Question 1

What property of a star's spectral lines allows astronomers to measure stellar masses?

Accepted Answer

A)  redshift 
B)  width 
C)  variability 
D)  depth

Question 2

Which of the following must be measured in order to determine a star's proper motion?

Accepted Answer

A)  angular position at multiple times 
B)  mass 
C)  redshift or blueshift 
D)  radius

Question 3

Which of the following quantities is NOT necessary to observe in order to construct an HR diagram of a system of stars?

Accepted Answer

A)  distance to each star 
B)  mass of each star 
C)  color of each star 
D)  brightness of each star

Question 4

Which of the following is necessary to construct a modern model of a star?

Accepted Answer

A)  equations of hydrostatic equilibrium 
B)  computers 
C)  equations of energy transport 
D)  all of the above

Question 5

Why are stars considered to be thermodynamic systems?

Accepted Answer

A)  Stars are hot. 
B)  Stars are always in motion. 
C)  Stars are giant collections of atoms. 
D)  Stars are powered by combustion.

Question 6

What properties of Cepheid variable stars are most often measured to determine their distance?

Accepted Answer

A)  luminosity and brightness 
B)  period and brightness 
C)  luminosity and temperature 
D)  period and temperature

Question 7

What causes a star to leave the main sequence?

Accepted Answer

A)  the decreasing temperature of the star 
B)  the decreasing temperature of the star's core 
C)  the consumption of all the star's hydrogen 
D)  the consumption of the stellar core's hydrogen

Question 8

Which of the following quantities changes significantly during a star's main sequence lifetime?

Accepted Answer

A)  luminosity 
B)  mass 
C)  core composition 
D)  color

Question 9

In a typical observation of a globular cluster,90% of the observed stars will lie on the main sequence.What does this tell you about the life cycle of stars?

Accepted Answer

The answer of In a typical observation of a globular...

Question 10

What property of a star can best be used to determine its temperature?

Accepted Answer

A)  luminosity 
B)  color 
C)  brightness 
D)  velocity

Question 11

A star has a parallax of 0.05 arcseconds.How far away from Earth is the star?

Accepted Answer

A)  20 parsecs 
B)  5 parsecs 
C)  0.5 parsecs 
D)  0.05 parsecs

Question 12

On an HR diagram,the star Mira appears directly below the star Betelgeuse.Compared to Betelgeuse,Mira has a:

Accepted Answer

A)  lower surface temperature. 
B)  higher surface temperature. 
C)  larger radius. 
D)  smaller radius.

Question 13

Which of the following correctly orders the spectral types of stars from coolest to hottest?

Accepted Answer

A)  OMKGFBA 
B)  MKGFABO 
C)  ABFGKMO 
D)  OBAFGKM

Question 14

Stars A and B have equal brightness,but star B is eight times as far from Earth as star A.How much more luminous is star A than star B?

Accepted Answer

A)  1/64 
B)  1/8 
C)  8 
D)  64

Question 15

Which of the following stellar spectral types shows the most molecular absorption lines?

Accepted Answer

A)  O 
B)  A 
C)  M 
D)  G

Question 16

Which of the following environments would allow astronomers to produce an HR diagram that includes all phases of stellar evolution for stars with a wide range of masses?

Accepted Answer

A)  an open cluster of stars that formed less than 106 years ago 
B)  a globular cluster of stars that formed 1010 years ago 
C)  an open cluster of stars that formed 1010 years ago 
D)  a galactic center field with a mixture of ages

Question 17

What aspects of a star change significantly during its time on the main sequence?

Accepted Answer

The answer of What aspects of a star change significantly...

Question 18

A star 10 times more massive than the Sun fuses hydrogen to helium 3,000 times faster than the Sun.If the Sun spends 10 billion years on the main sequence,how long will the more massive star remain there?

Accepted Answer

A)  1011 years 
B)  109 years 
C)  3 × 107 years 
D)  3 × 106 years

Question 19

Massive stars:

Accepted Answer

A)  burn their fuel rapidly, so they have shorter lifetimes than low-mass stars. 
B)  have large fuel supplies, so they have longer lifetimes than low-mass stars. 
C)  use the efficient CNO cycle, so they have longer lifetimes than low-mass stars. 
D)  burn more elements, so they have longer lifetimes than low-mass stars.

Question 20

Star A is twice as luminous as star B but has half the temperature of star B.How large is the radius of star A compared to star B?

Accepted Answer

A)  23/2 as large 
B)  22 as large 
C)  25/2 as large 
D)  23 as large

Exam 11: Measuring the Stars: the Main Sequence and Its Meaning