Remnants of Another Galaxy Found in the Milky Way

Source/Credit: Gaia spacecraft map of the Milky Way from ESA.

The European Space Agency (ESA) reported scientists found the remnants of another galaxy that collides with our galaxy 8-10 billion years ago. This would be the sixth such grouping or galaxy to be found within the Milky Way. We commonly hear about merging planets in the early stages of our solar system, but that is small stuff by comparison. Observations from ESA’s Gaia spacecraft led to this discovery. This merged galaxy is called “Pontus,” the name of one of the first children of Gaia, the Greek goddess of the Earth.

An earlier ESA release discussed the number of galaxies that arrived more recently and may pass us by or be caught by the Milky Way and pulled apart like Pontus and the others:

François Hammer, Observatoire de Paris – Université Paris Sciences et Lettres, France, and colleagues from across Europe and China, used the Gaia data to calculate the movements of 40 dwarf galaxies around the Milky Way. They did this by computing a set of quantities known as the three-dimensional velocities for each galaxy, and then using those to calculate the galaxy’s orbital energy and the angular (rotational) momentum.

They found that these galaxies are moving much faster than the giant stars and star clusters that are known to be orbiting the Milky Way. So fast, that they couldn’t be in orbit yet around the Milky Way, where interactions with our galaxy and its contents would have sapped their orbital energy and angular momentum

So will these newcomers settle into orbit or simply pass us by? “Some of them will be captured by the Milky Way and will become satellites,” says François.

I wonder what is would be like sitting in one of those smaller galaxies awaiting your fate. Of course, it will be a very long wait.

Source/Credit: Dwarf galaxies around the Milky Way from ESA.
Source/credit: Gaia spacecraft from the ESA/- C. Carreau.
Posted in ESA