Scientists have created a new map of the Milky Way, and it reveals the first-ever evidence of migrating stars.
The recent study determined 30 percent of stars have traveled across the galaxy, a finding that could reveal how stars are formed and how these stellar journeys occur, Pennsylvania State University reported.
"We were able to measure the properties of nearly 70,000 stars in our galaxy for this particular study using the innovative SDSS infrared spectrograph," said Donald Schneider, Distinguished Professor of Astronomy and Astrophysics at Penn State and a coauthor of the study. "This exercise can be described as galactic archeology. These data reveal the locations, motions, and compositions of the stars, which provide insights into their formation and their history."
To create this stunning map, the researchers used the SDSS Apache Point Observatory Galactic Evolution Explorer (APOGEE) spectrograph to look at over 10,000 stars in the Sloan Digital Sky Survey-III (SDSS).
"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. "Now we're finding the same is true of stars in our galaxy. About 30 percent of the stars in our galaxy have traveled a long way from where they were born."
The key to interpreting the map is measuring the elements in the atmosphere of each star. These elements are determined by the amount of light the stars give off at different wavelengths.
"Stellar spectra show us that the chemical makeup of our galaxy is constantly changing," said Jon Holtzman, an astronomer at NMSU who was involved in the study. "Stars create heavier elements in their cores, and when the stars die, those heavier elements go back into the gas from which the next stars form."
The APOGEE data allowed the researchers to map the relative amounts of 15 different elements including carbon, silicon, and iron. They were surprised to find up to 30 percent of stars had compositions suggesting they were formed in regions of the galaxy far from where they were found. They determined this phenomenon could be explained with a model that showed stars migrating radially, moving closer or farther from the galactic center throughout time. These "in and out" movements could explain irregularities observed in the galactic disc, such as the iconic spiral arms of the Milky Way.
"These latest results take advantage of only a small fraction of the available APOGEE data," said Steven Majewski, the Principal Investigator of APOGEE. "Once we unlock the full information content of APOGEE, we will understand the chemistry and shape of our galaxy much more clearly.
