PDS 70外盘偏振散射光的时间与颜色变化
Temporal and chromatic variation of polarized scattered light in the outer disk of PDS 70
AI总结：
本研究通过多波长、多历元偏振成像观测PDS 70外盘，发现其偏振反射率与亮度分布存在时间变化，并揭示波长依赖的远近侧对比，表明内盘阴影与表面几何影响显著。
摘要：
PDS 70是一个独特的系统，因为它拥有一个包含两颗已确认形成中行星的原行星盘，使其成为表征此类盘中尘埃的理想目标。我们展示了使用SPHERE/ZIMPOL上的$N_R$滤光片对PDS 70进行的新高对比度偏振差分成像，并结合了存档的VLT/SPHERE数据，涵盖五个波长（$N_R$、$VBB$、$J$、$H$和$Ks$），跨越八年间的七个观测历元。对于每个历元，我们校正了仪器分辨率引起的模糊效应，分析了方位角亮度分布，并推导了内禀的盘积分偏振反射率和亮度对比度。我们的分析揭示了积分偏振反射率和方位角亮度分布均存在显著的时间变化，表明来自未分辨内盘结构的可变阴影作用于外盘。尽管如此，我们观察到倾斜盘的近侧和远侧之间存在系统的波长依赖对比度，强调在数据解释中需要考虑内盘阴影和反射盘表面几何形状的影响。
英文摘要：
PDS 70 is a unique system as it hosts a protoplanetary disk with two confirmed forming planets, making it an ideal target for characterizing dust in such disks. We present new high-contrast polarimetric differential imaging of PDS 70 using the $N\_R$ filter on SPHERE/ZIMPOL, combined with archival VLT/SPHERE data across five wavelengths ($N\_R$, $VBB$, $J$, $H$, and $Ks$) spanning seven epochs over eight years. For each epoch, we corrected smearing effects from instrument resolution, analyzed azimuthal brightness profiles, and derived intrinsic disk-integrated polarized reflectivity and brightness contrasts. Our analysis reveals significant temporal variability in both integrated polarized reflectivity and azimuthal brightness profiles, suggesting variable shadowing on the outer disk from unresolved inner disk structures. Nonetheless, we observe a systematic wavelength-dependent contrast between the near and far sides of the inclined disk, highlighting the need to consider shadowing from the inner disk and surface geometry of the reflecting disk in data interpretation.
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