Astronomers have discovered 3 ancient stars in the outskirts of the Milky Way galaxy that are moving in the “wrong direction” at high speeds of hundreds of thousands of miles per hour.
These stars are 12-13 billion years old, making them as old as the first galaxies formed after the Big Bang.
They were found in the Milky Way’s halo and are dubbed “SASS” stars, which stands for “Small Accreted Stellar System” stars.
It is believed these stars formed in their own small, primitive galaxies that were later absorbed by the Milky Way. Studying them provides insights into the early universe.
The stars were discovered by MIT professor Anna Frebel and her students as part of a new course on studying ancient stars. They analyzed existing telescope data.
Analysis of the stars’ chemical composition and orbits showed they originated from other galaxies and are now migrating through the Milky Way halo in retrograde orbits.
Studying more of these ancient “intruder” stars could provide a window into understanding the first stars and galaxies that formed in the early universe.
Source: Space