The expelled outer layers of a dying star glow brightly in this true-color view of M27, the Dumbbell Nebula. Ultraviolet radiation from the star's hot, dead core energizes the surrounding gas. Over time the gas will dissipate, leaving only the core, known as a white dwarf. The nebula is about 1,360 light-years away in the constellation Vulpecula, the fox. [Bill Schoening/NOAO/AURA/NSF]
For most of its life, a star like the Sun looks a bit drab — it’s a bright, glowing orb that doesn’t change much. At the very end, though, the star puts on a spectacular show. It expels its outer layers of gas into space, forming a colorful bubble that can be sculpted into many different shapes. The bubble can last for thousands of years before its gas dissipates and fades from sight.
One of the best-known examples stands high in the south as darkness falls, in Vulpecula, the fox.
The bubble is known by several names. The most evocative is the Dumbbell Nebula; seen through a telescope, it resembles a hand weight like you’d use at the gym.
The best measurements say the nebula is about 1360 light-years away, although that distance could be off by a couple of hundred light-years in either direction.
For most of its life, the star was like the Sun, steadily burning through the nuclear fuel in its core. Now, though, it can no longer sustain those nuclear reactions, so it’s shutting down.
In response, the star’s outer layers began streaming into space about 10,000 years ago. The gas left the star in waves and clumps, producing shells of gas with embedded “knots” that can be more massive than Earth.
Although the core is no longer producing nuclear reactions, it continues to shine because it’s extremely hot. Its energy causes the escaping outer layers to glow, setting the Dumbbell ablaze with color — a brilliant final act for a star.
Script by Damond Benningfield, Copyright 2013
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