论文标题
使用hco $^+$同位素作为原动性磁盘间隙中气体耗竭的示踪剂
Using HCO$^+$ isotopologues as tracers of gas depletion in protoplanetary disk gaps
论文作者
论文摘要
在原月经磁盘的尘埃连续体中看到的广泛的环和间隙有时会伴随分子线发射中看到的相似子结构。一个例子是AS 209中的100 au的外部差距，这表明H $ _ {13} $ co $^+$和C $ _ {18} $ o发射强度随间隙中的连续体而降低，而DCO $^+$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $在间隙内部增加。 我们的目的是研究DCO $^+$/H $ _ {13} $ CO $^+$和DCO $^+$/hco $^+$ $^+$ $ $^+$ $ $^+$ $ $^+$ $比率在两种情况下：假设气体耗竭遵循尘埃耗竭，只有灰尘耗尽，灰尘只耗尽了。 我们首先使用热化学模型Andes对物理磁盘结构进行了建模。这个1+1D稳态磁盘模型计算气体和灰尘的热平衡，包括FUV，X射线，宇宙射线和其他电离源，以及减少的分子冷却剂化学网络。之后，采用了这种物理结构，用于计算具有氘分馏的扩展气体化学网络的分子丰度。使用石灰产生理想的合成光谱和0矩图。 我们能够定性地重现DCO $^+$强度的增加，以及H $ _ {13} $ CO $^+$和C $ _ {18} $ o磁盘间隙内的强度的减小，该磁盘间隙内的强度与在质量上相似，这与Outer of the Outer as the Outer As 209 Gap的差异在定性上相似。相应的磁盘模型假设气体和尘埃都在间隙中耗尽。只有灰尘耗尽的气体含量丰富的型号的模型在所有HCO $^+$ iSotopologues和c $ _ {18} $ o中都会产生太亮的发射。 DCO $^+$/h $ _ {13} $ CO $^+$线比可用于探测CO雪线外尘埃连续间隙中的气体耗竭。 dco $^+$/c $ _ {18} $ o线比显示出相似的，尽管较弱，效果；但是，可以与单个Alma或Noema设置同时观察这些物种。
The widespread rings and gaps seen in the dust continuum in protoplanetary disks are sometimes accompanied by similar substructures seen in molecular line emission. One example is the outer gap at 100 au in AS 209, which shows that the H$_{13}$CO$^+$ and C$_{18}$O emission intensities decrease along with the continuum in the gap, while the DCO$^+$ emission increases inside the gap. We aim to study the behavior of DCO$^+$/H$_{13}$CO$^+$ and DCO$^+$/HCO$^+$ ratios in protoplanetary disk gaps assuming the two scenarios: the gas depletion follows the dust depletion and only the dust is depleted. We first modeled the physical disk structure using the thermo-chemical model ANDES. This 1+1D steady-state disk model calculates the thermal balance of gas and dust and includes the FUV, X-rays, cosmic rays, and other ionization sources together with the reduced chemical network for molecular coolants. Afterward, this physical structure was adopted for calculations of molecular abundances with the extended gas-grain chemical network with deuterium fractionation. Ideal synthetic spectra and 0th-moment maps were produced with LIME. We are able to qualitatively reproduce the increase in the DCO$^+$ intensity and the decrease in the H$_{13}$CO$^+$ and C$_{18}$O intensities inside the disk gap, which is qualitatively similar to what is observed in the outer AS 209 gap. The corresponding disk model assumes that both the gas and dust are depleted in the gap. The model with the gas-rich gap, where only the dust is depleted, produces emission that is too bright in all HCO$^+$ isotopologues and C$_{18}$O. The DCO$^+$/H$_{13}$CO$^+$ line ratio can be used to probe gas depletion in dust continuum gaps outside of the CO snow line. The DCO$^+$/C$_{18}$O line ratio shows a similar, albeit weaker, effect; however, these species can be observed simultaneously with a single ALMA or NOEMA setup.
