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Astronomers- Milky Way Once Destroyed Complete Galaxy

Astronomers- Milky Way Once Destroyed Complete Galaxy

Astronomers previously believed that the galaxy was made from two separate units of stars, however exactly how or after they came together was a mystery. Using the Gaia space telescope, these researchers were able to take more precise measurements of the position, brightness and distance of roughly one million stars. The study was published today in the journal Nature Astronomy. According to a new study, the Milky Way "ate" Gaia-Enceladus, after the nearby dwarf galaxy collided and merged with our galaxy in the past.

The chemical composition of the Milky Way's stars suggests a significant merger in the past. Applying same tools from an earlier study, Brent Tully from the University of Hawaii and his global team of astronomers have been able to map the size and shape of an extensive empty region they called the Local Void that borders the Milky Way galaxy. But if both components were formed at the same time, what differentiates one from the other? The blue stars acted as evidence.

Dwarf galaxies merged in the early universe to form the larger galaxies that populate it today, including the Milky Way. Stars that are redder in appearance due to their higher metal content trace the original stars formed in the galaxy pre-merger.

Being able to determine the ages of the stars using the Gaia telescope allowed the researchers to better simulate the early life of the Milky Way, supporting the theory that our galaxy swallowed up a smaller one. The early Milky Way was four times more massive and contained more metal.

"Primitive milky way formed stars in the past three billion years".

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"The sharp halo age distribution cut-off at 10bn years ago can be identified with the time of accretion of Gaia-Enceladus to the Milky Way".

Other distant galaxies bear clues about mergers that happened billions of years ago, visible as distortions in a galaxy's overall shape. Eventually, the galaxy's gas created a thin disc that it still maintains.

Although we live in a cosmic metropolis, back in 1987 University of Hawaii astronomer Brent Tully and NRAO astronomer Richard Fisher noted that the Milky Way is also at the edge of an extensive empty region that they called the Local Void.

"We have analyzed, and compared with theoretical models, the distribution of colours and magnitudes (brightnesses) of the stars in the Milky Way, splitting them into several components; the so-called stellar halo (a spherical structure which surrounds spiral galaxies) and the thick disc (stars forming the disc of our Galaxy, but occupying a certain height range)", IAC researcher and study author Carme Gallart said in a statement.

Now, thanks to Gaia data, astronomers have a more complete picture of our galaxy's past.