In a groundbreaking discovery, astronomers have pinpointed two ancient streams of stars within the Milky Way, named after the Hindu deities Shiva and Shakti, offering unprecedented insights into the galaxy’s early formation. These celestial structures, identified through observations from the European Space Agency’s Gaia space telescope, are believed to be remnants of galaxies that merged with the Milky Way approximately 12 billion years ago during its formative stages.
Comprised of stars with similar chemical compositions dating back 12-13 billion years, both Shiva and Shakti possess a mass roughly 10 million times greater than the sun. The significance of their discovery extends beyond astronomy, drawing parallels with Hindu mythology where the union of Shiva and Shakti symbolises the creation of the cosmos.
Lead author Khyati Malhan of the Max Planck Institute for Astronomy in Germany remarked, “Our study addresses a very fundamental question of modern astrophysics: how do galaxies form in our universe?” Published in the Astrophysical Journal, the research sheds light on the Milky Way’s turbulent early stages.
Gaia, launched in 2013, has been instrumental in mapping the Milky Way in three dimensions, aiding researchers in detecting Shiva and Shakti through shared properties among their stars. Situated approximately 30,000 light years from the galactic center, Shiva’s stars are slightly closer to this core than Shakti’s.
These ancient star streams, differing in composition from most other stars in the galaxy, are characterized as “metal poor,” containing lesser amounts of heavier elements such as iron, carbon, and oxygen. This composition suggests they originated from the universe’s earliest stellar populations, enriching the cosmos with heavier elements through stellar explosions.
Malhan emphasised the challenge of unravelling the Milky Way’s early phases and underscored the need for future Gaia surveys, coupled with other observations, to further illuminate the galaxy’s formation and evolution. This discovery marks a significant step towards understanding the origins of our celestial home and its place in the vast expanse of the universe.