2025年6月23日
W5: Pillars of Star Formation
Image Credit: NASA, WISE, IRSA; Processing & Copyright: Francesco Antonucci
Explanation: How do stars form? Images of the star forming region W5 like those in the infrared by NASA’s Wide Field Infrared Survey Explorer (WISE, later NEOWISE) satellite provide clear clues with indications that massive stars near the center of empty cavities are older than stars near the edges. A likely reason for this is that the older stars in the center are actually triggering the formation of the younger edge stars. The triggered star formation occurs when hot outflowing gas compresses cooler gas into knots dense enough to gravitationally contract into stars. In the featured scientifically colored infrared image, spectacular pillars left slowly evaporating from the hot outflowing gas provide further visual clues. W5 is also known as Westerhout 5 (W5) and IC 1848. Together with IC 1805, the nebulas form a complex region of star formation popularly dubbed the Heart and Soul Nebulas. The featured image highlights a part of W5 spanning about 2,000 light years that is rich in star forming pillars. W5 lies about 6,500 light years away toward the constellation of Cassiopeia.
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Tomorrow’s picture: spiral spiral
W5: 恒星创生之柱
影像提供: NASA, WISE, IRSA; 影像处理与版权: Francesco Antonucci
说明: 恒星是如何诞生的？美国国家航空航天局的广域红外线巡天探测卫星（WISE，后来更名为NEOWISE），为恒星形成区W5所拍摄的这种红外光影像，提供了清楚的线索，并指出近空洞中心的大质量恒星比近边缘的恒星年龄老。可能的理由是：这些较年长的恒星触发了边缘较年轻恒星的诞生。机制可能是近中心恒星的高温外泛流，把较低温的气体压缩成物质结，当它们的密度够高时，就会发生重力塌缩形成新恒星。而在这幅依科学内涵上色的主题红外光影像里，受到高温外泛气体蒸发而孑遗下来的壮观云柱，则提供了进一步的视觉线索。影像中的天体的编录号为W5（Westerhout 5）及IC 1848。它与IC 1805所聚成的恒星形成区复合体，有心与魂星云之昵称。这幅主题影像，突显了W5约2,000光年宽、恒星创生之柱密集的区域。W5位于仙后 座方向，距离约6,500光年远之处。
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明日的图片: spiral spiral
