A group of researchers has created the largest map of the Milky Way galaxy, indicating how old the stars in our galaxy are. The project led by investigators from the Max Planck Institute for Astronomy, Heidelberg shows that the Milky Way is extending outward. Placed at ten thousands of light years away, the old stars are near the center and young ones are near the outskirts. The map was presented at the conference of the American Astronomical Society (AAS).
The team led by researcher Melissa Ness analyzed the light from the red starts using the SDSS (the Sloan Digital Key Survey), which with the help of multi-filter imaging and a spectroscope it enabled the scientists to measure certain parts of the sky.
According to Ness the placement of the starts in the galaxy are important because they allow the scientists to understand how the spiral galaxy was formed. The investigators analyzed the red starts because they believed that their age can be inferred from their composition and mass. Based on this assumption the team managed to discover that frequently older stars are close to the center of the Milky Way and younger stars have the tendency to form at the edge of the galaxy and they are 50.000 light-years away from the older stars.
Red giant stars have a low mass in spite of their dimension; they are bright dying stars and according to Dr. Ness they are very important when one wants to measure ages because they are very luminous and easy to observe from a distance. The researched team looked at the light coming from approximately 70.000 red giant stars.
In order to determine the ages of the stars the research team combined what they knew about wavelength with notations about the same starts coming from NASA’s Kepler satellite. Since the satellite was launched into space in 2009 it has discovered over 1.000 stars.
The life course of starts is important in the relationship between the mass and the age of red giant stars. While some stars die in a violent explosion called supernova, some stars do not have enough mass to produce such an intense event.
With the help of the galaxy’s age map, the researchers discovered how the Milky Way has evolved throughout billions of years, namely that the galaxy was firstly populated by older stars which helped with the formation of the new disk where younger generations of stars are now.
Image Source: noao.edu