On Earth, collisions rarely lead to beauty. In space, it's a different story. Astronomers in Japan say one of the best-known nebulae—the Trifid, in the constellation Sagittarius—owes its splendor to a smashup between two clouds of gas and dust. Lying roughly 7000 light-years from Earth, the Trifid Nebula consists of a red region where three dark dust lanes resemble a peace sign; an adjoining region is blue. By using telescopes in Chile, the astronomers measured Doppler shifts and thus velocities of gas in the Trifid. As the researchers will report in a future issue of The Astrophysical Journal, two gas clouds likely collided in the Trifid's red region 1 million years ago, compressing gas that collapsed to spawn new stars. One newborn star, named HD 164492, is so hot that its radiation tears electrons from protons. When the two rejoin, the electrons emit the red glow seen here. Future fireworks are forthcoming, for the star will someday explode as a supernova.
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