Astronomers Identify Remains of Long-Lost Galaxy Consumed by the Milky Way

The massive appetite of a Galaxy

The Milky Way galaxy devoured more galaxies in its early days than astronomers assumed.

The Gaia spacecraft discovered the remains of an ancient cosmic collision in our Milky Way, uncovering a formerly unidentified galaxy, now nicknamed “Pontus,” consumed by the Milky Way prior to our galaxy looking the way it does currently.

Pontus was a galaxy that drifted excessively close to the Milky Way and fell into our galaxy’s gravity around 8 billion to 10 billion years earlier causing a cosmic collisions, the European Space Agency, which commands Gaia, mentioned in a statement Thursday (Feb. 17).

Events such as this merging are essential to learning more about the Milky Way, ESA included, as it presents the ‘ancestral tree’ of smaller galaxies that have aided in making the Milky Way what it is today.

The Gaia spacecraft

Gaia launched into space close to a decade ago, in 2013, on an ambitious mission to map the sky in three dimensions more accurately than ever. Movements of stars and other bodies neighboring us will consequently expose a better understanding concerning the Milky Way’s make-up, formation and progression, mission managers claim on the Gaia website.

This latest work on galactic mergings emerged from a study of the Milky Way’s halo, an area composed of globular clusters of earlier stars, stars that have reduced metallicity, and other intriguing objects. Foreign galaxies in the halo might appear in this area in various ways, depending on the collision rate, ESA mentioned in the press release concerning the research.

The ESA specified that when a cosmic collisions occurs, immense gravitational forces called tidal forces to pull it apart. The ESA continued by adding that if this process goes gradually, the stars from the combining galaxy will create an extensive stellar stream that can be quickly identified in the halo. If the process happens rapidly, the combining galaxy’s stars will spread across the halo, and no clear signature will be visible.

The “Pontus” event

Stars are not the only means to identify a combining galaxy. If the intruder consists of globular stars or small satellite galaxies, these might additionally appear in the halo. The new research concentrated on searching for this data.

Researchers named the event after Greek mythology, which identifies Pontus as one of the first children of Gaia, the goddess of Earth.

Besides discovering the Pontus event, the group determined five additional unique merging groups (already identified by science) and a possible sixth in the data. The five already recognized occurrences are Sagittarius, Cetus, Gaia-Sausage/Enceladus, LMS-1/ Wukong, and Arjuna/Sequoia/I’itoi.

ESA mentioned that Pontus and the majority of these other cosmic collisions took place around a similar period, 8 billion to 10 billion years back. Yet, Sagittarius is more recent at 5 billion to 6 billion years earlier. The agency included that the Milky Way has not yet had the ability to disrupt it entirely.

An investigation based on the study was released Thursday (Feb. 17) in The Astrophysical Journal, led by Khyati Malhan, an astrophysicist at the Max Planck Institute for Astronomy in Heidelberg, Germany. Based on an early release of Gaia’s third large collection of data, the work is to release on June 13.

Read the original article on Space.

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