Hubble survey probes 29 low-metallicity massive stars

The University of Utah-led TEMPOS project used Hubble's Cosmic Origins Spectrograph to study 29 massive stars in six dwarf galaxies with metallicity below one-fifth of the Sun's. For stars below about 10% solar metallicity, stellar wind speeds drop far more sharply than higher-metallicity trends predict, helping explain the odd early galaxies seen by Webb.

• 29 massive stars studied across six dwarf galaxies below one-fifth solar metallicity
• Observing a single star can take up to 35 hours of Hubble time
• Wind speeds plunge sharply below about 10% solar metallicity
• Results published Sept. 21, 2026, in The Astrophysical Journal Supplement Series