The Dumbbell Nebula, also known as Messier 27 (M27), is a bright, large planetary planetary nebula located in Vulpecula constellation, at a distance of 1,360 light years from Earth. It is sometimes also called the Apple Core Nebula or Diablo Nebula. The nebula has the designation NGC 6853 in the New General Catalogue. It was the first planetary nebula to be discovered.

     Charles Messier included it as M27 in his catalogue in 1764. Planetary nebulae are the remains of stars similar to our Sun. When they reach the end of their life cycle as evolved red giants, they expel their outer gaseous layers to form the nebula, which is then heated by the hot core of the central white dwarf. This will be the fate of our Sun in roughly five billion years.

     Like other planetary nebulae, the Dumbbell Nebula is formed by a central star that illuminates its expanding shell of gas, expelled by the star after it had used up all of its nuclear fuel. The central white dwarf in M27 is really just the core left from the original star, and it is extremely hot.

Planetary nebulae were named for their resemblance to the gas giants in the solar system in telescopes. They appear as small diffuse objects, not unlike the outer planets, when observed in a telescope.

     The Dumbbell Nebula has an apparent diameter of about 8 arcminutes. It has a visual magnitude of 7.5 and an absolute magnitude of -0.5, which means that the nebula has an intrinsic luminosity roughly 100 times that of the Sun. M27 can easily be seen in binoculars and small telescopes, and is a popular target among amateur astronomers.

When observed from Earth, Messier 27 appears along its equatorial plane, much like the Little Dumbbell Nebula (M76) in Perseus constellation, named for its resemblance to M27. It we could see the Dumbbell Nebula from the side, it would likely appear similar to the Ring Nebula, Messier 57, in Lyra constellation.

      The gas ejected by the central white dwarf in M27 is blocked from expanding sideways by a circumstellar disk. As a result, the gas forms two bubbles, one above and one below the disk’s plane. The Dumbbell Nebula was named for its resemblance to a dumbbell when observed in visible light. It has the shape of a prolate spheroid.

     The name goes back to the English astronomer John Herschel who described M27 as a “nebula shaped like a dumb-bell, with the elliptic outline completed by a feeble nebulous light” in 1833.

 

          Constellation Guide.