A team of researchers from China and Canada reported the discovery of the remnants of the original stellar disk from which our Milky Way galaxy later evolved.
The results of the research suggest that the Milky Way began its life as a small galaxy. Over time, it pulled in many other galaxies and grew significantly in size. Astronomers find remnants of these galaxies throughout the Milky Way, making it much more difficult for them to determine the structure and age of its original stellar disk.
The international team of researchers studied a large number of stars in different corners of our galaxy to find the answer to this question. They looked for luminaries with similar ages and orbital characteristics. They were able to identify a group that they believe is part of the very original disk from which our Milky Way evolved. The team has named this disk PanGu.
The study revealed that the oldest PanGU stars formed more than 13 billion years ago. This contradicts previous models, according to which the first structure of the Milky Way emerged about 12.5 billion years ago.
Scientists estimate that the mass of the Milky Way’s original core was 3.7 billion solar masses. It wasn’t fully a disk: its height at an early stage was almost equal to its diameter. However, over time it became flatter with little change in length and width. Scientists believe that the ancient Milky Way reached the peak of star formation about 11 billion years ago. That’s when our galaxy reached its current size.
It is worth noting that the present-day mass of PanGu is about 2.2 billion solar masses, which is only 0.2% of the current mass of our galaxy. This clearly demonstrates how strongly the Milky Way is made up of material from other galaxies it has absorbed.
Recall that earlier astronomers published the most detailed infrared map of the Milky Way.
According to Phys.org
