A recent study led by Chikako Yasui, an Assistant Professor at the National Astronomical Observatory of Japan, sheds light on star formation in the outskirts of the Milky Way galaxy. This region, known as Sh 2-209 or S209, offers a unique glimpse into the conditions of the early universe.
Using the powerful Subaru Telescope, the research team observed S209 and made an intriguing discovery. They identified two star clusters within S209, one large and one small, comprising a total of around 1,500 member stars. This marks the first time such a large-scale star-forming cluster has been found in the outer part of our galaxy.
What’s particularly fascinating about S209 is its chemical composition. Compared to the solar neighborhood, S209 contains a higher concentration of pure hydrogen and fewer heavier elements. This makes it an excellent analog for studying the prevailing conditions that existed approximately 10 billion years ago in the universe.
By examining the distribution of stellar masses within S209, the team aimed to determine if the local environment significantly affects the mass distribution of stars. The results indicate that the distribution of stellar masses in S209 is not dramatically different from what is observed near the solar system. In other words, the clusters in S209 exhibit similar mass distributions to those found in our vicinity.
This finding is crucial for our understanding of star formation. Most stars form within clusters alongside stars of varying masses. While previous studies hinted at similar mass distributions in nearby clusters, it was unclear if this held true on a broader scale or if it was merely a result of local conditions.
“The outer part of the Milky Way has properties akin to those of the early universe,” says Yasui. “Our findings suggest that although a considerable number of massive stars were formed in the early universe, their abundance does not differ significantly from typical star clusters in the present era.”
Published in The Astrophysical Journal on February 2, 2023, the study titled “Mass Function of a Young Cluster in a Low-metallicity Environment. Sh 2-209” provides valuable insights into the effects of the local environment on star formation and the distribution of stellar masses.
Source: Subaru Telescope