Image of a galaxy taken by the Hubble telescope, 70 million light years from Earth.



Scientists have just discovered a "galaxy fossil" present in the Milky Way.

This structure would have collided with our galaxy 10 billion years ago.

She was baptized Heracles, in reference to the hero of mythology, reports



This discovery was explained in detail in

Monthly Notices of the Royal Astronomical Society

, published on November 20.

The authors of the article explain that they have "evidence for the existence of an agglomerated structure located inside the galaxy".

Merging with our galaxy

According to the elements collected, this structure would represent a third of the spherical halo of the Milky Way.

Its merger with our galaxy could be a very important part of its history.

It is precisely its central location that made its identification so late.

"To find a fossil galaxy like this, we had to examine the detailed chemical composition and motions of tens of thousands of stars," the scientists explain.

Work all the more complicated in the center of the Milky Way, since these stars are "hidden by clouds of interstellar dust" explains the co-author of the study, Ricardo Schiavon of the Astrophysics Research Institute at the University of Liverpool John Moores (United Kingdom).

500,000 star data collected

To carry out their work, the scientists used the telescope of the Apache Point observatory in New Mexico, APOGEE ("Apache Point Observatory Galactic Evolution Experiment").

The latter, in place for ten years, has already made it possible to collect data on more than 500,000 stars in the galaxy.


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