The Sun may have been part of a small group of stars that migrated from the core of our galaxy between 4 and 6 billion years ago, passing through what is now an impassable barrier on its journey to a more habitable region of the Milky Way.
The new research, conducted by astronomers at Tokyo Metropolitan University, used data from the European Space Agency’s Gaia satellite to produce the most accurate catalogue of solar twins ever assembled. Their detailed analysis of the star catalogue, reported in a recent paper published in Astronomy & Astrophysics, provides astronomers with crucial new information about the Milky Way’s evolution and bar-like central structure, shedding light on how the ancient cosmic escape occurred.
Origin of the Sun
Astronomers previously believed that our Sun formed about 10,000 light-years closer to the galactic center than its current position roughly 4.6 billion years ago.
However, how this migration occurred has long remained a question for researchers. Analysis of stellar composition suggests that stars like the Sun formed in a more central location, yet today a structure known as the corotation barrier appears to impede their movement outward from the galactic center.
“The physical mechanism behind the corotation barrier has been fairly well understood,” co-author Dr. Daisuke Taniguchi, of Tokyo Metropolitan University, told The Debrief. “However, what has been less clear is where exactly the barrier may have been located in the past.”
The researchers focused their study on solar “twins,” stars with temperatures, surface gravities, and chemical compositions similar to those of our Sun. Among the nearly two billion stars contained in the Gaia data set, the team identified 6,594 solar twins—roughly 30 times more such stellar analogues than had been found in previous studies.
Developing a Star Catalogue
“We selected stars whose atmospheric parameters (surface temperature, surface gravity, and metallicity) are very close to those of the Sun,” Taniguchi explained. “In addition, we applied several quality cuts using other physical parameters and data flags to ensure that only high-quality measurements were included in our final sample.”
The large sample size enabled the researchers to determine the stars’ ages with much greater precision than earlier work allowed. Their analysis suggests that the formation of these types of stars peaked roughly 4 to 6 billion years ago, providing evidence that many may have formed in the same region near the center of the Milky Way.
The research also offers clues about the evolution of the galaxy’s central structure. Today, the corotation barrier associated with the Milky Way’s bar would prevent stars from migrating outward in the way the Sun appears to have done.
This suggests that the migration likely occurred before the barrier reached its current position. In other words, the corotation barrier itself may have shifted over time as the galaxy evolved.
“Our study proposed the possibility that the location of the barrier may have changed significantly around 4-6 billion years ago,” Taniguchi said. “If so, this could have allowed stars like the Sun to migrate outward more easily during that period.”
Further Research on Sun Twins
For life on Earth, it may be fortunate that the Sun migrated away from the galactic center before the corotation barrier stabilized, since the central regions of the Milky Way present a far more hostile environment for planetary systems.
The researchers plan to continue expanding their solar twin catalogue as new astronomical data becomes available.
“A natural next step will be to expand the sample using the upcoming Gaia DR4 data release planned for December 2026 (in this study, we used Gaia DR3 data),” Dr. Taniguchi said. “With a larger number of Solar twins and a wider observational volume (currently 6,594 Solar twins within about 1,000 light years around the Sun), we can improve the statistical significance of the results and also further investigate the spatial distribution of the sample.”
The team hopes their star catalogue will help other astronomers pursue new lines of research.
“Our catalog is currently the largest high-confidence catalog of Solar twins and contains a wide range of information, including ages, chemical compositions, distances, and other stellar properties,” Dr. Taniguchi concluded. “Because of this, I hope it will be used for many different kinds of studies beyond the questions we explored in our papers.”
The paper, “Solar Twins in Gaia DR3 GSP-Spec I. Building a Large Catalog of Solar Twins with Ages,” appeared in Astronomy & Astrophysics on March 12, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.