A Rare Extragalactic Stellar Stream Reveals Hidden Dark Matter

A rare stellar stream, observed in the ultra-diffuse galaxy UGC 9050-Dw1, reveals a previously unknown structure that provides insights into dark matter distribution. The stream, a thin, curved band of stars, was detected despite the galaxy's sparse star population, making it visible against a dark background. The discovery offers a new method to measure dark matter in distant galaxies, as the stars in the stream follow nearly the same orbit, allowing scientists to estimate the galaxy's total mass.

• The stellar stream's formation is similar to structures seen in the Milky Way, where the galaxy's rotation strips stars into streams.
• The discovery highlights the unique ability of the ultra-diffuse galaxy to reveal such structures due to its sparse star population.
• The study used the stellar stream to measure dark matter, confirming results consistent with previous methods and demonstrating the effectiveness of this technique beyond the Milky Way.

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