标题： ALMA Band 9观测揭示PDS 70盘中的泄漏尘埃陷阱 显示英文标题

标题： Leaky dust trap in the PDS 70 disk revealed by ALMA Band 9 observations

摘要： 我们使用阿塔卡马大型毫米/亚毫米波阵列（ALMA）在9号波段（671 GHz）以0.242$^{\prime\prime}$的分辨率获得了PDS 70盘的新观测结果，这些结果为盘中亚毫米颗粒的空间分布提供了有价值的见解。 数据揭示了一种环状形态，其径向峰值位于之前在红外波长和更长的毫米观测中所见的峰值之间。 此外，我们在9号波段检测到一个可能的外侧肩部，而在更长的波长下未观察到。 这些发现表明，由9号波段追踪的小颗粒（$\sim 100 \mu$m）可能既向内又向外逃逸出压力凸起，或者可能追踪的是与更长波长探测的不同盘层。 对盘在毫米波长的多波长分析以及对光谱能量分布的最佳拟合显示，在环状区域周围存在厘米级颗粒，该区域的尘埃表面密度也达到峰值，这与尘埃陷阱模型相容。 盘腔中的颗粒大小并未得到很好的约束，但与小至10$\mu$m的颗粒一致，支持了小尘埃颗粒通过腔体的假设。 我们使用尘埃演化模型证明，湍流粘度为$\alpha \gtrsim 10^{-3}$可使小颗粒通过盘间隙，而需要$\alpha \lesssim 5 \times 10^{-3}$来保持大颗粒在压力凸起中。 PDS 70的9号波段观测验证了理论模型，并确认了通过盘间隙的卵石通量的存在。 显示英文摘要

摘要： We present new observations of the PDS 70 disc obtained with the Atacama Large Millimeter/sub-millimeter Array (ALMA) in Band 9 (671 GHz) at 0.242$^{\prime\prime}$ resolution, which provide valuable insights into the spatial distribution of sub-millimetre grains in the disc. The data reveal a ring-like morphology, with a radial peak located between those previously observed at infrared wavelengths and longer millimetre observations. Additionally, we detect a tentative outer shoulder in Band 9 that is not observed at longer wavelengths. These findings suggest that small grains ($\sim 100 \mu$m) traced by Band 9 may be escaping from the pressure bump both radially inwards and outwards, or may be tracing different disc layers than those probed at longer wavelengths. A multi-wavelength analysis of the disc at millimetre wavelengths and the best fit to the spectral energy distribution shows the presence of centimetre grains around the ring location, where the dust surface density also peaks, compatible with dust trap models. The grain size in the disc cavity is not well constrained but is consistent with grains as small as 10 $\mu$m, supporting the hypothesis that small dust grain filters through the cavity. We use dust evolution models to demonstrate that a turbulent viscosity of $\alpha \gtrsim 10^{-3}$ allows small grains to filter through the disc gap, while $\alpha \lesssim 5 \times 10^{-3}$ is required to retain large grains in the pressure bump. The Band 9 observations of PDS 70 validate theoretical models and confirm the presence of pebble flux through the disc gap.