环状星系AM 0644-741
2021年7月28日
Ring Galaxy AM 0644-741
Image Credit: NASA, ESA, Hubble, HLA; Processing: Jonathan Lodge
Explanation: The rim of the large blue galaxy at the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. AM 0644-741 is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide, they pass through each other and their individual stars rarely come into contact. The large galaxy’s ring-like shape is the result of the gravitational disruption caused by a small intruder galaxy passing through it. When this happens, interstellar gas and dust become compressed, causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond. Other galaxies in the field of view are background galaxies, not interacting with AM 0644-741. Foreground spiky stars are within our own Milky Way. But the smaller intruder galaxy is caught above and right, near the top of the frame taken by the Hubble Space Telescope. Ring galaxy AM 0644-741 lies about 300 million light years away toward the southern constellation Volans.
Tomorrow’s picture: the flower and the black hole
环状星系AM 0644-741
影像提供: NASA, ESA, Hubble, HLA; 影像处理: Jonathan Lodge
说明: 影像右侧这个泛蓝的大星系，拥有由刚诞生、极端明亮的大质量恒星所构成，直径高达150,000光年的庞大星系环。分类为环状星系的AM 0644-741，起源自一次剧烈的星系互撞。当星系互撞时，它们会穿过对方，不过它们内部的恒星鲜少发生接触。之所以会形成这种环状外观，是因为较小的星系穿过较大的星系之时，受到小星系的重力扰动所致。由于当这种互撞发生时，星际云气和尘埃会受到压缩，从而触发波浪状的恒星诞生活动，并以撞击处为为起点渐次向外传播，形成类似水塘涟漪向外扩张的景观。影像视野里的其他星系是背景星系，与AM 0644-741并无交互作用，而带星芒的恒星，则近在我们银河系之内。此外，这个闯祸的星系，位在这张哈勃太空望远镜影像的右上角附近。位在南天飞鱼座方向的环状星系AM 0644-741，离我们约3亿光年远。