|Designation|| Messier 27|
|Right ascension||19h 59m 36.340s|
|Declination||22° 43′ 16.09″|
|Type of object||Planetary nebula|
|Magnitude|| Apparent Mag: +7.5|
Absolute Mag: -0.6
|Distance from Earth||1,360 ly|
|Radial velocity||-42±5 km/s|
The Dumbbell nebula, sometimes referred to as the Diabolo nebula or the Apple Core nebula, is a planetary nebula in the constellation of Vulpecula. Perhaps the best example of a planetary nebula, it was the first planetary nebula to be discovered and the second brightest. However, its greater surface brightness makes for an easier target than the Helix nebula. Its name comes from its dumbbell appearance, though it has sometimes also been compared to an hourglass figure.
Charles Messier was the first to observe the dumbbell nebula and discover this type of astronomical object. He did so in 1764. It was named the "Dumbbell nebula" in 1828 by the English astronomer, John Herschel.
Properties and Structure
At the centre of the nebula is a white dwarf star of magnitude 13.8, with a surface temperature of 85,000 K (spectral type O7). It is the largest known white dwarf, with a radius of 0.055±0.02 solar radii and a mass of 0.56±0.01 solar masses. In the outer regions is a Mira-type variable star, originally nicknamed by its discoverer, Leos Ondra, a "Goldilocks variable" in 1988. It has a long period of 213 days, with its variation in brightness caused by a cycle of expansion and contraction. While not actually in the nebula, it can be seen through the nebula due to the nebula's transparent nature.
The nebula contains many "knots", large collections of gas and dust with masses around three times that of the Earth. They vary in size between 11 and 35 billion miles, with some having "tails" and others not. The nebula is expanding at 31 km/s suggesting its age is around 3,000 to 4,000 years old, in good agreement with a young universe. The dumbbell nebula itself is around 100 times brighter than the sun.
Through large telescopes, the nebula appears white with no color, though its dumbbell structure is clear. Colour Astrophotography is required to produce the spectacular images often seen.