Some of us like to use the expression ‘as old as the universe’ when talking about something ancient, that’s been there since the beginning of time. But galaxies are generally pretty old as well. Not as old as the universe, but definitely older than your nosy next door neighbor. Wanting to find out our galaxy’s age, scientists reveal Milky Way growth pattern.
- The scientists used two telescopes in the study, the Sloan Digital Sky Survey and the Kepler satellite
- The findings were presented last week at the 227th meeting of the American Astronomical Society
- The model was determined by using the galaxy’s stars’ ages and spectra
- There are other techniques to measure a star’s age, but they are much more time consuming
- All of the stars presented on the model are red giants
For the first time in history, although it was suspected before, we know for sure the exact manner in which our galaxy started and continued its growth – from the inside out.
The Milky Way’s age map, as the scientists refer to it, was put together using data from two very important telescopes – the Kepler satellite and Sloan Digital Sky Survey’s Apogee project.
The latter was used to look at thousands of stars with a wide array of wavelengths; this process was done with 300 stars at a time. It revealed the stars’ spectra, which was of great use to the astronomers in working out the chemical composition of the stars.
Meanwhile, the former was used how it is generally used, by having it pointed at a few stars at a time, for a long time, and eventually determining their mass. A star’s mass is what researchers generally use to determine the star’s age.
Having both the chemical composition of the stars, as well as their age, the team developed the map, which correlated a star’s color spectrum to its age and mass. Then they used those findings to calculate the ages of all the remaining red giant stars in the galaxy based on just their spectra.
The only reason the researchers could do what they did was because of the new technology, otherwise it would have taken way too long to determine the stars’ spectra. The reason why the scientists used red dwarves in their measurements was because they are the brightest, and can be seen over very large distances.
Concluding the paper, the researchers stated that our galaxy started out as a very small disk, and eventually grew outward until it became what it currently is today.
Image source: mpia.de