Most stars have hot interiors surrounded by relatively cool atmospheres. Spectrum of such a star consists of?

Question

a. white lines against a dark background

b. colored lines against a dark background

c. dark lines against a white background

d. dark lines against a colored background

Answer 1

The exterior of a star behaves roughly like a blackbody radiator, meaning it emits all colors of light in the spectrum (in different amounts).

That light passes through gasses which will block some colors of the spectrum, so if you take a spectrum of light from a star(using a spectrometer perhaps) you will see dark lines over the colors that those gasses block.

Also different elements will block light in different ways, so this is how a spectrograph tells us what elements are around a star.