2025年4月21日
Galaxy Lenses Galaxy from Webb
Image Credit: ESA/Webb, NASA & CSA, G. Mahler
Explanation: Is this one galaxy or two? Although it looks like one, the answer is two. One path to this happening is when a small galaxy collides with a larger galaxy and ends up in the center. But in the featured image, something more rare is going on. Here, the central light-colored elliptical galaxy is much closer than the blue and red-colored spiral galaxy that surrounds it. This can happen when near and far galaxies are exactly aligned, causing the gravity of the near galaxy to pull the light from the far galaxy around it in an effect called gravitational lensing. The featured galaxy double was taken by the Webb Space Telescope and shows a complete Einstein ring, with great detail visible for both galaxies. Galaxy lenses like this can reveal new information about the mass distribution of the foreground lens and the light distribution of the background source.
Tomorrow’s picture: terminator moon
韦伯望远镜影像: 星系替另一个星系造像
影像提供: ESA/Webb, NASA & CSA, G. Mahler
说明: 这是一个星系，还是两个？虽然乍看只有一个，其实是二个。造成这种景观的可能情况之一，是小星系撞上大星系，最后被并吞并出现在大星系的中心。但在这幅主题影像里，实际发生的是另一种更罕见的现象。影像里位于中心的淡白色椭圆星系，其距离相对于包在它周围的蓝红色螺旋星系，算是很邻近我们。影像中的景象之所以会发生，是因为近处的星系和远方的星系完美重叠，而邻近星系的引力，把远方星系发出的光拉到它的周围，形成所见的引力透镜效应。这幅呈现双重星系、其精细结构、及完整爱因斯坦环的主题影像，是由韦伯太空望远镜所拍摄。像这类的引力透镜影像，有助于天文学家取得关于星系的新资讯，诸如：前景星系的质量分布与背景天体的光分布等。
明日的图片: terminator moon
