Emission nebula
An emission nebula was a type of nebula that emitted its own light due to the presence of ultraviolet radiation from very hot young stars inside. Cloaking devices were useless inside emission nebulae.

The Cardassian Amleth system was located within an emission nebula. ()

In 2372, Tom Paris suggested that the  travel through an emission nebula to save time. However, Chakotay rejected his proposal. ()

External link 
 

Celestial objects

de:Emissionsnebel
nl:Emissienevel