Through data gathered from the Sloan Digital Sky Survey (APOGEE) Galactic Evolution Experiment (APOGEE), scientists who have made the sort have discovered what they call a “fossil galaxy” deep in the Milky Way. Scientists say that the proposed fossil galaxy could collide with the Milky Way 10 billion years ago when our galaxy was still in its infancy. The fossil galaxy was named Heracles.
The remains of Heracles It accounts for about a third of the globular halo of the Milky Way. As for why no one noticed the presence of remnants of an ancient galaxy inside our galaxy, it is because of the depth of the Milky Way. Researcher Ricardo Schiaffon of Liverpool John Moores University says that to find the fossil galaxy, researchers had to look at the detailed chemical composition and movement of tens of thousands of stars.
Looking at so many stars is very difficult in the center of the Milky Way galaxy because it is hidden from view by giant clouds of interstellar dust. APOGEE is ideal for this type of investigation because it allows astronomers to peer into this dust and search more deeply into the core of our galaxy than ever before. APOGEE allows scientists to search through interstellar dust using near-infrared light, which is not blocked by the dust in the way that visible light does.
Finding unusual stars in the heart of the Milky Way is like finding needles in a haystack. To separate the stars belonging to Heracles from the stars in the original Milky Way galaxy, the team used the chemical composition and speed of the stars as measured by APOGEE.
Of the tens of thousands of stars examined, the researchers say, a few hundred had strikingly different compositions and chemical velocities. The researchers say that those stars were so different from the stars in the Milky Way that they could only come from another galaxy. A detailed study could allow researchers to track the exact location and history of the fossil galaxy.