标题： 硅酸盐日晕：探究行星观测中颗粒方向性的影响 显示英文标题

标题： Silicate Sundogs: Probing the Effects of Grain Directionality in Exoplanet Observations

摘要： 晶体冰在地球大气中由于取向依赖的衰减可以产生壮观的现象，如日狗和晕，为作用在气溶胶颗粒上的外部过程提供诊断信息。 晶体矿物气溶胶，如石英（SiO$_2$）和斜方辉石/橄榄石（MgSiO$_3$/Mg$_2$SiO$_4$），长期以来被认为会在热木星大气中形成，JWST MIRI LRS已观测证实了晶体石英的存在。 由于热木星大气中存在强烈的水平风（$\sim$1 - 5 km s$^{-1}$）和细小的气溶胶颗粒（$<1$ $\mu$ m），我们表明气溶胶可能与风发生机械对齐。 我们随后推导了石英、斜方辉石和橄榄石的方向依赖光学特性，并假设随机和机械对齐取向建模透射和发射光谱，发现所有三种晶体气溶胶的取向可以在观测光谱中产生$\geq$100 ppm 的差异（8 - 12$\mu$m）。 我们在JWST MIRI LRS的透射和发射数据上运行反演，发现方向性本身无法物理解释透射数据，这指向多形或实验室数据不足，并在发射数据中发现方向性的弱提示（1.0 - 1.3$\sigma$）。 这项工作展示了JWST MIRI LRS在未来观测中检测气溶胶方向性的能力，以及一种探测气溶胶如何与大气动力过程相互作用的技术。 为了促进系外行星数据中气溶胶的探索，开源代码POSEIDON已更新（v1.3.1），包括144种新的方向性和温度气溶胶，其光学性质已预先计算，并新增了气溶胶模型。 显示英文摘要

摘要： Crystalline ice in Earth's atmosphere can produce spectacular phenomena due to orientation-dependent attenuation, such as sun dogs and halos, providing diagnostics of the external processes acting on the aerosol grains. Crystalline mineral aerosols, such as quartz (SiO$_2$) and enstatite/forsterite (MgSiO$_3$/Mg$_2$SiO$_4$), have long been predicted to form in hot Jupiter atmospheres with JWST MIRI LRS verifying the existence of crystalline quartz observationally. Due to the strong horizontal winds ($\sim$ 1 - 5 km s$^{-1}$) and small aerosol grains ($<1$ $\mu$m) found in hot Jupiter atmospheres, we show that aerosols could be mechanically aligned with the winds. We then derive directional-dependent optical properties of quartz, enstatite, and forsterite and model transmission and emission spectra assuming random and mechanically aligned orientations, finding that the orientation of all three crystalline aerosols can impart $\geq$ 100 ppm differences in observed spectra (8 - 12 $\mu$m). We run retrievals on JWST MIRI LRS transmission and emission data of WASP-17b and find that directionality alone cannot physically explain the transmission data, pointing towards polymorphs or insufficient lab data, and find weak hints of directionality (1.0 - 1.3$\sigma$) in the emission data. This work demonstrates the power of JWST MIRI LRS in detecting aerosol directionality with future observations, and a technique by which to probe how aerosols interact with atmospheric dynamical processes. To foster the exploration of aerosols in exoplanet data, the open-source code POSEIDON has been updated (v1.3.1) to include 144 new directional and temperature aerosols with precomputed optical properties, alongside new aerosol models.