Plate Nº 52 · recorded November 2, 2026
Space & AstronomyReported finding
Hubble Finds Dwarf Galaxies Are Losing Most of Their Oxygen
Hubble observations of 37 nearby dwarf galaxies show supernova winds blow away most of the oxygen their stars produce, exceeding what simulations predict.
By Elena Vasquez4 min read770 words
In brief
- The study examined 37 nearby dwarf galaxies and was published Monday in The Astrophysical Journal.
- Dwarf galaxies retain only a small fraction of the oxygen their stars produce.
- GLOW was funded by NASA and the National Science Foundation.
- A 2014 study previously found Milky Way-like galaxies lose much of their oxygen to circumgalactic haloes.
- Hubble has operated for over three decades as a NASA-ESA project.
By Elena Vasquez
A study of 37 nearby dwarf galaxies published Monday in The Astrophysical Journal found that much of the oxygen those galaxies should contain is simply gone. NASA's Hubble Space Telescope did the looking. The verdict: dwarf galaxies hold onto only a small fraction of the oxygen their stars make.
The team calls the project GLOW — Galaxies Losing Oxygen via Winds. It was funded by NASA and the National Science Foundation.
Where did the oxygen go?
Computer simulations predict that significantly more oxygen, which serves as a tracer for a wider set of heavy elements, should reside inside these small galaxies. It doesn't. So the researchers conclude the oxygen left.
"Oxygen is produced by stars, which are inside of galaxies. We know that the oxygen had to be inside of the galaxies at some point in the past, so the oxygen must have been ejected," said co-investigator Grace Telford, assistant professor in the Department of Physics and Astronomy at the University of Utah. "And to do that, you need energy from massive stars and supernova explosions to drive material out of the host galaxies and into the space between galaxies."
In plain terms: galactic winds from supernova explosions strip oxygen out of low-mass galaxies far more effectively than current models predict.
Why track oxygen of all elements?
Practicality, mostly. Oxygen is the most abundant element after hydrogen and helium. It's relatively easy to detect and measure, and scientists understand well how stars produce it.
"So, it's really for practical reasons that we've chosen oxygen," said Kristen Wingfield McQuinn, GLOW principal investigator. She heads the Science Operations Center for NASA's newly launched Nancy Grace Roman Space Telescope at the Space Telescope Science Institute in Baltimore and is an associate professor at Rutgers University in New Brunswick, New Jersey.
"Oxygen is one of the primary elements formed by stars. Being able to trace how much oxygen gets made, and then how much is distributed inside and outside of galaxies, helps us understand galaxy evolution," McQuinn said. "It also helps us learn where and how much galaxies are enriching the space between galaxies, called the intergalactic medium."
How the study worked
The team used archival optical imaging from Hubble to resolve individual stars and work out each galaxy's star-formation history and chemical composition. They added data from NASA's retired Spitzer Space Telescope plus two ground-based radio arrays, the Very Large Array and the Australian Telescope Compact Array.
The 37 targets were chosen for two reasons:
- Their masses fall in the range where theory predicts supernovae will expel increasing amounts of oxygen.
- They're close enough for Hubble to pick out individual stars — something impossible for the vast majority of known dwarf galaxies, which sit too far away.
One of the galaxies, NGC 4449, appears in a new Hubble image released with the study: a clumpy, irregular cloud speckled with bright blue points of light and pink patches.
What's still unknown?
Astronomers already suspected galaxies expel a lot of oxygen and other heavy elements. The open question is where the material ends up. A 2014 study of Milky Way-like, star-forming galaxies found they lost a large fraction of their oxygen, with some of it sitting in diffuse gas haloes around galaxy disks — the circumgalactic medium.
GLOW extended that work to low-mass galaxies across a wide range of masses and environments. Previous teams have measured oxygen in the circumgalactic medium of dwarfs, but it remains unclear whether most of the missing oxygen sits there or has been flung completely beyond the galaxies' surroundings. That question stays open.
What comes next
McQuinn wants to study even lower-mass galaxies in the nearby universe. She has an approved program to use the Roman Space Telescope to find these faint, tiny systems across a wide swath of sky, then follow up with Hubble and NASA's James Webb Space Telescope for deeper views of their stars. The goal: reconstruct how they formed stars across cosmic time.
Telford's next step is using Hubble to zoom in on the individual massive stars that make oxygen and eject it, drawing on GLOW targets to characterize how those stars differ in small galaxies.
Hubble, a joint project of NASA and ESA, has operated for more than three decades. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope; the Space Telescope Science Institute in Baltimore conducts its science operations.
The takeaway: small galaxies make oxygen and then lose most of it, and supernova-driven winds are stronger than the models assumed.
via doi.org (Original)
More from Elena Vasquez
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Correspondent covering money, funding and market shifts around general science news at SciBeat.
288 articles
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