2025年8月4日
Blue Arcs Toward Andromeda
Image Credit & Copyright: Ogle et al.
Explanation: What are these gigantic blue arcs near the Andromeda Galaxy (M31)? Discovered in 2022 by amateur astronomers, the faint arcs — dubbed SDSO 1 — span nearly the same angular size as M31 itself. At first, their origin was a mystery: are they actually near the Andromeda Galaxy, or alternatively near to our Sun? Now, over 550 hours of combined exposure and a collaboration between amateur and professional astronomers has revealed strong evidence for their true nature: SDSO 1 is not intergalactic, but a new class of planetary nebula within our galaxy. Dubbed a Ghost Planetary Nebula (GPN), SDSO 1 is the first recognized member of a new subclass of faded planetary nebulas, along with seven others also recently identified. Shown in blue are extremely faint oxygen emission from the shock waves, while the surrounding red is a hydrogen-emitting trail that indicates the GPN’s age.
Tomorrow’s picture: complex stellar jumble
朝向仙女座的蓝色弧线
影像提供与版权: Ogle et al.
说明: 这些出现在仙女座星系（M31）附近的巨大蓝色弧形结构是什么？这些微弱的弧状结构由业余天文学家于2022年发现，被命名为SDSO 1，其横跨的角大小几乎与M31本身相当。起初，它们的来源是一个谜：这些结构究竟是邻近仙女座星系，还是接近我们的太阳？如今，经过总曝光时间超过550小时、业余与专业天文学家之间的合力研究，强而有力的证据显示：SDSO 1并非银河际结构，而是位于我们银河系内的一种新型行星状星云。这类天体被称为幽灵型行星状星云(Ghost Planetary Nebula, GPN)，SDSO 1是首个被确认的此类星云，并且已与另外七个新发现的相似天体一同被分类为一个崭新的子类型—逐渐消退的行星状星云。影像中所见的蓝色部分，为极其微弱的氧原子激发辐射源自冲击波产生；而周围的红色辉光则是氢原子的发射，揭示此GPN的年龄。
明日的图片: complex stellar jumble
