This false-color image shows the last gasp of a dying star. Known as M27, the Dumbbell Nebula, it is a giant cloud of gas expelled at the end of a star's life. The nebula spans more than one light-year, and will slowly fade from sight as it continues to expand in the coming millennia. It was discovered 250 years ago by Charles Messier. [George Jacoby (WIYN/NSF)]
Most stars end their lives with a blaze of color — an expanding bubble of gas and dust known as a planetary nebula.
Comet-hunting astronomer Charles Messier discovered the first planetary nebula 250 years ago today. It’s known as M27 — the 27th entry in Messier’s catalog of comet-like objects.
A planetary nebula forms when a star exhausts the nuclear fuel in its core. The core collapses to form a dense, hot cosmic ember called a white dwarf. Radiation from the white dwarf pushes away the star’s outer layers, creating an ever-expanding bubble. The radiation also causes the gas to glow like a fluorescent bulb.
As seen from afar, these clouds can look like rings, cat’s eyes, pearl necklaces, or glowing atoms. And M27 resembles a hand weight like you’d use at the gym — hence another of its names, the Dumbbell Nebula.
The Dumbbell has been expanding for thousands of years, and will remain visible for thousands of years more. Eventually, though, it will become so large and thinly spread that it’ll fade from sight. But its story won’t be done. Millions or billions of years in the future, some of the Dumbbell’s gas and dust may be incorporated into new stars and planets — an act of rebirth from the remains of a dead star.
The Dumbbell is in Vulpecula, the fox, which is high in the east at nightfall. The nebula is about halfway between Deneb and Altair, the two bright stars that mark the bottom of the Summer Triangle.
Script by Damond Benningfield, Copyright 2014
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