The Milky Way, the galactic home to our Sun and billions of other stars, experienced a cosmic collision with a smaller galaxy around 10 billion years ago. This significant event, based on data from the Gaia space observatory, not only increased the size of the Milky Way but also sparked a period of explosive star formation.
About Gaia Space Observatory
Gaia is a key mission that aims to develop a comprehensive three-dimensional map of our Galaxy, the Milky Way. The primary goal of this endeavour is to unveil valuable insights about the composition, formation, and evolution of the Galaxy. Utilizing its unprecedented positional and radial velocity measurements, Gaia is expected to conduct a census of roughly one billion stars in our Galaxy.
The Union of Milky Way and Gaia-Enceladus
Scientists report that the union between the Milky Way and the dwarf galaxy, known as Gaia-Enceladus, increased our galaxy’s mass by approximately a quarter. This cosmological merger triggered a period of accelerated star formation, which scientists estimate lasted between 2 to 4 billion years.
| Events | Description |
|---|---|
| Milky Way and Gaia-Enceladus Merger | Occurred approximately 10 billion years ago, increasing the Milky Way’s mass by a quarter |
| Star Formation Acceleration | Lasted between 2 to 4 billion years following the merger, due to the increased mass and resources of the combined galaxies |
Formation of Galaxies and Galactic Mergers
All types of galaxies, including the Milky Way, began forming relatively shortly after the Big Bang – the explosion event that marked the start of the universe approximately 13.8 billion years ago. However, these early galaxies were much smaller than present-day galaxies and were undergoing a rapid rate of star formation. Galactic mergers that took place subsequently played a crucial role in sculpting the configuration of existing galaxies.
Differences between Milky Way and Gaia-Enceladus Stars
In terms of content, there is a noticeable difference between stars originating from the Milky Way and those from Gaia-Enceladus. Stars containing a higher proportion of elements other than hydrogen and helium were typically formed in the Milky Way due to its larger mass. Conversely, stars with a lower content of these elements originated in Gaia-Enceladus, a reflection of its smaller mass.