Milky Way Eats Remains of Long-Lost Galaxy, ESA Gaia Spacecraft Says

The Gaia probe of the European Space Agency (ESA) has discovered evidence of a new member that entered the Milky Way some eight to 10 billion years ago.

ESA said Gaia Early Third Data Release (EDR3), which is set to be released on June 13, 2022, gathered evidence that the Milky Way ate this hitherto undiscovered galaxy.

According to the agency, the account would reveal much more extensive information on the Milky Way's past, present, and future.

A study conducted by Khyati Malhan, an astrophysicist from the Max Planck Institute for Astronomy in Heidelberg, Germany, was published in The Astrophysical Journal on Feb. 17.

The study title is "The Global Dynamical Atlas of the Milky Way Mergers: Constraints From Gaia edr3-Based Orbits of Globular Clusters, Stellar Streams, and Satellite Galaxies."

Milky Way Eats Long-Lost Galaxy "Pontus"

Milky Way consumed a previously unknown galaxy known as "Pontus," the researchers mentioned.

Pontus was a galaxy that wandered too near the Milky Way and "fell in" to our galaxy's gravity some 8 billion to 10 billion years ago, according to a statement released by the European Space Agency, which controls Gaia.

Over time, some satellite galaxies will join with our Milky Way. Modern cosmological theory predicts that galaxies will expand in mass and size through a series of mergers.

Prior research into our Milky Way has shown evidence of five mergers with previous dwarf galaxies.

This merger is essential for learning about the Milky Way because it displays "the 'family tree' of smaller galaxies that have helped create the Milky Way what it is today," according to ESA.

EarthSky said researchers looked at 170 globular clusters, 41-star streams, and 46 Milky Way satellites in all.

Aside from the Pontus event, the scientists discovered five other different merging groups (previously known to science) in the data, as well as a probable sixth.

Sagittarius, Cetus, Gaia-Sausage/Enceladus, LMS-1/Wukong, and Arjuna/Sequoia/I'itoi are the names of the five events that have previously been discovered.

Pontus and most of these other events occurred between 8 and 10 billion years ago, according to ESA, while Sagittarius is more recent, occurring between 5 and 6 billion years ago.

As a result, the Milky Way hasn't been able to entirely interrupt the Sagittarius event yet, according to the agency.

Gaia Mission

Gaia was launched into orbit nearly a decade ago, in 2013, to map the sky in three dimensions more precisely than ever before.

According to the mission team on the Gaia website, the movement of stars and other surrounding objects will disclose information on the Milky Way's composition, development, and evolution.

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