2025年10月31日
仙后座的幽灵
影像提供与版权: Alex Rodriguez
说明: 万圣节是天文节日，而在地球的夜空中，总是会出现一些神秘诡异的形状。事实上，在这张朝向仙后座方向的望远镜视野中心附近，这两片向后扫的星际云IC 59（左）和IC 63在宇宙尺度上看起来如同幽灵。它们距离约600光年，但实际上这些云并非幽灵。不过，在炽热明亮恒星仙后座γ星的高能量辐射影响下，它们正在慢慢消失。画面中最亮的蓝色恒星，仙后座γ，实际上距离这些星云只有3到4光年。距离仙后座γ稍近的IC 63主要由红色的Hα光主导，这是因为氢原子被热恒星的紫外线辐射游离后，重新与电子结合所发出的光。距离恒星较远的IC 59也显示出Hα发射线，两个星云都因为尘埃反射星光而呈现出特有的蓝色光芒。视野范围约为2度，或以星际幻影的距离估计，约为20光年。
明日的图片: seven spooky sisters
Due to the lapse in federal government funding, NASA is not updating APOD website. We sincerely regret this inconvenience.
由于美国联邦政府资金中断，NASA目前暂停更新APOD网站。对此带来的不便，我们深感抱歉。
英文原文:
Explanation: Halloween is an astronomy holiday and spooky shapes always seem to lurk in in planet Earth’s night skies. In fact, near the center of this telescopic view toward the constellation Cassiopeia these swept-back interstellar clouds IC 59 (left) and IC 63 look ghostly on a cosmic scale. About 600 light-years distant, the clouds aren’t actually ghosts. They are slowly disappearing though, under the influence of energetic radiation from hot, luminous star gamma Cas. The brightest bluish star in the frame, Gamma Cas is physically located only 3 to 4 light-years from the nebulae. Slightly closer to gamma Cas, IC 63 is dominated by red H-alpha light emitted as hydrogen atoms ionized by the hot star’s ultraviolet radiation recombine with electrons. Farther from the star IC 59 also shows H-alpha emission, and both nebulae shine with the characteristic blue tint of dust reflected star light. The field of view spans about 2 degrees or 20 light-years at the estimated distance of the interstellar apparitions.
