New Discovery in the History of Our Galaxy
Astronomers have made a breakthrough in understanding the formation of the Milky Way by uncovering traces of another ancient cosmic merger. Using data from the Hubble Space Telescope and the Gaia mission, an international team of researchers identified a new population of globular star clusters. These celestial bodies are not native to our galaxy but represent the remnants of a dwarf galaxy swallowed by the Milky Way in the early universe.
The study, published in the prestigious journal Nature Astronomy, confirms that about 11.8 billion years ago — just two billion years after the Big Bang — our galaxy entered into gravitational contact with a dwarf galaxy named LKH. This event became one of the key stages in the evolution of the Milky Way, defining its modern structure and chemical composition.
Scale of the Absorption and the Role of LKH
According to calculations by scientists led by Davide Massari from the Astrophysical Observatory of Bologna, the total mass of the LKH galaxy was approximately 500 million solar masses. For comparison, this is nearly comparable to the Sagittarius Dwarf Galaxy, which is currently being absorbed by the Milky Way. However, at the time of the collision, 11.8 billion years ago, the Milky Way itself was significantly smaller than it is today.
The influx of a huge amount of gas, stars, and dark matter from LKH became a decisive factor in the growth of our galaxy. This event not only increased the mass of the Milky Way but also triggered a powerful burst of star formation. The destruction of foreign stars from LKH enriched the interstellar medium with heavy chemical elements, radically changing the formation process of subsequent generations of stars, including those we see today.
Chronology of Galactic Collisions
Mergers with other galaxies are one of the main mechanisms for the growth of galactic systems; however, reconstructing the exact chronology of such events for the Milky Way is extremely difficult. Until recently, scientists were aware of a massive collision with the Gaia-Sausage-Enceladus (GSE) galaxy, which occurred approximately 10 billion years ago.
The discovery of the LKH galaxy fills an important gap in the history of the Milky Way, indicating that the active phase of "galactic cannibalism" began even earlier than previously thought. New measurements allowed researchers to separate LKH stars from other populations, made possible by the high precision of data obtained via Hubble and Gaia.
Contradictory Data
During the analysis of sources, minor discrepancies were identified in the interpretation of the name and characteristics of the absorbed galaxy. While the scientific study and major sources (RBC-Ukraine, Rambler) use the abbreviation LKH, some publications (specifically Pravda.ru) mention the name "Loki." This may indicate an alternative name for the galaxy used in different scientific circles or an inaccuracy in the initial reports.
Furthermore, there is a nuance in the assessment of the timing of the event: some sources cite the exact figure of 11.8 billion years, while others give the rounded value of "almost 12 billion years." Despite these differences, all sources agree that the event occurred in the early universe and was fundamental to the formation of the Milky Way.
