Messier 76 (M76) – The Little Dumbbell Nebula

Messier 76 (M76) is a planetary nebula in the Perseus constellation approximately 3,400 light years from Earth. It’s known as the Little Dumbbell Nebula because of the shape created by its morphology—and because the larger Messier 27 is knows as the Dumbbell Nebula.

The name “planetary nebula” is a misnomer. Planetary nebulas have nothing to do with planets. Astronomers in the 18th century thought these objects were planets, but now we know differently. When a star with 80% to 800% of the sun’s mass begins to run out of hydrogen fuel, it starts fusing helium into heavier elements such as carbon and oxygen. As it does this, the additional energy from those stepped-up levels of fusion cause it to expel its outer layers.

Ultimately, the star expels all its outer layers from its core, leaving the core exposed in sort of a cosmic burp. Once all the helium is burned up, fusion ceases in the core and what is left is a giant, dense ball of carbon (about the size of the earth, but with the mass of the sun)—a diamond in the sky called a “white dwarf.” That core no longer produces new energy, but it’s still extremely hot and gives off copious amounts of radiation, ionizing the gas it expelled earlier. That cloud of gas then eventually dissipates. But before it does, the ionized gas gives off light we can record here on earth with our cameras (if the star is close enough to us).

The central bar is actually an elliptical ring that we see edge on. The nebula is bi-polar—that is, it is spewing material in both directions perpendicular to the ring. The extent that we see is about two light years across.