Hubble study finds dwarf galaxies keep only a tenth of the oxygen their stars made

By the Everything Space news desk · 02 Nov 2026 · written from the sources below

Image: Phys.org

The findings suggest galactic winds purge heavy elements more efficiently than current simulations predict, reshaping views of how small galaxies evolve.

Astronomers analyzing archival Hubble Space Telescope data have found that 37 nearby dwarf galaxies hold onto only a small fraction of the oxygen their stars are calculated to have produced over time. On average, the galaxies retained about 11 percent of that oxygen, with individual galaxies ranging from 4 to 25 percent.

The research, led by a team including a Rutgers astrophysicist, is part of the Galaxies Losing Oxygen via Winds project, which tracks how much oxygen stars generate, how much stays within a galaxy, and how much is expelled into surrounding space. Oxygen was chosen as a tracer because it is abundant and emits light at wavelengths that are straightforward to detect and measure, making it a practical stand-in for other elements forged by stars.

The missing oxygen appears to have been carried away by galactic winds, outflows of gas pushed out by the energy released from massive stars and supernova explosions. According to the researchers, the scale of oxygen loss observed in these galaxies exceeds what current computer simulations predict, suggesting that these outflows are more effective at removing material than existing models account for.

To reach these conclusions, the team used Hubble imagery capable of resolving individual stars within each galaxy, since all 37 systems are close enough for that level of detail. By studying the stars' brightness and color, researchers reconstructed each galaxy's star-formation history and chemical evolution. They supplemented this with data from the retired Spitzer Space Telescope and ground-based radio observatories to estimate both the oxygen produced and the amount remaining.

The work builds on earlier research into larger, Milky Way-like galaxies, which found that much of their oxygen had escaped into the surrounding circumgalactic medium. The new study extends that line of inquiry to smaller galaxies across a range of masses and environments, though it remains unclear whether the oxygen lingers near these dwarf galaxies or travels much farther into intergalactic space.

Researchers involved in the project say future observations, including planned use of the Nancy Grace Roman Space Telescope, Hubble, and the James Webb Space Telescope, could help identify even smaller galaxies and examine the massive stars responsible for driving oxygen out of their hosts. Such work is aimed at better understanding how galaxies evolve and how they enrich the vast spaces between them with the elements that stars produce.

Written in Everything Space’s own words by our news-desk model from the sources above, and checked against them in code: every number in this report appears in its sources, and no sentence is copied from them.