Madrid 2 (Europe Press)
Chinese scientists have reproduced the formation of the newly discovered Cetus stellar current around the Milky Way on a supercomputer.
“The stellar currents are remnants of dwarf galaxies of the Milky Way, but they have not been completely digested,” said Dr. Zhang Jiang of the National Astronomical Observatories of the Chinese Academy of Sciences in a statement. First author of the study.
“The process of accretion is not that the Milky Way swallowed up the dwarf galaxy in one bite, but that it shed the dwarf galaxy layer with a layer from the outside to the inside by removing the tides, like an onion peeling. The naked stars are they have dispersed into their original orbits, and they have formed.” A river-like structure, that is, a star stream. “
The Milky Way is constantly growing, devouring dwarf satellite galaxies, which is called merging galaxies. By studying the history of the Milky Way merging, we can learn how the Milky Way galaxy formed and evolved.
In their previous study, the researchers detected a Cetus stream based on observing data from the Large Area Wide Area Multi-Body Spectroscopy Telescope (LAMOST, also known as the Guoshoujing Telescope) and the Sloan Digital Sky Survey.
Now, they reconstruct the history of the formation of this stellar current on the supercomputer through a series of dynamic, high-resolution digital simulations, providing a simple image of the precursor to Cetus before it was swallowed up by the Milky Way. They publish the results in the Astrophysical Journal.
“Our work shows how the Milky Way slowly separated and swallowed up a dwarf galaxy of nearly 20 million times the mass of the sun over a period of 5 billion years,” said Professor Zhao Gang, a co-author of the study.
In satellite galaxies, there always remains a central structure consisting of relatively dense stars. Some researchers have hypothesized that NGC 5824 is a core structure associated with the Cetus current. But in this work, the researchers inverted this hypothesis using detailed numerical simulations.
“NGC 5824 is not the basic remnant of the corresponding structure of the Cetus current, because the dynamic property is incorrect,” said Zhang. “But we found that there is a strong relationship between the two. NGC 5824 should be a spherical mass in the parent galaxy of the Cetus current.”
Usually the stellar currents are distributed throughout the sky. While LAMOST helped discover the Cetus current in the northern sky, researchers have also found a candidate counterpart of Cetus current in the southern sky, the Palca current.
Professor Zhao said, “There are a lot of impacts merging into the Milky Way that are similar to the Cetus current.” “It is a treasure trove for studying the structure and history of the formation of the Milky Way, which helps us to better understand how galaxies in the universe formed and evolved.”