ScienceShot: A Galaxy Tail Full of Stars

IC 3418 has a secret. At first glance, it looks like any other spiral/elliptical galaxy (right image). But take a peek at ultraviolet light (left), and you'll see that IC 3418 has a tail—one that's filled with thousands of young stars. The galaxy is located about 54 million light-years away in the middle of the immense Virgo cluster—a collection of about 1500 closely packed galaxies. So closely packed, in fact, that Virgo's gravitational tug is pulling IC 3418 through its heart at 3.6 million kilometers an hour, ripping away huge amounts of gas and trailing it behind. That gas, astronomers report this month in The Astrophysical Journal Letters, has been whipped up so much by its encounter with the intergalactic medium—like a comet's tail of ice crystals getting buffeted by the solar wind—that it has condensed into stars. The discovery offers an added benefit: astronomers will be able to study the evolution of the stars much more easily than if they had been cloaked inside their parent galaxy's clouds of dust.