I'm writing a research paper over outer space (yeah, yeah, broad topic) and I'm wondering what the proper terminology for nebula clouds is. This is an excerpt from my paper showing how I'm going to use the term: "Outer space is the host of all the types of stars and galaxies and a lot of other interesting phenomena, such as black holes, supernovas, and ________." Long story short, would I use "nebula clouds" or "nebulae"?
"nebula clouds" sound a little bit redundant, because, is there any nebula that is not a cloud?
I would stick to "nebulae". (And if you want to be consistent, you should be writing "supernovae" too).
I am not an expert on this topic, but I have never seen any use of "nebula cloud" before.
The term "nebula" has been used historically for virtually any astronomical object that was fuzzier than stars. Specifically, galaxies which to the naked eye and in small telescopes looked like elongated clouds were called nebulae (e.g. the Andromeda Nebula), even though they definitely aren't clouds.
Nowadays, the term is mostly used in the context of planetary nebulae, which are the beautifully colored death breaths of low-mass stars, lighted up by a central white dwarf. These objects were originally thought to be planets, but has nothing to do with that.
Other types of nebulae are usually called by their more descriptive names, e.g. molecular clouds, HII regions, and supernova remnants. The only objects I can think of that are often called nebulae, are reflection nebulae, which are the clouds of dust and gas surrounding a young star cluster.