哈勃望远镜看到一个合并的星系
This new NASA Hubble Space Telescope image shows ESO 185-IG013, a luminous blue compact galaxy (BCG). BCGs are nearby galaxies that show an intense burst of star formation. They are unusually blue in visible light, which sets them apart from other high-starburst galaxies that emit more infrared light. Astrophysicists study BCGs because they provide a relatively close-by equivalent for galaxies from the early universe. This means that BCGs can help scientists learn about galaxy formation and evolution that may have been happening billions of years ago.
Hubble imaged ESO 185-IG013 in ultraviolet, visible, and infrared wavelengths to reveal details about its past. Hundreds of young star clusters, many of which are younger than 100 million years, populate the galaxy. A large number of star clusters are only 3.5 million years old – relative infants compared to the timescale of our universe. Scientists predict that many of these youngest clusters will not last, since young clusters can often perish after expelling too much of their gas. The large number of young star clusters indicates that this galaxy was part of a recent galaxy collision and merger. The perturbed structure of the galaxy, which likely occurred from the violent interactions of gas and dust during the collision, is another sign. The merger supplied the system with lots of fuel for star formation, which continues to take place today.
ESO 185-IG013 also contains a tidal shell, the diffuse glow surrounding its bright center, which is a common signal of galaxy mergers. Scientists believe that in a galaxy merger, the smaller of the two interacting galaxies gets disrupted by the larger galaxy, losing most of its material. This releases the material, which then gets pulled in again by the gravity of the larger galaxy. The dense area where the material gets repositioned is called the shell, and it contains many star clusters. In addition to the shell, ESO 185-IG013 boasts a tail of gas in the northeast.
All of the stars in the system have a combined mass more than 7 billion times that of our Sun. The system is located about 260 million light-years away.
这张新的NASA哈勃太空望远镜图像显示了ESO 185-IG013，一个明亮的蓝色致密星系（BCG）。BCGs是近邻星系，显示出强烈的恒星形成爆发。它们在可见光下呈现出不同寻常的蓝色，这使它们与其他发射更多红外光的高星暴星系区别开来。天体物理学家之所以研究BCGs，是因为它们为早期宇宙中的星系提供了相对近距离的等量物。这意味着BCGs可以帮助科学家了解数十亿年前可能发生的星系形成和演化。
哈勃在紫外线、可见光和红外波段对ESO 185-IG013进行了拍摄，以揭示其过去的细节。银河系中有数百个年轻的星团，其中许多年龄不到1亿年。大量的星团只有350万年的历史——与我们宇宙的时间尺度相比，相对来说还是婴儿。科学家们预测，许多这些最年轻的星团不会持续太久，因为年轻的星团在排出太多气体后往往会消亡。大量的年轻星团表明这个星系是最近星系碰撞和合并的一部分。星系的扰动结构是另一个迹象，它可能是由碰撞过程中气体和尘埃的剧烈相互作用造成的。这次合并为恒星的形成提供了大量的燃料，这一过程一直持续到今天。
ESO 185-IG013还包含一个潮汐壳，即围绕其明亮中心的漫射辉光，这是星系合并的常见信号。科学家认为，在星系合并中，两个相互作用的星系中较小的一个被较大的星系破坏，失去了大部分物质。这释放出物质，然后被更大的星系的引力再次吸引。物质重新定位的密集区域被称为壳层，它包含许多星团。除了外壳之外，ESO 185-IG013还在东北部拥有一条气尾。
该系统中所有恒星的总质量都是太阳的70亿倍以上。该系统距离地球约2.6亿光年。