Astronomers have found that our Milky Way started as faint, blue, low-mass object containing lots of gas. They made this observation by using NASA’s Hubble’s deep-sky surveys.
The Astrophysical Journal Letters and The Astrophysical Journal
In a recently released illustration of Milky Way, astronomers presented the Milky Way in the early stages of life. You can see the illustration in the image above.
Astronomers studied the evolution of 400 galaxies similar to the Milky Way and noted the probable evolution during a course of 11 billion years. From these studies, they found that the early Milky Way was faint, blue, low-mass object containing lots of gas to help in star birth. Blue color represents the rapid star formation.
According to the observations, Milky Way was probably a flat disk with a bulge in the middle, and then grew into a spiral shape. Bulge probably held supermassive black hole and was full of older stars while the Sun and the Earth were present in the disk.
“For the first time, we have direct images of what the Milky Way looked like in the past,” said study co-leader Pieter G. van Dokkum of Yale University in New Haven, Conn. “Of course, we can’t see the Milky Way itself in the past. We selected galaxies billions of light-years away that will evolve into galaxies like the Milky Way. By tracing the Milky Way’s siblings, we find that our galaxy built up 90 percent of its stars between 11 billion and 7 billion years ago, which is something that has not been measured directly before.”
Hubble Reveals First Pictures of Milky Way’s Formative Years – NASA (http://www.nasa.gov/press/2013/november/hubble-reveals-first-pictures-of-milky-ways-formative-years/#.UoVumflmj0s)