NASA’s Hubble Uncovers Case of Missing Oxygen in Nearby Dwarf Galaxies

Researchers using NASA's Hubble Space Telescope studied nearly 40 nearby dwarf galaxies-small galaxies with a few thousand to hundreds of millions of stars-and found that much of the oxygen they expected to see is missing. Oxygen, a tracer of a wider set of heavy elements, is relatively easy to detect and measure, making it a reliable indicator of how chemical elements are distributed in a galaxy. The scientists studied oxygen to understand how it is distributed inside stars, in the gas between stars, and in the space between galaxies. Simulations predict that significantly more oxygen should reside in these galaxies, but that's not what they found.

Instead, the study revealed that dwarf galaxies can hold onto only a small fraction of the oxygen made by their stars. Energy from massive stars and galactic winds unleashed by supernovae are apparently more effective at removing oxygen from low-mass galaxies than current models predict. The findings will improve our understanding of how galaxies evolve over time, and why our universe looks the way it does today.