UGC 12591：已知自旋最快的星系

2020 February 19

UGC 12591: The Fastest Rotating Galaxy Known
Image Credit: NASA, ESA, Hubble; Processing & Copyright: Leo Shatz

Explanation: Why does this galaxy spin so fast? To start, even identifying which type of galaxy UGC 12591 is difficult — featured on the lower left, it has dark dust lanes like a spiral galaxy but a large diffuse bulge of stars like a lenticular. Surprisingly observations show that UGC 12591 spins at about 480 km/sec, almost twice as fast as our Milky Way, and the fastest rotation rate yet measured. The mass needed to hold together a galaxy spinning this fast is several times the mass of our Milky Way Galaxy. Progenitor scenarios for UGC 12591 include slow growth by accreting ambient matter, or rapid growth through a recent galaxy collision or collisions — future observations may tell. The light we see today from UGC 12591 left about 400 million years ago, when trees were first developing on Earth.

Tomorrow’s picture: open space

UGC 12591：已知自旋最快的星系
图片来源：NASA，ESA，Hubble；处理&版权：Leo Shatz

说明：为什么这个星系自旋这么快？首先，对星系UGC 12591进行分类就很困难，在左下角，它有像旋涡星系一样的黑暗尘埃带，但是它也具有透镜星系一样弥漫突起的巨大的恒星形成的核。观测得知，UGC 12591的自转速度达到了惊人的480公里/秒，几乎是我们银河系的两倍，这个速度也是迄今为止测量到的最快自转速度。旋转如此之快的星系不分崩离析，质量需要数倍于我们银河系。UGC 12591的快速自转是由于吸积周围物质造成的缓慢增加，或者最近的一次或多次星系碰撞造成的快速增加，未来的观测会给我们答案。我们现在看到的来自UGC 12591的光，是4亿年前发出的，那时的地球上刚刚开始出现树这种植物。

明日图片：open space