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 bright, continuous part of the spectrum is produced by
A) only the part of the low-density atmosphere that is between Earth and the surface of the star.
B) the 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 bright, continuous part of a star's spectrum, such as that of P Cygni, is produced by the hot, dense, opaque gas of the star's surface. This is because the dense gas emits a continuous spectrum of light across a wide range of wavelengths.

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