发表机构
INAF-Osservatorio Astronomico di Palermo; ESA/ESTEC Science Engagement and Oversight Office (SCI-E) Directorate of Science (SCI)（意大利国家天体物理研究所巴勒莫天文台; 欧洲空间局/欧洲空间研究与技术中心科学参与和监督办公室（SCI-E）科学司（SCI））
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究恒星变异对Ariel Tier 3重复观测的影响，提出三种缓解方法，发现逐步光学数据截断和逐次校正可有效减少反演偏差，确保活跃系统的大气表征可行。
AI 中文摘要
Ariel 的 Tier 3 观测策略为在光谱和时间域探索行星与恒星变异提供了独特机遇。然而，若缺乏合适的工具，宿主星的时域变异可能会使不同历元观测数据的联合分析复杂化。我们研究了恒星变异对 Ariel Tier 3 观测的影响，并建立了三种物理复杂度递增的缓解方法。通过对一个受不同黑子和光斑结构污染的理想系统进行模拟重复观测，我们比较了朴素未修改的叠加方法、通过逐步移除污染最严重的光学波长对红外区域进行单独分析，以及使用恒星-行星联合反演对单次访问进行校正。我们发现，在强恒星变异下，叠加不一致的访问会在反演的行星属性中产生显著偏差，尽管单一活动校正仍能较好地恢复行星参数。逐步进行光学数据截断可在一定程度上显著提高反演精度，而无需在反演中进行校正，且仅造成适度的精度损失。在叠加前对单次访问进行校正可产生更一致的光谱和通常更小的不确定性，但需要更大的计算开销。这些结果表明，在解释 Ariel 重复观测时应考虑恒星变异，但这并不妨碍对活跃系统的大气表征。一套灵活的缓解方法，辅以预备和同期恒星监测，可以针对单个目标调整恒星变异的处理方式，同时保持最大化 Ariel 科学回报所需的效率。
英文摘要
Ariel's Tier 3 observing strategy offers a unique opportunity to explore planetary and stellar variability in the spectral and time domain. However, without the correct toolkit, temporal variability of the host star may complicate combined analysesof observations obtained at different epochs. We investigate the impact of stellar variability on Ariel Tier 3 observations and establish three different mitigation approaches of increasing physical complexity. Using simulated repeated observations of a favourable system contaminated by different spot and facula configurations, we compare a naive, unmodified stacking approach, separate analysis of the infrared region through progressive removal of the most strongly contaminated optical wavelengths, and the correction of individual visits using combined star-planet retrievals. We find that stacking inconsistent visits can produce substantial biases in the retrieved planetary properties under strong stellar variability, although a single activity correction can still recover the planetary parameters reasonably well. Applying progressive optical data cuts substantially improves the accuracy of retrievals up to a point, without requiring any in-retrieval correction and causing only a modest loss of precision. Correcting individual visits prior to stacking produces more consistent spectra and generally smaller uncertainties, but requires greater computational effort. These results demonstrate that stellar variability should be considered when interpreting repeated Ariel observations, but need not preclude atmospheric characterisation of active systems. A flexible suite of mitigation approaches, supported by preparatory and contemporaneous stellar monitoring, can allow the treatment of stellar variability to be adapted to individual targets while maintaining the efficiency required to maximise Ariel's scientific return.
Comments16 pages (excluding Appendices), submitted to RASTI Ariel Special Issue
