A ‘fossil galaxy’ hidden in the depths of our own Milky Way

A new find out about might revolutionize our working out of how the Milky Way grew into the galaxy we see lately. It suggests {that a} “fossil galaxy” is hidden in the depths of our own Milky Way.

The results come from knowledge seen from the Sloan Digital Sky Surveys’ Apache Point Observatory Galactic Evolution Experiment (APOGEE).

According to astronomers, this fossil galaxy would possibly have collided with the Milky Way ten billion years in the past. Astronomers dubbed this fossil galaxy as Heracles after the historical Greek hero won the present of immortality when the Milky Way used to be created.

The remnants of Heracles constitute round one-third of the Milky Way’s round halo. Yet, on the off probability that stars and gasoline from Heracles make up one of these massive share of the galactic halo, why did we leave out it? The solution lies in its location someplace within the Milky Way.

Ricardo Schiavon from Liverpool John Moores University (LJMU) in the UK, an important member of the analysis workforce, mentioned, “To find a fossil galaxy like this one, we had to look at the detailed chemical makeup and motions of tens of thousands of stars. That is especially hard to do for stars in the Milky Way center because they are hidden from view by clouds of interstellar dust. APOGEE lets us pierce through that dust and see deeper into the heart of the Milky Way than ever before.”

Graduate scholar Danny Horta from LJMU, the lead writer of the paper pronouncing the outcome, explains, “examining such a large number of stars is necessary to find unusual stars in the densely-populated heart of the Milky Way, which is like finding needles in a haystack.”

The workforce used chemical compositions and velocities of stars measured through the APOGEE instrument- to split stars belonging to Heracles from the ones of the authentic Milky Way.

Horta mentioned, “Of the tens of thousands of stars we looked at, a few hundred had strikingly different chemical compositions and velocities. These stars are so different that they could only have come from another galaxy. By studying them in detail, we could trace out the precise location and history of this fossil galaxy.”

Stars that belong to this fossil galaxy account for more or less one-third of the whole Milky Way halo mass. It approach this newly-discovered historical collision should were a significant tournament in the historical past of our galaxy.

Schiavon mentioned, “As our cosmic home, the Milky Way is already special to us, but this ancient galaxy buried within makes it even more special.”

Karen Masters, the Spokesperson for SDSS-IV, feedback, “APOGEE is one of the flagship surveys of the fourth phase of SDSS, and this result is an example of the amazing science that anyone can do, now that we have almost completed our ten-year mission.”

Journal Reference:

Evidence from APOGEE for the Presence of a Major Building Block of the Halo Buried in the Inner Galaxy,” Danny Horta et al., 2020 Nov. 20, Monthly Notices of the Royal Astronomical Society: arxiv.org/abs/2007.10374

About the author

Kanishk Singh

Kanishk Singh

Kanishk is a passionate blogger and has been working with many websites as the content writer and editor. Besides, he has also written guest editorials in local magazines. Contact him at kanishk@indiacolumnist.com

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