Thousands of solar “twins” discovered by space telescopes could shed new light on how our star came to host at least one life-friendly world, and whether large-scale stellar migration was involved.
The researchers used data from the Gaia Space Telescope, a now-defunct European Space Agency observatory, to record the movements of millions of stars in high resolution from 2014 to 2025. The telescope found 6,594 stellar “twins” (stars with similar age, temperature, composition, and surface gravity) to the Sun, about 30 times as many as found in previous surveys.
Furthermore, most of these sibling stars were discovered close to our Sun. Taken together, these samples reveal a mass exodus of stars from the galaxy’s dense center over billions of years.
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“By studying these large populations of solar twins, we found evidence suggesting that many solar twins of the same age migrated through the Milky Way at about the same time as the Sun, providing new clues about when and how the Sun moved from its birthplace to its current location,” Daisuke Taniguchi, assistant professor at Tokyo Metropolitan University, who co-led the team with Takuji Tsujimoto at the National Astronomical Observatory of Japan, told LiveScience in an email.
movement of stars
Taniguchi led one of the studies and co-authored the other, published Thursday (March 12) in the journal Astronomy & Astrophysics. Taken together, these studies suggest that when the Milky Way’s central “bar” of stars and gas formed, this process promoted star formation and sent many stars to other regions of the galaxy. This formation and “migration”, as the researchers called it, included the Sun.
“We propose that the formation of the Milky Way’s central bar promoted star formation and also caused large-scale migration, leading to the formation and outward migration of the Sun and many solar twins,” Taniguchi said.
Previous research had suggested that, based on its composition, the Sun must have traveled at least a few thousand light-years away from the galaxy’s center. But the problem, some models suggest, is that the Milky Way’s bars act as a “barrier” to distant stars. The solution to this problem, the scientists suggested, is to propose that the barrier only formed after all the stars had left the region.
“If this scenario is correct, it may provide new constraints on the era of galaxy bar formation,” Taniguchi said. Researchers suggested that our galaxy’s central bar formed about 4 billion to 6 billion years ago. (The sun itself is about 4.5 billion years old, so it falls right within that time period.)
Taniguchi noted that supernovae and other types of “energetic events” tend to occur more frequently at the center of the Milky Way than in other regions. This is partly due to the extremely high population density of the star. This could make the galaxy’s interior hostile to life. And that could have implications for how life originated on Earth and other planets in the galaxy.
“If the Sun migrated outward relatively soon after its birth, as our study suggests, the solar system may have spent most of its history in a quieter outer disk,” Taniguchi said. “In other words, the sun did not arrive at an environment suitable for life purely by chance, but may have come into existence as a result of the formation of a galactic bar.”
Milky Way Quiz: How much do you know about our galaxy?
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