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The Orion Molecular Cloud is the nearest massive-star forming region. Massivestars have profound effects on their environment due to their strong radiationfields and stellar winds. Velocity-resolved observations of the [CII]$158\,\mu\mathrm{m}$ fine-structure line allow us to study the kinematics ofUV-illuminated gas. Here, we present a square-degree-sized map of [CII]emission from the Orion Nebula complex obtained by the upGREAT instrumentonboard SOFIA, covering the entire Orion Nebula (M42) plus M43 and the nebulaeNGC 1973, 1975, and 1977. We compare the stellar characteristics of these threeregions with the kinematics of the expanding bubbles surrounding them. Thebubble blown by the O7V star $\theta^1$ Ori C in the Orion Nebula expandsrapidly, at $13\,\mathrm{km\,s^{-1}}$. Simple analytical models reproduce thecharacteristics of the hot interior gas and the neutral shell of thiswind-blown bubble and give us an estimate of the expansion time of$0.2\,\mathrm{Myr}$. M43 with the B0.5V star NU Ori also exhibits an expandingbubble structure, with an expansion velocity of $6\,\mathrm{km\,s^{-1}}$.Comparison with analytical models for the pressure-driven expansion of H\,{\scii} regions gives an age estimate of $0.02\,\mathrm{Myr}$. The bubblesurrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionisexpands at $1.5\,\mathrm{km\,s^{-1}}$, likely due to the over-pressurizedionized gas as in the case of M43. We derive an age of $0.4\,\mathrm{Myr}$ forthis structure. We conclude that the bubble of the Orion Nebula is driven bythe mechanical energy input by the strong stellar wind from $\theta^1$ Ori C,while the bubbles associated with M43 and NGC 1977 are caused by the thermalexpansion of the gas ionized by their central later-type massive stars.

Expanding bubbles in Orion A: [CII] observations of M42, M43, and NGC 1977