A team of scientists has managed to come up with the MOST DETAILED image of our galaxy, the Milky Way during its earliest days. The fascinating map shows –in 3D— how our galaxy formed some 13.5 billion years ago and how hundreds of thousands of stars joined together forming the Milky Way.
Astrophysicists were able to identify approximate age of around 130,000 stars in the Milky Way’s halo based on the color which they ultimately used to create the model we see below. The Oldest stars are located at the center of the Milky Way.
Researchers from the University of Notre Dame Daniela Carollo, Timothy Beers and Vinicius Placco published their findings in the journal Nature Physics, including a chronographic map that supports a hierarchical model of galaxy formation.
This model, developed by theorists in recent decades, suggests that the Milky Way formed by the melting and accumulation of small mini-halos containing stars and gas.
Their model suggests that the oldest stars in the Milky Way are located in the galactic center and that young stars and galaxies MERGED with the Milky Way, attracted by gravity, for a period of billions of years.
“We haven’t previously known much about the age of the most ancient component of the Milky Way, which is the Halo System,’ says Daniela Carollo, a Notre Dame astrophysicist. But now we have demonstrated conclusively for the first time that ancient stars are in the center of the galaxy and the younger stars are found at longer distances. This is another piece of information that we can use to understand the assembly process of the galaxy, and how galaxies in general formed.”
Using data from the Sloan Digital Sky Survey, scientists identified more than 130,000 blue stars of the horizontal branch, burning helium in their cores. These stars exhibit different colors depending on their age. They are the only type of star whose age can be estimated by their color.
The selected stars show a clear hierarchy, with the oldest near the center of the galaxy, and the youngest further.
“The colors, when the stars are at that stage of their evolution, are directly related to the amount of time that star has been alive, so we can estimate the age,’ says Timothy Beers, Notre Dame Chair of Astrophysics, who helped develop the identification technique about 25 years ago. Once you have a map, then you can determine which stars came in first and the ages of those portions of the galaxy.”
According to experts, it is only feasible to use this sort of technique while studying our own galaxy and surrounding dwarf galaxies. However, researchers expect that the James Webb Space Telescope, set to launch in 2018 will gather more data of far more distant galaxies which would eventually help scientists take a peek at the first glimmerings of the ‘Big Bang’.
Using the new method, scientists can utilize data which will allow them to fill the pieces on the formation of our galaxy and how the universe itself arose.
“We can now actually visualize how our galaxy was built up and inspect the stellar debris from some of the other small galaxies being destroyed by their interaction with ours during its assembly,” added Timothy Beers.