We know that stars that are part of the same cluster are chemically identical. A study now reveals that stars which were born together and then dispersed immediately rather than forming a cluster also share similar traits.
This could potentially find Sun's long-lost siblings even if they are now on the opposite side of the galaxy, it noted.
"Our Sun and its siblings, for example, probably went their own ways within a few million years after they were born," said Mark Krumholz, a professor of astronomy and astrophysics at the University of California, Santa Cruz.
The chemical uniformity of stars in the same cluster is the result of turbulent mixing of the clouds of gas where star formation occurs.
The new findings show that even stars that do not stay together in a cluster will share a chemical fingerprint with their siblings which can be used to trace them to the same birthplace.
To reach this conclusion, Krumholz and team used supercomputers to simulate two streams of interstellar gas coming together to form a cloud that, over the course of a few million years, collapses under its own gravity to make a cluster of stars.
Studies of interstellar gas show much greater variation in chemical abundances than is seen among stars within the same open star cluster.
To represent this variation, researchers added "tracer dyes" to the two gas streams in the simulations.
The results showed extreme turbulence as the two streams came together, and this turbulence effectively mixed together the tracer dyes.
"We put red dye in one stream and blue dye in the other, and by the time the cloud started to collapse and form stars, everything was purple. The resulting stars were purple as well," Krumholz said.
This explains why stars that are born together wind up having the same abundances: as the cloud that forms them is assembled, it gets thoroughly mixed.
The study was published in the journal Nature.
