2019 July 28
The North America Nebula in Infrared
Image Credit & Copyright: NASA, JPL-Caltech, L. Rebull (SSC, Caltech); Optical Rollover: DSS, D. De Martin
Explanation: The North America Nebula can do what most North Americans cannot — form stars. Precisely where in the nebula these stars are forming has been mostly obscured by some of the nebula’s thick dust that is opaque to visible light. However, a view of the North America Nebula in infrared light by the orbiting Spitzer Space Telescope has peered through much of the dust and uncovered thousands of newly formed stars. Rolling your cursor over the above scientifically-colored infrared image will bring up a corresponding optical image of the same region for comparison. The infrared image neatly captures young stars in many stages of formation, from being imbedded in dense knots of gas and dust, to being surrounded by disks and emitted jets, to being clear of their birth cocoons. The North America Nebula (NGC 7000) spans about 50 light years and lies about 1,500 light years away toward the constellation of the Swan (Cygnus). Still, of all the stars known in the North America Nebula, which massive stars emit the energetic light that gives the ionized red glow is still debated.
影像提供与版权: NASA, JPL-Caltech, L. Rebull (SSC, Caltech); 可见光影像: DSS, D. De Martin
说明: 天空中的北美洲星云会形成恒星，而这正是地球的北美洲做不到之事。至于恒星形成于这团星云的那些位置，基本上被不透光的厚重尘埃给遮住了。然而，斯皮策太空望远镜为我们开了一扇新视窗，让人们可以在近红外光透视北美洲星云的尘埃，看到了数以千计的新诞生恒星。把鼠标移到上面这张根据科学内涵上色的红外线影像之上，就可以带出此区域相对应的可见光影像以供比对。这张红外光影像，很简洁地捕捉到处于不同诞生阶段的年轻恒星，从仍然隐没在云气里的致密气体和尘埃结，周围还有拱星盘和喷流的恒星，到正在清除孕育他们的茧状物之恒星。位于天鹅座方向的北美洲星云(NGC 7000)，大小约为50光年，离我们则约有1,500光年远。在所有已知的北美洲星云恒星之中，究竟是那些大质量恒星的高能星光，游离云气并激发云气发出泛红辉光，至今仍有争议。