IN BRIEF

摘要

DWARF galaxies orbiting the much larger galaxy Centaurus A appear to be moving along the same plane as one another. If this coordinated dance around a galactic hub is common in the cosmos, we may have to rethink our ideas about how galaxies form. But that is a big if. Dwarf galaxies are thought to be captured by larger galaxies into random orbits based on the direction they came from. In this view, large galaxies are like hoarders, snatching up satellite galaxies and tossing them wherever. With Centaurus A, however, it is more like a collector has put them in a row on a shelf.