The object you are observing through a telescope appears visually to be a single star,but you know by looking at its spectrum that it is a binary system.Which spectral feature might NOT characterize it as a binary?
A) The spectrum includes spectral lines associated with two different spectral types.
B) The sets of spectral lines move periodically to slightly higher frequencies and then slightly lower frequencies.
C) As the lines from one spectral type are moving toward higher frequencies, the lines from the other spectral type are moving toward lower frequencies.
D) The spectral lines from one spectral type become periodically brighter, while the lines from the other spectral type become dimmer.

Question

Quizplus · Accepted Answer

Option D is the correct choice because it describes a phenomenon known as "line doubling," which is commonly observed in binary stars where one component is significantly brighter than the other. This effect is caused by the periodic variation of the spectral lines from one spectral type becoming brighter and the lines from the other spectral type becoming dimmer. Therefore, it is the only option that does not directly characterize the system as a binary. Options A, B, and C all describe characteristic features of binary systems in which multiple spectral types are present and are moving periodically with respect to each other.

The Object You Are Observing Through a Telescope Appears Visually