One of the stars in the Big Dipper constellation is an intergalactic drifter, left behind after a collision in the distant past.
Scientists found that this particular star, known as J1124+4535, features a chemical composition that is unlike the composition of other stars in the Milky Way. Instead, it shares a similar chemistry with stars found in nearby dwarf galaxies.
In the study published in the journal Nature Astronomy, researchers suggested that this stellar alien came from a dwarf galaxy that collided with the Milky Way many years ago.
A Star That Doesn't Belong
In the survey data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, the star J1124+4535 jumped out at astronomers for its unusual chemical composition, according to the National Astronomical Observatory of Japan.
The star, which is a part of the constellation Big Dipper, featured low levels of magnesium but high levels of europium, which is a mix that has never been observed in a Milky Way star.
Stars are created from clouds of interstellar gas, so the chemical makeup of these clouds influence and leave a chemical signature on the stars that are formed from their gas.
The star J1124+4535 doesn't share a chemical signature with any other star in the galaxy, which strongly indicates that it must have formed elsewhere. Analysis shows that it shares a similar chemical composition with stars in dwarf galaxies that orbit the Milky Way.
In the bigger picture of the universe, it's not at all unusual for galaxies to crash into each other. Evolution models have demonstrated how galaxies like the Milky Way absorb dwarf galaxies around it. The researchers pointed out that there's a strong possibility the star J1124+4535 was actually part of a long-gone dwarf galaxy absorbed by the Milky Way a long time ago.
The study authors provided the clearest chemical signature so far of the galactic mergers that allowed the Milky Way to develop many billions of years ago.
Furthermore, Earth's galactic neighborhood isn't quite finished with mergers, as the Milky Way has been discovered to be on a collision course with the Andromeda galaxy.
The merger is slated to be in 4.5 billion years, but it's not expected to be a head-on collision. Instead, astronomers predict it to be a "sideswipe," with the solar system making it out unaffected due to the expansive distance between all the stars.