We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with column densities derived from resonance absorption lines viewed against the ...

Little Dumbbell Nebula (also known as Messier 76, M76, or NGC 650/651) located 3,400 light-years away in the northern circumpolar constellation Perseus. It is classified as a planetary nebula, an ...

The Iris is a reflection nebula, a cloud of gas and dust illuminated by a central star. It's six light-years across, and lies 1400 years away from the earth. The Eagle Nebula is a young open cluster ...

The red nebula is a merger of two massive emission nebulae. The nebula at the head position, NGC2327, and the nebula that appears to be the wings, IC2177, take on the shape of a seagull or duck.