The Gaia space telescope has recently made a groundbreaking discovery that is shedding new light on the early history of our galaxy, the Milky Way. By tracking the motions of billions of stars in our galaxy, Gaia has uncovered two ancient streams of stars named Shakti and Shiva, believed to have formed over 12 billion years ago.
These streams are thought to have developed before the Milky Way’s spiral arms or extended disk. Named after Hindu gods who united to create the universe, Shakti and Shiva are considered “protogalactic fragments” in the heart of the Milky Way, with stars between 12 and 13 billion years old.
What sets Shakti and Shiva apart is the difference in the orbits and compositions of their individual stars. Stars in Shiva have more circular orbits and are closer to the center of the Milky Way compared to those in Shakti. This discovery was made possible by the detailed data gathered by Gaia, allowing researchers to determine the orbits and compositions of stars on an individual level.
The implications of this discovery are vast, as it is helping astronomers piece together the early history of our galaxy and build a stellar family tree. The research, which was published in the Astrophysical Journal on March 21, 2024, marks a significant step forward in our understanding of the Milky Way’s formation and evolution. With Gaia’s continued observations, who knows what other secrets of our galaxy will be unveiled in the future.
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