An astronomer from the Liverpool John Moores University (LJMU) Astrophysics Research Institute has found a new group of stars within our Milky Way Galaxy. The implications of this discovery could be enormous, as this sheds light on the early stages of the formation of the Milky Way Galaxy.
More specifically, the discovery of the new star family provides a better understanding of the origins of globular clusters.
Globular clusters are specific areas comprised of approximately a million stars that appeared at the very beginning of the Milky Way Galaxy’s formation. These dense clusters orbit the center of the galaxy they belong to and are considered satellites, celestial bodies that orbit around a gravitational center. The Milky Way in particular has approximately 150 known globular clusters.
LJMU is one of many international institutions part of the Sloan Digital Sky Survey. This group has made many advances including the detection of clustering in galaxies, the discovery of the most distant quasars and brown dwarfs, the detection of kinematical and chemical populations of the Galactic bulge and the mapping of star streams.
One of the many projects of the program is the Apache Point Observatory Galactic Evolution Experiment (APOGEE). The goal of this project is to assemble infrared data of certain Milky Way stars.
The APOGEE project uses high-resolution, high signal-to-noise infrared spectroscopy to peer beyond the dust that obscures significant fractions of the Milky Way.
In doing so, the project hopes to survey over 100,000 red giant stars across all four regions of the Milky Way: the bulge, bar, disk and halo. Data collected, such as the radial velocities and chemical composition (also known as “chemical fingerprinting”), will provide entirely new understandings regarding the structure and formation of the Milky Way Galaxy.
“The center of the Milky Way is poorly understood, because it is blocked from view by intervening dust. Observing in the infrared, which is less absorbed by dust than visible light, APOGEE can see the center of the Galaxy better than other teams” Ricardo Schiavon, the lead researcher on the project, said in a press release.
It was through the infrared observation of the core of the Milky Way Galaxy that the new stars were unearthed. Groups of stars similar to the ones found in the novel family had only been observed inside globular clusters before.
However, the APOGEE project enabled the astronomers to, for the first time, discover and visualize stars from this population that seem to be outside of their original cluster.
It is possible that the unique star family may have belonged to globular clusters that were lost during the very violent beginnings of the Milky Way Galaxy core’s formation. If this proves to be correct, there would have been about 10 times as many globular clusters in the Milky Way when it first formed, compared to the number of clusters we observe currently.
Furthermore, if this hypothesis proves true about the newly discovered family of stars, it is likely that a large percentage of stars residing in the inner, core parts of the Milky Way belonged to and formed in globular clusters that were destroyed due to the violent nature of the Galaxy’s formation.
“This is a very exciting finding that helps us address fascinating questions such as what is the nature of the stars in the inner regions of the Milky Way, how globular clusters formed and what role they played in the formation of the early Milky Way — and by extension the formation of other galaxies,” Schiavon said.
