Original title: The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula
J. D. Soler, H. Beuther, S. C. O. Glover, R. S. Klessen +14 · September 2026
Big, heavy stars release huge amounts of energy, wind, and matter into space. These stellar winds blow massive bubbles into surrounding clouds of gas, but figuring out the true weight and structure of these giant bubbles is difficult. To study this, astronomers observed 21-centimeter emission signals from neutral atomic hydrogen in the nearby extended Orion nebula. By mapping this gas in high detail, they tracked how the bubble expands into its surroundings. They discovered that the expanding bubble's front hemisphere contains 100 solar massesA unit of mass equal to the mass of our Sun, used to describe astronomical objects. of material. This is roughly ten times less massive than earlier estimates based on ionized carbon, which suggests astronomers previously overestimated the mass of this nearby wind-blown bubble. However, hidden molecular hydrogen gas might also account for part of the difference. The team also uncovered new shapes around the nebula, including a likely secondary bubble and a straight protrusion sticking out roughly four parsecs.
Imagine you're cleaning out a closet and think it's packed full of clothes. You start pulling things out and realize it's only one-tenth as full as you believed because many items were hidden or misjudged. In this paper, astronomers measured the gas around a star-forming region and found it has far less mass than earlier methods indicated, which changes how we understand the energy from stars.
Astronomers studying how massive stars shape their surroundings now have to revise their estimates of gas mass in the Orion Nebula. This affects models of stellar feedback, which is crucial for understanding galaxy evolution and star formation across the universe.
The abstract does not rule out that molecular hydrogen could account for part of the mass difference, so the full reason for the discrepancy isn't explained.
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The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula — J. D. Soler, H. Beuther, S. C. O. Glover et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.