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The Earliest Galaxy Walked Across the Sky
A red JWST source once proposed as a galaxy at redshift 32 moved against its background, identifying it instead as a cold Milky Way brown dwarf.
Summary
A red JWST source once proposed as a galaxy at redshift 32 moved against its background, identifying it instead as a cold Milky Way brown dwarf.
Researchers compared new JWST medium-band imaging with discovery observations separated by about 3.5 years and measured Capotauro moving 132 plus or minus 20 milliarcseconds relative to 68 compact reference sources. That motion rules out an extragalactic object at more than six sigma, according to the preprint. Template fitting instead favors a roughly 350-kelvin Y-type brown dwarf about 730 parsecs away. The result shows why multi-epoch imaging matters when unresolved cool stars imitate extreme early-galaxy colors; it remains an author-reported preprint submitted to MNRAS.
Why it matters
A red JWST source once proposed as a galaxy at redshift 32 moved against its background, identifying it instead as a cold Milky Way brown dwarf.
Limits and context
- That motion rules out an extragalactic object at more than six sigma, according to the preprint.
Key claims
A red JWST source once proposed as a galaxy at redshift 32 moved against its background, identifying it instead as a cold Milky Way brown dwarf.
Qualification: That motion rules out an extragalactic object at more than six sigma, according to the preprint.
Evidence: source-2026-08-10-001
Sources
- arXiv preprint 2608.07461arXiv · primary research
Corrections
No corrections have been recorded for this story.