2024ApJ...969..113T

We study the kinematics of a pillar, namely G287.76-0.87, using three rotational lines of ¹²CO(5-4), ¹²CO(8-7), ¹²CO(11-10), and a fine structure line of [O I] 63 μm in southern Carina observed by SOFIA/GREAT. This pillar is irradiated by the associated massive star cluster Trumpler 16, which includes η Carina. Our analysis shows that the relative velocity of the pillar with respect to this ionization source is small, ∼1 km s^–1, and the gas motion in the tail is more turbulent than in the head. We also performed analytical calculations to estimate the gas column density in local thermal equilibrium (LTE) conditions, which yields N_CO as (∼0.2-5) × 10¹⁷ cm^–2. We further constrain the gas's physical properties in non-LTE conditions using RADEX. The non-LTE estimations result in ${n}_{{{\rm{H}}}_{2}}\simeq {10}^{5}\,{\mathrm{cm}}^{-3}$ and N_CO ≃ 10¹⁶ cm^–2. We found that the thermal pressure within the G287.76-0.87 pillar is sufficiently high to make it stable for the surrounding hot gas and radiation feedback if the winds are not active. While they are active, stellar winds from the clustered stars sculpt the surrounding molecular cloud into pillars within the giant bubble around η Carina.