Gaia reveals that most Milky Way companion galaxies are newcomers to our corner of space



The Milky Way is surrounded by a number of dwarf galaxies. Most of the galaxies are named after the constellation in which they appear on the sky, for example, Draco, Sculptor or Leo. The two most obvious dwarf galaxies are the Large Magellanic Cloud and the Small Magellanic Cloud, and they are easily seen by the eye. These dwarf galaxies have been thought of as satellites for billions of years. The majority of dwarf galaxies are passing the Milky Way for the first time, according to new data from the European Space Agency. The history of the Milky Way and how it was formed is going to have to be reconsidered. The credit is given to the ESA/ Gaia/DPAC.

The data from the Gaia mission is re-writing the history of the Milky Way. Satellite galaxies to the Milky Way have been thought of as newcomers to our environment.

A dwarf galaxy is a collection of thousands of stars. For decades, it has been thought that the dwarf galaxies that surround the Milky Way are satellites and that they have been our constant companions for billions of years. The results of the data from the early third data release are surprising because the motions of these dwarf galaxies have been computed with unprecedented precision.

The movements of 40 dwarf galaxies were calculated by Franois Hammer and colleagues from across Europe and China. They used quantities known as the three-dimensional velocities for each galaxy to calculate the galaxy's energy and momentum.

The giant stars and star clusters that are known to be in the vicinity of the Milky Way are moving much slower than the galaxies. They couldn't be in the correct position around the Milky Way because of the interactions with our galaxy.

A number of dwarf galaxies have been cannibalized by our galaxy. The dwarf galaxy called Gaia-Enceladus was absorbed by the Milky Way. Its stars can be seen in the data because of their eccentric orbits and range of energies.

The Sagittarius dwarf galaxy is currently being pulled to pieces after being captured by the Milky Way more than 4 billion years ago. The stars' energy is higher than that of the other stars, which indicates that they have been influenced by the Milky Way less.

The dwarf galaxies in the new study represent the majority of the dwarf galaxies around the Milky Way. It is strongly suggested that they arrived in our vicinity in the last few billion years.

It is possible to see a smudge of light in the night sky from the southern hemisphere because of the Large Magellanic Cloud. The LMC was thought to be a satellite galaxy until the 2000s, when it was found to be traveling too fast to be bound. LMC is visiting for the first time. The same is true for most of the dwarf galaxies.

Will the newcomers settle into the atmosphere or pass us by? Franois says that some of them will be captured by the Milky Way.

It's difficult to say which ones because it depends on the exact mass of the Milky Way, and that's a quantity that is difficult for astronomy to calculate with any real accuracy. Estimates are a factor of two.

The discovery of the dwarf galaxy energies forces us to re-examine the nature of the dwarf galaxies themselves.

The Milky Way's pull will attempt to wrench it apart as a dwarf galaxy. This is a force in physics. Franois 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.

It is a death sentence for dwarf galaxies to become a companion to the Milky Way. If the dwarf had a lot of dark matter, it would not be a problem. Astronomers think that dark matter exists in the universe to provide extra gravity to hold individual galaxies together.

It was assumed that the dwarfs of the Milky Way must be dominated by dark matter to balance the force of the tidal force and keep them intact. The fact that most of the dwarf galaxies are circling the Milky Way for the first time means that they do not need to include any dark matter at all, and we must re-assess whether these systems are in balance or in the process of destruction.

The history of the Milky Way is more storied than previously thought thanks to the help of Gaia. "We hope to further tease out the fascinating chapters in our galaxy's past by investigating these intriguing clues," says Prusti.

Francois Hammer and his colleagues wrote about proper motions of dwarfs. The Astrophysical Journal has an article about velocities, total energy, and angular momentum. There is a book titled "10847/1538-4357/ac 27a8".

The Astrophysical Journal has information.

Most of the companion galaxies of the Milky Way are new to our corner of space.

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