Scientists searching through data obtained from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) Sloan Digital Sky Survey have found what they call a “fossil galaxy” hidden away deep within the Milky Way. Scientists claim that the proposed fossil galaxy may have collided with the Milky Way 10 billion years ago when our galaxy was still in its infancy. The fossil galaxy is nicknamed Heracles.
The remains of Heracles account for around a third of the circular halo of the Milky Way. As to why nobody knew that there was a remnant of an ancient galaxy inside our galaxy, it’s because of how far inside the Milky Way it is. Researcher Ricardo Schiavon from Liverpool John Moores University claims that in order to locate a fossil galaxy, researchers had to look at the complex chemical composition and motion of tens of thousands of stars.
Looking at the many stars is extremely difficult in the middle of the Milky Way since they are obscured from view by enormous clouds of interstellar dust. APOGEE is perfect for this kind of investigation, as it helps scientists to peer further into the center of our galaxies than ever before. APOGEE helps scientists to see through space dust using near-infrared light, which is not obscured by dust like visible light is.
Finding strange stars in the center of the Milky Way is like finding needles in a haystack. In order to distinguish the Heracles from the stars in the original Milky Way, the team used both the chemical structure and the velocity of the stars as determined by APOGEE.
Researchers suggest that out of the tens of thousands of stars understudy, a few hundred had remarkably different chemical compositions and velocity. Researchers claim that the stars were so far from the stars in the Milky Way that they may only originate from another galaxy. A thorough analysis could allow researchers to map the exact location and history of fossil galaxies.