C)   the point on the main sequence where stars begin to "turn off" -- to move toward the red giant region
D)   how high up on the main sequence M type stars are found
E)   the coolest surface temperature for a star that they can measure

Question 18

As a cluster of stars begins to age, which type of star in the cluster will move off the main sequence of the H-R diagram first?

Accepted Answer

A)   all the stars in a cluster are born at the same time; so they will all move off the main sequence at the same time, as they evolve
B)   G type stars, like our Sun
C)   M type stars, which are the coolest
D)   the lowest mass stars, which have the least amount of fuel for fusion
E)   the O and B type stars

Question 19

In a planetary nebula, the shell of expelled material is glowing intensely. What is the main source of energy for this glow?

Accepted Answer

A)   friction, as the atoms of the expelled shell rub against each other
B)   the explosion of the dying star
C)   ultraviolet radiation from the collapsing hot star at the center
D)   the fusion of hydrogen into helium in the nebula
E)   the change of electrons and protons into neutrons

Question 20

As a star becomes a giant, its outer layers are expanding. Where does the energy for expanding these layers come from?

Accepted Answer

A)   from the fusion of helium into carbon in the core
B)   from the long-term fusion of hydrogen into helium in the core
C)   from an explosion in the core
D)   from a magnetic dynamo effect in the star's outer layers, caused by a much stronger magnetic field inside the star
E)   from the fusion of hydrogen into helium in a shell around the core

Exam 22: Stars From Adolescence to Old Age