The Milky Way, home to the sun and billions of other stars, merged with another smaller galaxy in a vast cosmic collision roughly 10 billion years ago, scientists said on Monday based on information from the Gaia space tower.
The merging of the Milky Way and the so-called little galaxy Gaia-Enceladus expanded the bigger galaxy by around a quarter and triggered an interval of accelerated star formation lasting about 2 to 4 billion years, the scientists said.
Galaxies of all types along with the Milky Way started to form comparatively soon after the Big Bang blast that marked the beginning of the universe some 13.8 billion years in the past; however, were smaller than those seen today and have been forming stars at a speedy pace. The subsequent galactic union was effective in configuring galaxies existing today.
High-precision measurements of the position, brightness, and distance of around 1,000,000 stars within 6,500 light-years of the sun, collected by the Gaia space telescope operated by the European Space Firm, helped pinpoint stars present before the merger and those that emerged afterward.
Some stars with a higher content of elements apart from hydrogen or helium mounted in the Milky Way, they found, and others with lower such content introduced in Gaia-Enceladus, owing to its smaller mass.
While the union was dramatic and helped form what the Milky Way has become, it was not a star-destroying tragedy.
The Milky Way, spiral formed with a central bar-like structure comprised of stars, includes 100 to 400 billion stars, along with the solar, which shaped roughly 4.5 billion years in the past, far after the merger.