Scientists have made the space growth pattern of the Milky Way galaxy thanks to innovative mixing of data collected as a result of the ongoing project, the Sloan Digital Celestial Survey, and a new method for determining the age of stars.
"As expected, the analysis shows that the central disk of the galaxy is formed from old red giants, which reach 13 billion years old, and young stars about 1 billion years old closer to the edge of the disk," said astronomer Melissa Ness of the Max Planck Institute of Astronomy. in Heidelberg, Germany.
"What we are able to do is to understand in detail how our galaxy was formed, looking at the age dispersion, age gradient and how the stars age depends on the height of the disk plane," Ness added.
Unique to this type of research is the method of dating, based on the dependence of the age of stars on their size. Ness and her colleagues used high-quality Sloan spectrum analysis, which compares the chemical composition of stars with optical data collected by the NASA Kepler space telescope to develop a model that can be used to accurately determine the age of stars. "This is a revolutionary decision, as it was very difficult to calculate the age of the stars based on their spectrum earlier. It is difficult, but important," Ness said.
The key was the discovered relationship between the age of the star and its carbon-nitrogen ratio, the concentration of which can be determined based on an analysis of the spectra of the star.
"The old red giants have the highest carbon-nitrogen ratio, and the young stars, on the contrary, have the lowest ratio," Ness said.
Working with samples of 2000 stars, scientists studied how the ratio varies with the mass of the star. They then included the results in a computer model and used it to calculate the mass and age of all the 70,000 red giants observed by the Apache Point Observatory.