The first large age map has been constructed that features the history of the Milky Way.
Astronomers have found out about the life spans of over 70,000 stars spread out in the Milky Way. The resultant age map shows the galaxy in a colorful display.
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For one thing, the hypothesis has been ratified that our galaxy’s growth started in the middle and worked its way outwards. The oldest stars are towards the center of the Milky Way. This happens to be the largest such map ever assembled by astronomers.
This first age map of Milky Way is being presented at the 227th meeting of the American Astronomical Society in Florida.
Lead researcher Melissa Ness told the BBC, “We’re characterizing in really unprecedented detail how the galaxy is formed via this snapshot of stellar ages across the disc.”
"And we not only have these ages in the plane of the disc, but also moving up above the galactic plane," added Dr Ness, who works at the Max Planck Institute for Astronomy in Germany.
The wisps and offshoots of the map lead off from the earth. In order to find out the age of each star, two telescopes were used simultaneously. The Apogee project tested the light coming from thousands of stars.
Over 300 were sampled at a time using many wavelengths. While the chemical analysis of the stars was a cinch, the age was another matter. It was a difficult proposal.
It all started off with a set of stars that had been seen from the Kepler satellite which is in space. The lengthy duration of viewing led to the mass of the stars being discovered. And once the mass was known, finding out the age was easy enough.
Thus a model of the stars and their masses alongside their ages was built. This is a very important step since previously the ages of the stars were considered difficult to calculate.
Other methods of determining age include looking at a star through a telescope while it spins. But this is a long and laborious technique of observation.
Many stars in the map are red giants. This is a good starting point. According to one of the researchers: “These are an extremely valuable star to get ages for because they are very bright and we see them at very large distances.”
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The researcher also spoke of how “Our galaxy started out as a small disc and its grown from the inside out.”It was something which was expected by the experts. The rest of the information confirms all this.