The ionizing radiation of massive stars sculpts the surrounding neutral gas into pillar-like structures. Direct signatures of star formation through outflows and jets are observed in these structures, typically at their tips. Recent numerical simulations have suggested that this star formation could potentially be triggered by photoionising radiation, driving compressive modes of turbulence in the pillars. In this study we use recent high-resolution ALMA observations of $^{12}\mathrm{CO}$, $^{13}\mathrm{CO}$, and $\mathrm{C}^{18} \mathrm{O}, \; J = 2-1$ emission to test this hypothesis for pillars in the Carina Nebula. We analyse column density and intensity-weighted velocity maps, and subtract any large-scale bulk motions in the plane of the sky to isolate the turbulent motions. We then reconstruct the dominant turbulence driving mode in the pillars, by computing the turbulence driving parameter $b$, characterised by the relation $\sigma_{\rho/\rho_0} = b \mathcal{M}$ between the standard deviation of the density contrast $\sigma_{\rho/\rho_0}$ (with gas density $\rho$ and its average $\rho_0$) and the turbulent Mach number $\mathcal{M}$. We find values of \mbox{$b\sim0.7$--$1.0$} for most of the pillars, suggesting that predominantly compressive modes of turbulence are driven in the pillars by the ionising radiation from nearby massive stars. We find that this range of $b$ values can produce star formation rates in the pillars that are a factor $\sim 3$ greater than with $b \sim 0.5$, a typical average value of $b$ for spiral-arm molecular clouds. Our results provide further evidence for the potential triggering of star formation in pillars through compressive turbulent motions.

中文翻译：

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关于由船底座星云柱中的电离反馈驱动的湍流的压缩性质

大质量恒星的电离辐射将周围的中性气体雕刻成柱状结构。在这些结构中观察到恒星形成的直接特征，通常是在它们的尖端。最近的数值模拟表明，这种恒星形成可能是由光电离辐射触发的，从而驱动了柱子中湍流的压缩模式。在这项研究中，我们使用 $^{12}\mathrm{CO}$、$^{13}\mathrm{CO}$ 和 $\mathrm{C}^{18} \mathrm{ 的最新高分辨率 ALMA 观测O},\; J = 2-1$ 发射来检验船底座星云中的支柱的这一假设。我们分析柱密度和强度加权速度图，并减去天空平面中的任何大规模整体运动以隔离湍流运动。然后，我们通过计算湍流驱动参数 $b$ 重建支柱中的主导湍流驱动模式，其特征在于 $\sigma_{\rho/\rho_0} = b \mathcal{M}$密度对比 $\sigma_{\rho/\rho_0}$（气体密度 $\rho$ 及其平均值 $\rho_0$）和湍流马赫数 $\mathcal{M}$。我们发现大多数支柱的 \mbox{$b\sim0.7$--$1.0$} 值，表明主要是压缩湍流模式是由附近大质量恒星的电离辐射在支柱中驱动的。我们发现这个 $b$ 值范围可以在柱子中产生比 $b\sim 0.5$ 大一个因子 $\sim 3$ 的恒星形成率，这是螺旋臂分子的典型平均值 $b$云。