ESO, ESA/Hubble, NASA. Digitized Sky Survey/Davide de Martin
The dwarf galaxies orbiting the much larger galaxy Centaurus A appear to be moving along the same plane as one another. If this surprisingly coordinated dance around a galactic hub is common across the cosmos, we may have to go back to the drawing board on galaxy formation theory.
But that’s a big, big if. Theories on galaxy formation suggest that dwarf galaxies should 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.
In Centaurus A, however, it is more like a collector has neatly put them in a row on a shelf.
Oliver Müller at the University of Basel, Switzerland, led a team who found that 14 out of 16 known