Question 1

Stars A and B appear equally bright,but star A is twice as far away from us as star B.Which of the following is true?

Accepted Answer

A)   Star A is twice as luminous as star B.
B)   Star A is four times as luminous as star B.
C)   Star B is twice as luminous as star A.
D)   Star B is four times as luminous as star B. B

Question 2

All of the following are useful in determining the masses of stars in a binary system EXCEPT:

Accepted Answer

A)   the period of the orbits of the two stars.
B)   the average separation between the two stars.
C)   the luminosities of the two stars.
D)   the velocities of the two stars. C

Question 3

Describe the luminosity classes found on the H-R diagram below.

Accepted Answer

The luminosity classes on the H-R diagram include supergiants,bright giants,giants,and subgiants (I,II,III,IV),the main-sequence (V)stars,and the white dwarfs (WD).

Question 4

If given the image alone in the figure below,what further information might be required to determine that the stars are a visual binary system?

Accepted Answer

The answer of If given the image alone in the...

Question 5

Eclipsing binary systems:

Accepted Answer

A)   orbit in the plane of the sky.
B)   exhibit large radial velocity shifts.
C)   contain equal mass stars.
D)   contain stars that pass in front of one another during their orbit.

Question 6

What spectral class is the Sun?

Accepted Answer

A)   A0
B)   G2
C)   F5
D)   M3

Question 7

How is the distance to a star related to its parallax?

Accepted Answer

A)   Distance is directly proportional to parallax.
B)   Distance is inversely proportional to parallax.
C)   Distance is directly proportional to parallax squared.
D)   Distance is inversely proportional to parallax squared.

Question 8

In what ways are energy states of an atom like books occupying shelves in a bookcase?

Accepted Answer

The answer of In what ways are energy states of...

Question 9

Stars of similar temperatures but different sizes will have:

Accepted Answer

A)   similar luminosities but different masses.
B)   similar masses but different distances.
C)   different spectral types but similar luminosities.
D)   similar spectral types but different luminosities.

Question 10

What is the difference between brightness and luminosity?

Accepted Answer

A)   These are different names for the same property.
B)   Luminosity is how bright the star appears to us; brightness is how much light it emits.
C)   Brightness is how bright the star appears to us; luminosity is how much light it emits.
D)   Luminosity measures size; brightness measures temperature.

Question 11

You observe a binary star system and find that star 1 has a velocity of 20 m/s while star 2 has a velocity of 40 m/s.What is the ratio of masses of the two stars (M₁/M₂)? If star 2 has a mass of 2 solar masses what is the mass of star 1?

Accepted Answer

The answer of You observe a binary star system and...

Question 12

How are atoms excited,and why do they decay?

Accepted Answer

The answer of How are atoms excited,and why do they...

Question 13

In a binary star system that contains stars with 10 M¤ and 5 M¤,the velocity of the 10 M¤ star will be ________ times the velocity of the 5 M¤ star.

Accepted Answer

A)   0.2
B)   0.5
C)   1
D)   2

Question 14

How many arcseconds are there in a degree?

Accepted Answer

A)   60
B)   360
C)   3,600
D)   6,000

Question 15

The Hertzsprung-Russell (H-R)diagram (see figure below)is a graph of:

Accepted Answer

A)   mass versus brightness for stars.
B)   size versus mass for stars.
C)   luminosity versus surface temperature for stars.
D)   mass versus spectral type for stars.

Question 16

Roughly what percentage of stars are main-sequence stars?

Accepted Answer

A)   10 percent
B)   40 percent
C)   60 percent
D)   90 percent

Question 17

Why do O- and B-type stars have weaker hydrogen absorption lines than A-type stars?

Accepted Answer

A)   O- and B-type stars are cooler than A-type stars.
B)   A larger fraction of the surface hydrogen atoms in O- and B-type stars is ionized.
C)   O- and B-type stars have converted much more of their hydrogen into heavier elements.
D)   A-type stars have a higher mass than O- and B-type stars, and they have more hydrogen.

Question 18

Stars are made mostly of:

Accepted Answer

A)   helium.
B)   oxygen.
C)   hydrogen.
D)   nitrogen.

Question 19

Examine the figure below.On a typical H-R diagram,where are main-sequence stars that have the hottest surface temperatures located?

Accepted Answer

A)   in the upper left corner
B)   in the upper right corner
C)   in the lower left corner
D)   in the lower right corner

Question 20

Stars generally exhibit:

Accepted Answer

A)   an absorption spectrum.
B)   a continuous spectrum.
C)   an emission spectrum.
D)   both emission and absorption spectra.

Exam 10: Measuring the Stars