Ninety percent of all normal stars in a Hertzsprung-Russell (H-R) diagram are:
A) in the giant region.
B) in the supergiant region.
C) on the random sequence.
D) on the main sequence.
Question 2
Which of the following systems cannot be analyzed as a visual binary?
A) Binary stars that are separately visible in a telescope
B) Binary stars that are about 2 AU apart
C) Binary star systems having orbital periods of hundreds or thousands of years
D) Binary stars orbiting so close to each other that they are not visible as separate stars