Scientists at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the French National Centre for Scientific Research (CNRS) investigated the origins of this chemical structure using advanced Auriga computer simulations. These virtual models trace how Milky Way-like galaxies evolve within a simulated universe. By analyzing 30 such galaxies, the team identified the possible processes that create the two distinct chemical patterns.

Figure 1. Milky Way’s Chemical Riddle Finally Solved.

Unraveling the Milky Way’s chemical past allows researchers to piece together how our galaxy—and others across the cosmos—developed over billions of years. This also applies to nearby systems like Andromeda, where no chemical bimodality has been observed yet. Such insights offer a window into the early universe, revealing the role of cosmic gas flows and galaxy mergers in shaping galactic evolution. Figure 1 shows Milky Way’s Chemical Riddle Finally Solved.

“Galaxies can take different routes to end up with similar results, and that variety is essential for understanding how they evolve.”

Multiple Pathways to a Two-Track Chemical Pattern

The simulations reveal that Milky Way-like galaxies can form two distinct chemical sequences through several mechanisms. In some cases, this dual pattern emerges when periods of intense star formation are followed by calmer intervals. In others, it arises from changes in the inflow of gas from the galaxy’s surroundings.

The research also revises a long-standing idea about Gaia-Sausage-Enceladus (GSE)—a smaller galaxy that merged with the Milky Way. These new results show that the GSE collision is not necessary to create the two chemical tracks. Instead, the simulations emphasize the role of metal-poor gas from the circumgalactic medium (CGM), which helps build the second family of stars.

Additionally, the specific shapes of both chemical sequences are tightly linked to each galaxy’s individual star-formation history.

New Telescopes Will Put These Ideas to the Test

With powerful observatories like the James Webb Space Telescope (JWST) and upcoming missions such as PLATO and Chronos, astronomers will soon be able to test these predictions in far greater detail and refine existing models of galaxy evolution.

“This work suggests that other galaxies should display a wide range of chemical patterns. The era of 30-meter-class telescopes will make such studies routine,” said Dr. Chervin Laporte of ICCUB-IEEC, CNRS–Observatoire de Paris, and Kavli IPMU.

“In the long run, these observations will help us better pinpoint the evolutionary pathway of our own Milky Way.”

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025), Scientists Crack the Milky Way’s Long-Standing Chemical Mystery, AnaTechMaz, pp.631