The Red Square Nebula
Image Credit & Copyright: Peter Tuthill (Sydney U.) & James Lloyd (Cornell U.)
Explanation: How did a round star create this square nebula? No one is quite sure. The round star, known as MWC 922 and possibly part of a multiple star system, appears at the center of the Red Square Nebula. The featured image combines infrared exposures from the Hale Telescope on Mt. Palomar in California, and the Keck-2 Telescope on Mauna Kea in Hawaii. A leading progenitor hypothesis for the square nebula is that the central star or stars somehow expelled cones of gas during a late developmental stage. For MWC 922, these cones happen to incorporate nearly right angles and be visible from the sides. Supporting evidence for the cone hypothesis includes radial spokes in the image that might run along the cone walls. Researchers speculate that the cones viewed from another angle would appear similar to the gigantic rings of supernova 1987A, possibly indicating that a star in MWC 922 might one day itself explode in a similar supernova.
Tomorrow’s picture: Armstrong moon
红方块星云
影像提供与版权: Peter Tuthill (Sydney U.) & James Lloyd (Cornell U.)
说明: 什么原因让星云看起来像个方块？没人能给个明确的答案。位在红方块星云中心、名为MWC 922的恒星，可能是多星系统的成员之一。这幅主题影像，是由美国加州帕洛玛山海尔望远镜和夏威夷基亚山凯克2号望远镜的红外光影像数据组合而成。这个方形星云最可信的形成假说指出：它是处于恒星演化晚期的中心星所喷出的锥状气体，而以MWC 922的案例来说，从地球看出去，视线几乎和锥状气体喷流垂直，所以我们见到了它的侧边。支持这个锥状说的证据，包括了可能是沿着圆锥边墙发展的辐条状结构。研究人员揣测如果从别的角度看这些锥体，它们可能形似超新星1987A的庞大环状结构，这或许也在暗示MWC 922中心的恒星，将来可能也会发生类似的超新星爆炸。
明日的图片: Armstrong moon
