NASA 宇宙の記録
今日の天体写真 (APOD)= カレンダーから選ぶ「宇宙の神秘」=

About 5,000 light-years away, toward the constellation Sagittarius and the center of our galaxy, lies the bright star forming region cataloged as M17. In visible light, M17's bowed and hollowed-out appearance has resulted in many popular names like the Horseshoe, Swan, Omega, and Lobster nebula. But what has sculpted this glowing gas cloud? This Chandra Observatory image of x-rays from M17 provides a clue. Many massive young stars are responsible for the pink central region of the false-color x-ray picture, their colliding stellar winds producing the multimillion degree gas cloud which extends ten or so light-years to the left. When compared with visible light images, this x-ray hot cloud is partly surrounded by the nebula's cooler gas. In fact, having carved out a central cavity the hot gas seems to be flowing out of the horseshoe shape like champagne from an uncorked bottle ... suggesting yet another name for star forming region M17.