Unveiling the Milky Way's Ancient Origins: Research Reveals Earliest Building Blocks

In a groundbreaking discovery, researchers from the Max Planck Institute for Astronomy have unveiled two of the Milky Way's earliest building blocks, shedding light on the galaxy's ancient origins. Khyati Malhan and Hans-Walter Rix have identified proto-galactic fragments named Shakti and Shiva, which merged with the Milky Way approximately 12 to 13 billion years ago during the dawn of galaxy formation.

By combining data from the Gaia astrometry satellite and the SDSS survey, the astronomers were able to trace back the origins of stars that came from other galaxies. They found that when galaxies collide and merge, the stars retain basic properties linked to their original galaxy's speed and direction. By analyzing energy, angular momentum, and metal content, astronomers can identify stars that joined the Milky Way from external sources.

The Gaia data set, launched in 2013, has revolutionized our understanding of the Milky Way's dynamics, enabling the discovery of various substructures like the Gaia Enceladus/Sausage stream and the Pontus stream. Malhan and Rix's discovery of Shakti and Shiva adds to this growing body of knowledge, providing insights into the galaxy's early evolution.

Shakti and Shiva exhibit distinct energy, angular momentum, and metallicity characteristics, suggesting they originated from separate galaxies that merged with the Milky Way billions of years ago. These proto-galactic fragments represent the initial stages of the Milky Way's growth, laying the foundation for its transformation into a vast galaxy.

The researchers' findings open a new chapter in our understanding of the Milky Way's history, highlighting the complex processes that shaped our cosmic home. With upcoming surveys like SDSS-V, 4MOST, and LSST/Rubin Observatory poised to provide additional data, astronomers are poised to uncover more secrets about the galaxy's ancient past.

Malhan and Rix's discovery of Shakti and Shiva not only expands our knowledge of the Milky Way's early building blocks but also offers a glimpse into the intricate interplay of galaxies in the vast tapestry of the universe. As astronomers continue to unravel the mysteries of our cosmic origins, these proto-galactic fragments serve as a reminder of the rich history woven into the fabric of the Milky Way.

Source: https://www.eurekalert.org/news-releases/1038574