A Third of the Milky Way Galaxy's Stars Have Moved, New Map Reveals
It turns out that stars in our Milky Way galaxy have changed. A new map of the Milky Way reveals that nearly a third of the stars have dramatically changed their orbits.
"In our modern world, many people move far away from their birthplaces, sometimes halfway around the world," said Michael Hayden, lead author of the new study, in a news release. "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."
In order to create the new map, the researchers used the SDSS Apache Point Observatory Galactic Evolution Explorer (APOGEE) spectrograph in order to observe 100,000 stars during a four-year period. They measured the elements in the atmosphere of each star in order to get a better sense of its ancestry and life history. More specifically, they looked at the spectra, which are detailed measurements of how much light the star gives off at different wavelengths.
"Stellar spectra shows us that the chemical makeup of our galaxy is constantly changing," said Jon Holtzman, one of the researchers. "Stars create heavier elements int heir cores, and when the stars die, those heavier elements go back into the gas from which the next stars form."
What was interesting is that the researchesr found that up to 30 percent of the stars they looked at had compositions that indicated that they were formed in parts of the galaxy far from their current positions. This, in particular, shows how these stars move and evolve over time.
"These latest results take advantage of only a small fraction of the available APOGEE data," said Steven Majewski, principal investigator. "Once we unlock the full information content of APOGEE, we will understand the chemistry and shape of our galaxy much more clearly."
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