'Red nuggets' are compact galaxies packed with stars. They could represent the initial building blocks for some of the enormous elliptical galaxies astronomers see throughout the universe.
Hubble/European Space Agency/NASA/REUTERS
Mining the archives of two major observatories, a team of astronomers has uncovered what could be a mother lode of "red nuggets" – a type of galaxy that could represent the initial building blocks for some of the enormous elliptical galaxies astronomers see throughout the universe.
Such ellipticals represent the final stages of galaxy evolution, where the vast collection of stars they contain are old and few if any new stars are forming. Some are thought to form through the mergers of large spiral galaxies such as the Milky Way.
But since the initial discovery of red nuggets, astronomers suggest that giant ellipticals also may form with red nuggets as the seeds that over time also grow through mergers with other galaxies.
Despite their small size, it's hard not to see why red nuggets can be so attractive, gravitationally speaking.
Red nuggets are compact galaxies. They can be as small as 10 percent of the Milky Way's size. But their small size belies the large number of stars they contain. The mass of all the stars a red nugget contains can run to more than 10 times the mass of all the stars in the Milky Way.
More important, current models of galaxy formation and evolution can't account for their existence, especially in the early universe, researchers say.