I assume you mean planets eitherway interstellar dust and clouds have solid material and as well as minerals such as iron and over time solid chuncks start to fuse together and make a planet but with stars however it is different because a star has a little solid core surrounded by gasses (hydrogen and helium) to produce heat in a method called nuclear fusion so interstellar clouds contain gasses as well and solids as I previously said and form a star as well
this is from my understanding
