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Bringing the Visible Universe into Focus with Robo-AO
Published on: February 12, 2013
Identifying the principal mechanism of star formation feedback
Chong Li1, Rouyu Li2,3, Keping Qiu4,5
1Purple Mountain Observatory and Key Laboratory of Radio Astronomy, CAS, Nanjing 210033, China.
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 HI 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 HI 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 HI-to-H2 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.
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