An astronomer studying a particular object in space finds that it only emits light in specific emission lines?

Question

the correct conclusion is that this object???
-cannot consist of gases but must be a solid
-is made up of a hot, dense gas surrounded by a rarefied gas?
-is made up of a hot, dense gas
-is made up of a hot, low-density gas

Answer 1

I would say that it is made up of hot low-density gas. The assumption in the question is that there are no dark spectral lines. That means that there is no "black body" radiation being transmitted through a cooler gas. A hot, dense gas with strong molecular interaction would tend toward a more continuous spectrum; without dark lines there isn't a cooler gas surrounding it.

Answer 2

It is made of hot- low density gas