Hubble Finds Dwarf Galaxies Lose Most of Their Oxygen to Space

Hubble Space Telescope observations of 37 nearby dwarf galaxies reveal that most of the oxygen produced by their stars has been expelled from the galaxies. The study, published in The Astrophysical Journal, used archival Hubble optical images together with data from the retired Spitzer Space Telescope, the Very Large Array, and the Australian Telescope Compact Array to map oxygen in stars, gas, and dust. Simulations had predicted that dwarf galaxies should retain a larger share of their heavy elements, but the findings show that supernova‑driven winds remove oxygen more efficiently than current models allow. The missing oxygen likely travels into the circumgalactic and intergalactic medium, altering the chemical makeup of the space between galaxies. The results will refine models of galaxy evolution and guide future observations with the Roman and James Webb Space Telescopes.