The spectra of most stars are dark- line spectra because___________ .
A) elements in the earth's atmosphere absorb in these dark- line bands, blocking out the frequencies in the dark bands
B) electrons decaying to a lower energy state emit a photon at a fixed energy, leaving dark bands between the emissions
C) elements in the Sun's outer atmosphere emit radiation between these dark bands
D) elements in the Sun's outer atmosphere absorb in these dark- line bands, blocking the radiation in those bands

Question

Quizplus · Accepted Answer

The most common reason for dark-line spectra in stars is that elements in the star's outer atmosphere absorb radiation in certain specific bandwidths, leaving dark bands in the spectra. This phenomenon is known as absorption spectrum. Therefore, option D is correct as it describes this process. Option A is incorrect because it refers to Earth's atmosphere, which is not relevant to the spectrum of stars. Option B is incorrect because it describes emission spectra, which can result in bright lines, not dark lines. Option C is also incorrect because it states that the elements in the Sun's outer atmosphere emit radiation, which is not the reason for dark-line spectra.

The Spectra of Most Stars Are Dark- Line Spectra Because___________