Stars in our own Milky Way are far from being static celestial bodies, researchers argue. They migrate from their place of birth as they grow and eventually die.
Researchers peered throughout our galaxy and observed 100,000 stars, which due to their chemical composition, as well as that of their atmospheres revealed that they were born in different locations of the Milky Way and travelled to their current position.
The key tool that enabled the research team to analyze the stars is the Sloan Digital Sky Survey III or the SDSS III, with the SDSS Apache Point Observatory Galactic Evolution Explorer or the APOGEE.
SDSS III is a highly performant spectrograph that helped the research team discern not only stars migration patterns, but also the time and place of birth of the 100,000 stars under observation for a period of four years.
“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”,
stated the survey coordinator of SDSS III and scientific publications coordinator, Donald Schneider.
This process of ‘galactic archeology’ drew greatly on data retrieved from the spectrograph. The spectrographic signature of each star holds a wealth of information on the location and time it was born, as well as its migration pattern.
As the SDSS III analyzes the chemical print of each star, based on the wavelengths of each spectra, it can detect precisely which elements or compounds go into its making. Thus, ancestry is established.
“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.
Despite this fact, new stars across the Milky Way do not all have the same chemical composition. As they migrate, mature and die, some regions are infused with heavy elements, while some are not as densely populated by the heavy gases.
The migration pattern also contributes to the uneven distribution of the heavy elements. The Milky Way, with its irregular distribution of mass throughout the galactic disk drives the stars to wander from a clearly established migration path, thus creating an inward-outward pattern.
The resulting blend of new and old stars is fascinating. Yet, a full understanding of our own galaxy is still a long time in front, the researchers believe.
Nonetheless, the SDSS III team put together their findings to create a computer model that shows how the stars are migrating radially from and to the center of the Milky Way.
The study can be found the Astrophysical Journal.
Photo Credits: astro.wisc.edu