Closeup of the Helix Nebula. Close-up view of gas droplets in the Helix nebula. At 650 light-years away, the Helix is one of the nearest planetary nebulae to Earth. A planetary nebula is the glowing gas around a dying, Sun-like star. These expanding shells of gas from dying stars are really beautiful, and I find the physics of the way the gas is ejected to be fascinating. in the Helix the nebula is littered with dense knots of material, probably condensations in the wind blown from the dying star when it was a red giant. As the outer layers of the star blew away, they exposed deeper, hotter material. The wind from the star increased in speed, overtaking and blowing past the older material the star had emitted centuries before. When the faster wind hit denser knots of gas, it flowed around it, and also vaporized the surface material of the knots. This material then got swept downwind, blowing off the knots and forming those long, long streamers. They look a lot like comets, actually, and the physics is similar. Literally other-worldly beauty.. Credit: NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner (STScI), and T.A. Rector (NRAO).
Posted on: Mon, 31 Mar 2014 18:22:07 +0000
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