2025年4月4日
Hickson 44 in Leo
Image Credit & Copyright: Jiang Wu
Explanation: Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in this intriguing telescopic skyscape are one such group, Hickson 44. The galaxy group is about 100 million light-years distant, far beyond the spiky foreground Milky Way stars, toward the constellation Leo. The two spiral galaxies in the center of the image are edge-on NGC 3190 with its distinctive, warped dust lanes, and S-shaped NGC 3187. Along with the bright elliptical, NGC 3193 (above and left) they are also known as Arp 316. The spiral toward the lower right corner is NGC 3185, the 4th member of the Hickson group. Like other galaxies in Hickson groups, these show signs of distortion and enhanced star formation, evidence of a gravitational tug of war that will eventually result in galaxy mergers on a cosmic timescale. The merger process is now understood to be a normal part of the evolution of galaxies, including our own Milky Way. For scale, NGC 3190 is about 75,000 light-years across at the estimated distance of Hickson 44.
Tomorrow’s picture: light-weekend
狮子座的致密星系群Hickson 44
影像提供与版权: Jiang Wu
说明: 在天空中找寻星系时，加拿大天文学家希克森（Paul Hickson）和他的同事，找到100个左右的紧实星系群，因此它们有希克森致密星系群之称。于这片望远镜视野里，最吸睛的4个星系所组成的Hickson 44，是在狮子座方向的带芒银河系前景恒星后方，约1亿光年远处的致密星系群范例。影像中心的2个螺旋星系，分别是拥有扭曲尘埃带的侧向NGC 3190及S形的NGC 3187。与这二个星系为伴、位于它们左上方的，则是明亮的椭圆星系NGC 3193，而三者合起来亦称为Arp 316。影像右下角的螺旋星系NGC 3185，则是Hickson 44的第四个成员。如同其他希克森致密星系群，成员星系扭曲的外观及升高的恒星诞生活动，皆是受重力扰动的迹证，而在经过长长的宇宙尺度时间之后，终将导致星系合并。这种星系合并现象，现在咸认是星系演化的正常过程，而我们的银河系自然也不例外。作为量度尺标，以Hickson 44的估计距离来换算，星系NGC 3190的宽度约为75,000光年。
明日的图片: light-weekend
