Astronomers Find 3rd Dark-Matter-Free Galaxy, Linking DF9 to 100-Million-Sun System
Updated
Updated · Maui Now · Jun 16
Astronomers Find 3rd Dark-Matter-Free Galaxy, Linking DF9 to 100-Million-Sun System
3 articles · Updated · Maui Now · Jun 16
Summary
DF9 has emerged as the third known galaxy apparently lacking dark matter, with Keck Observatory measurements placing its mass at about 100 million Suns—fully explained by visible matter alone.
KCWI observations of stellar motions showed DF9 is far lighter than a normal galaxy of its type; with typical dark matter, astronomers said it should be roughly 100 times more massive.
DF9 also sits in the same narrow linear structure as the earlier oddities DF2 and DF4, strengthening the case that all three formed in a single violent, high-speed galactic collision.
That scenario suggests ordinary gas was stripped from its surrounding dark matter and later formed galaxies on its own, offering fresh evidence that dark matter acts as a physical substance rather than a gravity effect.
The Yale-led study, published in The Astrophysical Journal, points future observations toward searching for leftover gas from the collision and refining how such galaxies form.
If a cosmic collision created these 'pure' galaxies, where is the missing dark matter now hiding?
How does finding a galaxy with no dark matter provide the strongest proof that dark matter is real?
The Third Dark Matter-Free Galaxy: How DF9 Challenges Our Understanding of the Universe
Overview
In June 2026, astronomers announced the discovery of NGC 1052-DF9 (DF9), the third known galaxy found to be largely devoid of dark matter. This finding, led by Yale University and published in The Astrophysical Journal, adds to the puzzling cases of DF2 and DF4. Together, these galaxies challenge the long-held belief that galaxies form only within dark matter halos. Instead, their existence suggests that stars and even entire galaxies can form outside these invisible structures, especially under extreme cosmic conditions. This discovery has major implications for our understanding of how galaxies form and evolve.