Investigating the Relative Gas and Small Dust Grain Surface Heights in Protoplanetary Disks
Investigating the Relative Gas and Small Dust Grain Surface Heights in Protoplanetary Disks
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DOI：
10.3847/1538-4357/abf92e
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发表时间：
2021-04
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通讯作者：
Evan A. Rich;R. Teague;J. Monnier;C. Davies;A. Bosman;T. Harries;N. Calvet;F. Adams;D. Wilner;Zhaohuan Zhu
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作者：
Evan A. Rich;R. Teague;J. Monnier;C. Davies;A. Bosman;T. Harries;N. Calvet;F. Adams;D. Wilner;Zhaohuan Zhu
从细小的尘埃颗粒到鹅卵石的原行星盘中的尘埃演化是行星形成过程的关键。原行星盘中的气体会影响小尘埃颗粒(∼1μm)在盘中的垂直分布。利用记录的近红外偏振光和毫米波观测，我们测量了IMLUP、HD 163296和HD 97048(CU Cha)三个原行星盘的小尘埃粒子散射面和12Co气体发射面的尺度高度和耀斑参数β。对于IM LUP和HD 163296两个系统，12Co气体和小半径尘埃粒子的高度相似，但在较大半径(>；100Au)时，尘埃粒子散射面高度低于12Co气体发射面高度。在HD 97048的情况下，小的尘埃颗粒散射面在所有半径上都与12Co气体发射面的高度相似。我们运行了一个具有环面的一般原行星盘的原行星盘辐射传输模型，结果表明，观测到的散射面与12Co发射面没有差别。我们还对系统进行了分析建模，发现气尘比大于100时可以解释观测到的IM LUP和HD 163296的差异。这是对观测到的原行星盘中气体和小尘埃颗粒高度分布的首次直接比较。未来需要对气体发射和近红外散射光仪器进行观测，以在其他原行星盘中寻找类似的趋势。
Dust evolution in protoplanetary disks from small dust grains to pebbles is key to the planet formation process. The gas in protoplanetary disks should influence the vertical distribution of small dust grains (∼1 μm) in the disk. Utilizing archival near-infrared polarized light and millimeter observations, we can measure the scale height and flare parameter β of the small dust grain scattering surface and 12CO gas emission surface for three protoplanetary disks: IM Lup, HD 163296, and HD 97048 (CU Cha). For two systems, IM Lup and HD 163296, the 12CO gas and small dust grains at small radii from the star have similar heights, but at larger radii (>100 au), the dust grain scattering surface height is lower than the 12CO gas emission surface height. In the case of HD 97048, the small dust grain scattering surface has similar heights to the 12CO gas emission surface at all radii. We ran a protoplanetary disk radiative transfer model of a generic protoplanetary disk with TORUS and showed that there is no difference between the observed scattering surface and 12CO emission surface. We also performed analytical modeling of the system and found that gas-to-dust ratios larger than 100 could explain the observed difference in IM Lup and HD 163296. This is the first direct comparison of observations of gas and small dust grain height distribution in protoplanetary disks. Future observations of gas emission and near-infrared scattered-light instruments are needed to look for similar trends in other protoplanetary disks.