The space around the stars is not empty. It's surrounded by small, faint, and low in mass dwarf galaxies with as few as 1,000 stars each.
This is not new. We know from our observations of other large galaxies that they can become captured in the field of the larger object.
Astronomers have found nearly 60 smaller galaxies within the last year, though it's likely there are more hidden in the dark.
Researchers think that most of the galaxies are too new to be in the vicinity of the Milky Way.
Most dwarfs can't be long-lived satellites because of their high energies and they are at first passage, i.e., infalling less than 2 billion years ago.
There are dwarf galaxies in the space. The CC BY-SA 3.0 is for the Gaia/DPAC.
The three-dimensional positions, motions, and velocities of the stars and objects are mapped by the Gaia mission.
Hammer and his colleagues used data from the early third data release from Gaia to calculate the movements of 40 dwarf galaxies outside the Milky Way. They used parameters such as the three-dimensional velocity of each galaxy to calculate its energy and momentum.
The results showed that most of the dwarf galaxies assumed to be the Milky Way are moving much faster than other objects in the vicinity.
Over the course of its long history, the Milky Way has devoured other galaxies. The Gaia Sausage was subsumed around 9 billion years ago. Its traces are in a group of low-energy stars.
The process of incorporating the dwarf spheroidal galaxy into the Milky Way began around 4 to 5 billion years ago. The stars are flying a bit faster than the stars from the other side of the planet.
The dwarf galaxies are moving at a faster rate. The team concludes that the dwarf galaxies can't have been close to the Milky Way long enough to have been slowed down.
The researchers say that this finding could change our understanding of the interactions between normal and dwarf galaxies.
It's possible that some of the dwarf galaxies will be captured, but how long they will stay is not certain.
Hammer says that it's very easy to destroy a dwarf galaxy after a few passages because the tidal force of the Milky Way is huge.
If a dwarf galaxy can survive longer than this, something must be holding them together, such as higher concentrations of dark matter, the invisible glue that bind the Universe together.
The motions of stars can be used to hint at the presence of dark matter, which cannot be explained by the presence of normal matter alone.
The new findings suggest that dark matter doesn't need to be included in our models of these galaxies, and that future research can look at the possibility of tidal disruption with a wider set of parameters.
The researchers' results are similar to a 2006 paper that found the Large and Small Magellanic Clouds were much higher than thought, based on Hubble data. That idea has since been abandoned by some of the researchers.
There is a lot we don't know about objects in and around the Milky Way, and there's absolutely no doubt that Gaia is changing our understanding of our little corner of the Universe.
The history of the Milky Way is more storied than previously thought thanks to the work of the European Space Agency.
We hope to tease out the fascinating chapters in our galaxy's past by investigating these intriguing clues.
The research was published in a journal.
