Researchers at the Max Planck Institute for Astronomy in Germany have identified “promising candidates” that may serve as evidence of the early days of the Milky Way. The results were published in the Astrophysical Journal.
Named “Shakti” and “Shiva”, the two new structures announced by the scientists appear to be remnants of two galaxies that merged with the early version of the Milky Way between 12 and 13 billion years ago, directly participating in the initial development phase of the Milky Way.
“Shakti” and “Shiva” appear to be remnants of two galaxies that merged with the early version of the Milky Way between 12 and 13 billion years ago. (Image: NASA).
The authors suggest that this research outcome can be understood similarly to how archaeologists identify traces of an early settlement that developed into a large city today.
So far, it has not been possible to determine which stars originated from which precursor galaxies following the merger. However, according to the research institute, most stars still retain fundamental characteristics, “directly related to the speed and origin of the galaxies”. By utilizing “fundamental physics,” the researchers discovered large star clusters with unusually comparable energy and angular momentum values, which are related to motion or orbital rotation. This indicates that these may be remnants of a merger process. The very low metallicity of the stars further supports the hypothesis that they existed in the early days of the Milky Way.
The Max Planck Institute stated that thanks to the Gaia space observatory by the European Space Agency, researchers have obtained a “large and high-quality dataset.” Launched in 2013, this satellite is considered to have initiated a “revolution” in the study of stellar dynamics within the Milky Way, generating increasingly accurate datasets that include the positions, positional changes, and distances of nearly 1.5 billion stars.
Currently, the researchers have identified the aforementioned two structures by combining data from the Gaia satellite with stellar spectra from the Sloan Digital Sky Survey, providing insights into the chemical composition of the stars. The researchers believe that conducting additional new surveys will yield even more relevant data.
According to the institute, if both the spectra and accurate distances are known, astronomers will be able to definitively conclude whether Shakti and Shiva are indeed structures that open up the first insights into the primordial history of the Milky Way.
