Ancient Star Streams Illuminate the Milky Way's Expansion:
The European Space Agency (ESA) has unveiled groundbreaking discoveries shedding light on the Milky Way's rich history. Through its Gaia space telescope, the ESA uncovered two ancient streams of stars that intertwined and merged with the Milky Way in its early stages of development. Referred to as Shakti and Shiva, after the divine Hindu couple believed to have united to create the universe, these streams offer valuable insights into the galaxy's formation.
The researchers stumbled upon the streams while analyzing data collected by Gaia, a feat that underscores Gaia's mission to unravel the Milky Way's origins. Timo Prusti, Gaia's project scientist at the ESA, emphasized the importance of distinguishing subtle differences among stars in the Milky Way to comprehend the galaxy's evolution accurately. Gaia's precise data has been instrumental in achieving this goal.
Scholars speculate that Shakti and Shiva predates even the oldest segments of the Milky Way's spiral arms and disc, making them approximately 12 to 13 billion years old. Each stream comprises stars equivalent to the mass of about 10 million Suns. Although the star streams are positioned close to the Milky Way's core, they are not directly aligned with it. Gaia's 2022 data collection in this region revealed the presence of the galaxy's most ancient stars.
Hans-Walter Rix, a researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany, and a co-author of the study published in the journal Nature, remarked on the significance of Shakti and Shiva. He noted that these streams represent early stages of the Milky Way's expansion toward its current scale. Khyati Malhan, another co-author, emphasized the transformative changes the Milky Way has undergone since the birth of Shakti and Shiva's stars, underscoring the unexpected clarity of the structures visible today due to Gaia's unprecedented data.
While Shakti and Shiva share similarities, such as their age and positioning relative to the Milky Way, there are distinctions in their orbital patterns. Shakti's stars orbit slightly farther from the galactic center in more circular trajectories compared to Shiva's. This implies that Shakti and Shiva played integral roles in the galaxy's formation, likely emerging from the amalgamation of gas and dust filaments eons ago.
As scientists continue to delve into the complexities of the Milky Way's evolution, the ESA anticipates that forthcoming Gaia data releases will unveil further revelations. The ancient star streams of Shakti and Shiva serve as celestial markers illuminating the Milky Way's evolutionary journey.
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