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Yale Astronomers Spot Dark-Matter-Free Dwarf DF9

6/18/2026

Summary

Story summary

U.S. astronomers at Yale announced that dwarf galaxy NGC 1052-DF9, 67 million light-years distant, lacks dark matter.
Using Keck’s Cosmic Web Imager, the team measured DF9’s total mass at 100 million solar masses.
Michael Keim reported that DF9 aligns with eight other galaxies, including DF2 and DF4.
Lead researcher Pieter van Dokkum suggested a collision stripped dark matter from gas, prompting the gas to form DF9 and its neighboring line galaxies.

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Story summary

U.S. astronomers at Yale announced that dwarf galaxy NGC 1052-DF9, 67 million light-years distant, lacks dark matter.
Using Keck’s Cosmic Web Imager, the team measured DF9’s total mass at 100 million solar masses.
Michael Keim reported that DF9 aligns with eight other galaxies, including DF2 and DF4.
Lead researcher Pieter van Dokkum suggested a collision stripped dark matter from gas, prompting the gas to form DF9 and its neighboring line galaxies.