ANCHORAGE, AK, 2025-06-15 06:30:00
Astronomers have made a surprising discovery: the rate at which massive stars form near the center of our Milky Way galaxy is lower than expected. This goes against the assumption that the Galactic Center, with its dense clouds of gas and dust, would be a hotbed of star formation.
Stellar Slowdown
New research reveals that star formation in the Galactic Center is surprisingly slow, despite the presence of abundant star-forming material.
- Massive star formation in the Galactic Center is slower than in other parts of the galaxy.
- Extreme conditions, including interactions with a central black hole, may be the cause.
- One region, Sgr B2, appears to be an exception, retaining its star-forming potential.
The study, led by Dr. James De Buizer at the SETI Institute and Dr. Wanggi Lim at IPAC at Caltech, focused on three star-forming regions: Sgr B1, Sgr B2, and Sgr C. The team used observations from NASA’s now-retired SOFIA airborne observatory. Their findings suggest that the extreme environment near the Galactic Center is hindering the birth of massive stars, which is the study’s primary focus.
“Recent studies have concluded that star formation is likely depressed near the Galactic Center, and even that there may be no present star formation occurring there,” said De Buizer. “Since presently-forming massive stars are brightest at long infrared wavelengths, we obtained the highest resolution infrared images of our Galaxy’s central-most star-forming regions. The data show that, contrarily, massive stars are presently forming there, but confirm at a relatively low rate.”
The Galactic Center’s Challenges
The Galactic Center, despite its abundance of star-forming material, seems to be a challenging environment for massive star formation. The team compared these regions to others further out in the galaxy and confirmed the slower rate. The extreme conditions, including the swift orbit around the black hole at the galaxy’s center and interactions with older stars, are believed to be the culprits.
These conditions may prevent gas clouds from clumping together to form stars in the first place. They could also stop the stars that do form from staying together long enough for continued star formation. Unlike typical star-forming regions, the areas studied may only produce one generation of stars.
However, Sgr B2 stands out. While its present rate of massive star formation is low, it seems to have retained its dense gas and dust, hinting at a possible future star cluster. Traditionally, giant H II regions, like Sgr B1 and Sgr C, have been viewed as hosts of massive star clusters. However, this study challenges that view, suggesting they might represent a new type of stellar nursery.
Infrared Vision
SOFIA’s ability to see through the obscuring gas and dust allowed the team to identify over six dozen massive stars forming in the Galactic Center regions. However, these regions still formed fewer stars and topped out at a lower mass compared to the galactic average. “These Galactic Center star-forming regions are in many ways very similar to the massive star-forming regions in the relatively calm backwaters of our galaxy,” said Lim. “However, the most massive stars we are finding in these Galactic Center regions, though still remarkably large, fall short in both size and quantity compared to those found in similar regions elsewhere in our Galaxy.”
“Furthermore, such star-forming regions typically hang on to large reservoirs of star-forming material and continue to produce multiple epochs of stars, but that appears to not be the case for these Galactic Center regions.”
Lim will present the study’s results at the 246th meeting of the American Astronomical Society in Anchorage, AK.
