Identifying the principal mechanism of star formation feedback.

Li, Chong; Li, Rouyu; Qiu, Keping; Krco, Marko; Li, Di; Wang, Hongchi; Lyu, Xin; Duan, Yan et al. · Sci Adv · 2026

basic_science · Level V

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Abstract

Feedback from massive stars regulates the formation of next-generation stars and planets and thus shapes the evolution of galaxies, yet observational evidence capable of determining which mechanism dominates the feedback process has long been lacking. Here, we present a large-scale H<sub>I</sub> survey toward Orion A. With an unprecedented sensitivity and superior resolution, FAST (Five-hundred-meter Aperture Spherical radio Telescope) reveals a well-defined heart-shaped expanding H<sub>I</sub> bubble, enshrouding the well-known "Veil" bubble of ionized gas. The photoionization-driven and wind-driven gas expands at 10.9 and 13.8 kilometers per second, respectively, with a kinetic energy ratio of 1:2 assuming a spherical symmetry and a uniform H<sub>I</sub>-to-H<sub>2</sub> ratio. This first direct comparison within a single bubble shows that radiation does not dominate the feedback process as predicted by classical theories; instead, stellar winds contribute a comparable share of the injected kinetic energy.