A new study has revealed that massive galaxies have stopped making their own stars and are instead "eating" nearby galaxies and our Milky Way galaxy has grown by doing the same.
According to the research by Australian scientists, while smaller galaxies were very efficient at creating stars from gas, the most massive galaxies were much less efficient at star formation, producing hardly any new stars themselves, and instead grew by eating other galaxies.
Aaron Robotham based at The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said smaller 'dwarf' galaxies were being eaten by their larger counterparts and that all galaxies start off small and grow by collecting gas and quite efficiently turning it into stars.
He said that the Milky Way hasn't merged with another large galaxy for a long time but you can still see remnants of all the old galaxies we've cannibalized and that it's also going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds, in about four billion years.
The study was published in the journal Monthly Notices of the Royal Astronomical Society.