Matthew J. Graham

The center of a galaxy is a bustling metropolis where a giant black hole often snatches inattentive stars. But telescopes caught a flare in a quiet suburb, tens of thousands of light-years from the core. This gave away a wandering black hole — an invisible predator, flung out of the center after an ancient galaxy collision.

A sugar cube sits on a saucer next to a cup of hot tea. Drop it in, and it dissolves within minutes. But if you lower it slowly, the sugar melts gradually, releasing its sweetness into the drink. Something similar is happening in two newly discovered stellar pairs, except the sugar is a brown dwarf and the tea is a star.

In active galactic nuclei, supermassive black holes are surrounded by a dense ring of dust that acts like a curtain: it hides everything happening at the center. If a star ventures too close to the black hole, tidal forces tear it apart, and the resulting flare is usually visible in optical and X-ray light.