One-third of Milky Way stars have changed orbits

This data and additional chemical information include the amount of light emissions measured at various wavelengths where specific elements and compounds are shown via linear visualizations for astronomers to read and predict the composition of the stars.

Evidence of stellar migration had previously been seen in stars near the Sun, but the new study is the first clear evidence that migration occurs throughout the galaxy, the researchers noted.

‘In our modern world, many people move far away from their birthplaces, sometimes halfway around the world, ‘ said Michael Hayden of New Mexico State University (NMSU), the lead author of the new study. Researchers say that their discovery brings to the forefront a new understanding of how stars are formed, and how they travel throughout our galaxy. Stars in essence possess heavier elements within their cores and when a star dies, these elements are now transformed into gas that can produce a new generation of stars. “Now we’re finding the same is true of stars in our galaxy”. The stars appear to move randomly toward and away from the Galactic center, radically in some cases. The stars have moved around far from where they started.

By measuring the elements in each star’s atmosphere, the team was able to interpret the newly drawn-out map of the Milky Way.

The Sloan Digital Sky Survey-III (SDSS), which uses the 2.5-meter wide-angle optical telescope at Apache Point Observatory in New Mexico, was used to allow astronomers to spot the chemical elements that make up a star using spectroscopy, and then they were able to figure out where these stars began based on areas of the galaxy that are known to contain large quantities of those elements, according to a Discovery News report. Spectra show prominent lines that correspond to elements and molecules present.

Astronomers can tell how old a star is by examining its spectroscopic signature, much like counting the rings on a tree to determine its age. They tied the trace presence of these elements in certain regions of the Milky Way to the places throughout the galaxy where they are found in abundance.

“These latest results take advantage of only a small fraction of the available APOGEE data”, said Majewski, the principal investigator of APOGEE.

However, star formation is not always the same for each star, which can be different depending on the region of the galaxy where some regions are more dynamic or turbulent from the others.

According to Bird, the APOGEE project is transforming the relatively new field of “galactic archeology” that uses fossil records of stars throughout the galaxy to reconstructthe history of the Milky Way.

As a result, “the APOGEE survey gives us the opportunity to piece together the formation history of the entire galaxy”, Bird said. These “in and out” movements could explain irregularities observed in the galactic disc, such as the iconic spiral arms of the Milky Way. “APOGEE’s main mission is to collect these fossils from all over the galaxy”, said Jonathan Bird, a post-doctoral fellow in the Vanderbilt Initiative in Data-intensive Astrophysics, who was heavily involved in the study.