The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The dark absorption lines are produced by
A) the part of the low-density atmosphere that is between Earth and the surface of the star.
B) the hot, low-density atmosphere of the star emitting light in all directions.
C) all parts of the star, the stellar surface, and the atmosphere, equally.
D) the hot, dense, opaque gas of the star's surface.

Question

Quizplus · Accepted Answer

The dark absorption lines in the spectrum of P Cygni are produced by the part of the low-density atmosphere that is between Earth and the surface of the star. This atmosphere absorbs specific wavelengths of light emitted by the star, creating the absorption lines observed in its spectrum.

The Star P Cygni (In the Constellation Cygnus, the Swan)