A team of astronomers from the University of Cambridge, UK, has identified what look like nine tiny galaxies orbiting our own . Although they are not the first objects of this type to be discovered in the vicinity of the Milky Way, it is the first time that so many have been located at once.
The finding has been possible thanks to data obtained by the Dark Energy Survey project, an international initiative that tries to unravel the origin of dark energy. This enigmatic “force”, of which almost everything is unknown, could be involved in the expansion process that the universe experiences .
In fact, the discovery of these new dwarf galaxies could shed some light on another mystery that turns astrophysicists on their heads: the nature of dark matter . This imperceptible substance, from which most of the matter present in the cosmos would be made, would hold the galactic structures together.
These minigalaxias, which have been detected in the skies of the southern hemisphere, near two others already known, the Small and Large Magellanic Clouds, are a billion times dimmer than the Milky Way (some may only contain a few thousand stars, while ours is home to hundreds of billions) and a million times less massive. The closest is about 97,000 light years away , while the most distant is more than a million of them, in the constellation Eridanus.
“The discovery of so many of these satellites in such a small region of space has taken us completely by surprise,” says Sergey Koposov, the researcher at the Institute of Astronomy at the University of Cambridge who coordinated this study. “I couldn’t believe what I was seeing,” he admits. However, this expert clarifies that, at the moment, it has only been possible to confirm that three of the objects are dwarf galaxies . There are some doubts about the other six.
Thus, it could be globular clusters, groupings of stars that have the same light properties as galaxies, but are not held together thanks to the “glue” of dark matter. In this sense, although current cosmological models predict the existence of hundreds of dwarf galaxies orbiting ours (some experts suspect that it will eventually eat them up over time), their small size and the very scarce brightness they cast make it extraordinarily difficult locate them, even the closest ones .
