Astronomers Unfurl Star Migration in the Milky Way

Looking at 100,000 stars in the Milky Way, a scientific team discovered that these stars are migrating long distances from their birthplace.

The team not only created a map of star migration patterns in our galaxy, but were also able to deduct how and when the stars were born.

Making use of the Sloan Digital Sky Survey III (SDSS), an infrared spectrograph, the team unfurled the migration patterns and chemical composition of 30 percent of the stars in the Milky Way.

“This exercise can be described as galactic archaeology. These data reveal the locations, motions, and compositions of the stars, which provide insights into their formation and their history”,

commented SDSS III survey coordinator and scientific publications coordinator of the project, Donald Schneider.

Particularly, the scientists relied on the SDSS Apache Point Observatory Galactic Evolution Explorer or the APOGEE to look at the 100,000 stars over a four-year timeframe. The migration pattern was deducted from the chemical composition of the stars, which, according to the team, was the key factor in determining the history of each star and its ancestry.

The chemical composition of each star is determined as the light wavelengths beaming from these bodies are analyzed. Each spectral line represents a certain element or compound. As stars are born and die, their spectroscopic signatures are the key to determining the atmospheres’ chemical print and thus their timelines.

“Stellar spectra show us that the chemical makeup of our galaxy is constantly changing. 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”,

stated Jon Holtzman, NMSU astronomer involved in the study.

As such, each star generation in the Milky Way is proportionally richer in heavy chemical elements than the previous. At the same time, not all new star generation have the same amount of heavy elements.

The chemical print of each star generation varies greatly across the Milky Way. Yet, heavy elements are the key to understanding where the stars were born and how they migrated to other places in the galaxy.

Putting all data together, the research team created a model showing Milky Way stars migrating radially from the center of the galaxy. The migration patterns were also linked to the galactic disk’s irregularities in mass distribution.

As such, in the spiral arms of our galaxy, where mass is distributed unevenly, the inward and outward migration patterns were obvious.

The study features in the Astrophysical Journal.

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