H$_2$O 发射作为卵石漂移的示踪：输运与热化学模型耦合的见解
H$_2$O emission as tracer of pebble drift: insights from coupling transport and thermochemical models
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中文总结 AI 辅助
本研究耦合输运与热化学模型，探究冷H$_2$O发射作为卵石漂移示踪的可靠性，发现尘埃输送可增强发射，而1500/6000 K谱线比值受温度与尘埃分布影响，不能准确追踪卵石通量。
中文摘要 AI 辅助
（删节版）原行星盘内部区域的组成已知会因冰粒的输送而随时间变化。JWST-MIRI 观测到的冷 H$_2$O 发射常被假设为这种卵石漂移的示踪。然而，尚不清楚光解离或尘埃共同输送等过程在多大程度上会阻碍此类探测。我们旨在获得盘中输运的改进的二维视图，以更好地理解这些过程如何被 JWST-MIRI 所见的 H$_2$O 发射示踪。我们将一维输运代码 DiscEvolution 与二维热化学代码 DALI 相结合，创建了多个模型网格，其中气相丰度、尘埃性质或两者根据输运模型而变化。我们考虑了 H$_2$O 雪线内有无交通堵塞的情景。气体和尘埃的输运都会导致盘内温度的显著变化，这强烈影响谱线通量和比值。当存在交通堵塞时，由于尘埃的共同输送，H$_2$O 的输送可能不被注意。此外，冷 H$_2$O 谱线的相对强度被发现对此气相 H$_2$O 的输送不敏感。相反，当存在交通堵塞时，仅将尘埃输送到内部盘即可大大增强冷 H$_2$O 谱线，并且可以仅通过输送尘埃而非 H$_2$O 来产生具有强冷 H$_2$O 发射的光谱。最近的工作使用 1500/6000 K H$_2$O 谱线比值作为确定穿过 H$_2$O 雪线的卵石质量通量的代理，但我们发现该谱线比值对盘的温度和尘埃分布相当敏感，并且通常不仅受冷 H$_2$O 质量的影响，还受热 H$_2$O 质量的影响。这引入了随时间变化的复杂性和趋势，与卵石通量的真实演化不符。
英文摘要
(Abridged) The composition of the inner regions of protoplanetary disks is known to change with time due to the delivery of icy grains. Cold H$_2$O emission seen with JWST-MIRI is often hypothesized to be a tracer of this pebble drift. However, it is unclear to what extent processes such as photodissociation or the co-delivery of dust may impede such detections. We aim to obtain an improved, 2D view of transport in disks, to better understand how these processes can be traced by H$_2$O emission as seen with JWST-MIRI. We combine the 1D transport code DiscEvolution with the 2D thermochemical code DALI to create several grids of models in which the gas-phase abundances, dust properties, or both are varied according to the transport model. We consider scenarios with and without a traffic jam inside the H$_2$O snowline. The transport of both gas and dust leads to significant temperature changes within the disk, which strongly influence line fluxes and ratios. When a traffic jam is present, the delivery of H$_2$O can proceed unnoticed due to the co-delivery of dust. In addition, the relative strength of cold H$_2$O lines is not found to be sensitive to this delivery of gas-phase H$_2$O. Instead, the cold H$_2$O lines can be greatly enhanced by the delivery of only dust to the inner disk when a traffic jam is present, and one can create a spectrum with strong cold H$_2$O emission solely through the delivery of dust rather than H$_2$O. Recent work has used the 1500/6000 K H$_2$O line ratio as a proxy to determine the pebble mass flux crossing the H$_2$O snowline, but we find that this line ratio is rather sensitive to the temperature and dust distribution of the disk, and is often influenced not only by the cold H$_2$O mass, but also by the hot H$_2$O mass. This introduces complexities and trends as a function of time that do not match the true evolution of the pebble flux.
发表机构
- Leiden University（莱顿大学）
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