Thousands of solar “twins” discovered by a space telescope could shed new light on how our star came to host at least one life-friendly world – and a major star walk was involved.
Researchers used data from now retired Gaia space telescopea European Space Agency observatory that mapped the motions of millions of stars in high definition from 2014 to 2025. The telescope yielded 6,594 stellar “twins” — stars with similar ages, temperatures, composition and surface gravity to the Sun — about 30 times more than previous surveys had found.
Moreover, most of these sibling stars were discovered in the Sun’s close neighborhood. Collectively, the samples tell of a mass movement of stars out of the galaxy’s crowded center over billions of years.
The article continues below
“By studying a large population of these solar twins, we found evidence to suggest that many solar twins of the same age migrated through The Milky Way around the same time as the Sun, giving us new clues as to when and how the Sun moved from its birthplace to its current location, Daisuke Taniguchian assistant professor at Tokyo Metropolitan University who led the team with Takuji Tsujimoto of the National Astronomical Observatory of Japan, told LiveScience in an email.
Migration of the stars
Taniguchi led one of the studies published Thursday (March 12) in the journal Astronomy & Astrophysics and was co-author of the second. Together, the studies suggest that when central “bar” of stars and gas in the Milky Way was formed, this process both enhanced star formation and sent a number of stars into other regions of the galaxy. This formation and “migration,” as the scientists called it, also included the sun.
“We suggest that the formation of the Milky Way’s central pole enhanced star formation and also triggered large-scale migration, leading to the formation and migration of the Sun — and many solar twins,” Taniguchi said.
Previous studies had noted that, based on its composition, the Sun must have moved at least a few thousand light years out from the galaxy’s center. But the problem is that the bar in the Milky Way acts as a “barrier” for stars moving so far away, some models show. The solution to this problem is to propose that the barrier formed only after all the stars left the region, the researchers suggested.
“This scenario, if correct, could also provide new constraints on the epoch of the Galactic bar formation,” Taniguchi said. The researchers suggested that the galaxy’s central bar took shape around 4 billion to 6 billion years ago. (The sun itself is about 4.5 billion years old, which puts it squarely within that time frame.)
Taniguchi pointed out that in the center of the Milky Way, supernovae and other types of “energetic events” tend to occur more frequently than in other regions — partly because of the extreme population density of stars there. This would make the inner parts of the galaxy potentially hostile to life. And it has implications for how life originated on Earth, as well as potentially other planets in the galaxy.
“If the Sun migrated outward relatively soon after birth, as our study suggests, the Solar System may have spent most of its history in the quieter outer disk,” Taniguchi said. “In other words, the Sun cannot have arrived in a habitable environment purely by chance, but rather as a consequence of the formation of the galactic bar.”
