AI 中文总结
研究星斑不均匀性对直接成像行星光谱反演的影响，用ExoVista和BARBIE代码模拟，考虑太阳型及高活跃恒星活动，与静止恒星比较，量化影响，如特定情况下水检测信噪比提高、反照率反演准确性降低等。
AI 中文摘要
恒星活动是通过径向速度和凌日法探测及表征系外行星的主要复杂因素，即将到来的宜居世界天文台（HWO）促使人们考虑其对直接成像的影响。直接成像行星的光谱会因宿主恒星活动而变化，这种差异可能导致行星半径测量不准确及其与恒星对比度光谱出现意外的外部引起的变化。为评估HWO的科学能力和要求，量化这些影响的大小很重要。我们展示了使用ExoVista代码生成光谱和BARBIE代码进行光谱反演，对类地系外行星进行HWO式观测的模型反演结果，考虑了太阳型恒星活动和高活跃快速旋转体，并与理想化的静止宿主恒星进行比较。在静止情况下，检测0.9微米处的大气水汽需要信噪比约为5，0.74微米处约为13。我们发现对于太阳型活动，对反演的影响可忽略不计，但对于某些高活跃恒星在极限几何条件下可能存在问题。对于一个极端情况，即有一个10%覆盖面积的大斑点观测者不可见，水检测所需的信噪比在0.9微米处增加到约8，0.74微米处增加到约18，还会降低反演反照率的准确性，导致值约为真实值的2/3。根据这些结果，我们估计了恒星变异性和星斑对HWO式观测可能产生的影响。
英文摘要
Stellar activity is a major complication in the detection and characterization of exoplanets by both radial velocities and transits, and the upcoming Habitable Worlds Observatory (HWO) invites us to also consider its effect on direct imaging. Spectra of directly-imaged planets can vary with the activity of their host stars because the face of the star we see is not the same as the face reflected by the planet. This discrepancy could potentially result in inaccurate measurements of the planet's radius and unexpected, externally-caused variability in its contrast spectrum with the star. To assess the scientific capabilities and requirements of HWO, it is important that the magnitude of these effects be quantified. We present results of model retrievals of Earth-like exoplanets observed with an HWO-style survey, as they would appear when affected by starspots, using the ExoVista code for spectrum generation and the BARBIE code for spectroscopic retrieval. Both Solar-type stellar activity and highly active rapid rotators are considered and compared with an idealized quiescent host star. In the quiescent case, ${\rm SNR}\approx5$ is needed to detect atmospheric water vapor at 0.9 microns and ${\rm SNR}\approx13$ at 0.74 microns. We find that for Solar-type activity, the effect on retrievals will be negligible, but it could present problems for certain highly-active stars at limiting geometries. For an extreme case with a single large spot with 10\% coverage not visible to the observer, the SNR required for water detection increases to ${\rm SNR}\approx8$ at 0.9 microns and ${\rm SNR}\approx18$ at 0.74 microns. It also decreases the accuracy of the retrieved albedo, resulting in a value $\sim2/3$ of the true value. In light of these results, we estimate the impact that stellar variability and starspots may have on an HWO-style survey.
Comments20 pages, 5 figures, 3 tables, accepted to JATIS
