Swan.
To me, that doesn't rhyme.
The answer may be the "prawn nebula".
Swan Nebula
A solar nebula is related to the formation of our Solar System, any other nebula is just a nebula.
A nebula. That's composed mostly of hot gasses. Hence, the name. Hot nebula.
The helix nebula is more close than the ring nebula, as well as much brighter and larger than the ring but with low surface brightness.
Matter from nebula that condense make proto star.
Swan Nebula
no
lawn
spawn, lawn, john
Pawn
fawn
leprechaun
lawn grass
leprechaun
spawnyawnJohndrawnpawndawn, yawn, lawn and pawn
gone on lawn drawn don dawn
Not really... it rhymes with mower (as in lawn mower).