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How do stellar winds create bubbles inside H II regions?

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H II region Centre of the Orion Nebula (M42). Astronomers have identified some 700 young stars in this 2.5-light-year-wide area. They have also detected over 150 protoplanetary disks, or proplyds, which are believed to be embryonic solar systems that will eventually form planets. These stars and proplyds generate most of the nebula's light. This picture is a mosaic combining 45 images taken by the Hubble Space Telescope.

In an H II region, stellar winds from massive, hot stars create large cavities or bubbles by pushing against the denser, cooler gas that originally surrounded the star.1

The process occurs as follows:

Wind Generation: Exciting stars within the H II region generate extremely fast outflows of gas from their atmospheres, known as stellar winds.1
Energy Conversion: As the stellar wind flows radially outward, it passes through a transition zone where its kinetic energy is converted into heat.1
Bubble Formation: This resulting hot, tenuous gas fills the majority of the cavity—often 90 percent or more—effectively carving out a bubble within the surrounding, comparatively dense H II region.1

These bubbles serve to separate the luminous filaments of the warmer, denser gas found within the nebula. Over time, the massive stars responsible for these winds may eventually explode as supernovae, which further disturbs and reshapes the surrounding interstellar gas.1