Researchers using NASA's Hubble Space Telescope studied 37 nearby dwarf galaxies and found that much of the oxygen expected from their stars is missing, according to a paper published Monday in The Astrophysical Journal. Simulations predict significantly more oxygen should remain in these galaxies, which contain a few thousand to hundreds of millions of stars.

In the Galaxies Losing Oxygen via Winds (GLOW) project, funded by NASA and the National Science Foundation, scientists traced oxygen across stars, gas between stars, and space between galaxies. Co-investigator Grace Telford of the University of Utah said the oxygen must have been ejected, requiring energy from massive stars and supernova explosions to drive material out of the host galaxies.

The study indicates galactic winds from supernovae remove oxygen from low-mass galaxies more effectively than current models predict, leaving dwarf galaxies able to hold onto only a small fraction of the oxygen their stars make. The team combined archival Hubble optical imaging with data from the retired Spitzer Space Telescope and the ground-based Very Large Array and Australian Telescope Compact Array. Principal investigator Kristen Wingfield McQuinn said oxygen is relatively easy to detect and measure, making it a reliable indicator of how elements are distributed in a galaxy.