A NEW APPROACH TO ANALYZING HST SPATIAL SCANS: THE TRANSMISSION SPECTRUM OF HD 209458 b
A NEW APPROACH TO ANALYZING HST SPATIAL SCANS: THE TRANSMISSION SPECTRUM OF HD 209458 b
复制标题
分析 HST 空间扫描的新方法：HD 209458 b 的传输频谱
DOI：
--
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
G. Tinetti
中科院分区：
文献类型：
--
作者：
A. Tsiaras;I. Waldmann;M. Rocchetto;R. Varley;G. Morello;M. Damiano;M. Damiano;G. Tinetti
哈勃太空望远镜上的广视场3号相机是目前使用最广泛的观测行星外大气的仪器之一，特别是使用了空间扫描技术。越来越多的系外行星被使用这一技术进行研究，因为它能够在不使灵敏探测器饱和的情况下观察明亮的目标。在这项工作中，我们提出了一种新的管道来分析空间扫描技术获得的数据，从仪器提供的原始数据开始。除了常用的校正技术外，我们还考虑了仪器的几何失真，当它们与扫描过程结合时，其影响可能变得重要。我们的方法可以提高现有数据的光度精度，还可以扩展空间扫描技术的限制，因为它允许分析更长的空间扫描。作为我们方法和流水线的应用，我们给出了对HD 209458 b的空间扫描渡越光谱的重新分析的结果，我们计算了每个波长通道的渡越深度，平均相对不确定度为40ppm。我们用我们的全贝叶斯光谱反演代码-REX来解释最终的光谱，它确认了HD 209458 b的大气中存在水蒸气和云。狭窄的波长范围限制了我们解开拟合的大气参数之间的简并的能力。为了解决这个问题，需要在更广泛的光谱范围内提供更多的数据。
The Wide Field Camera 3 on the Hubble Space Telescope is currently one of the most widely used instruments for observing exoplanetary atmospheres, especially with the use of the spatial scanning technique. An increasing number of exoplanets have been studied using this technique as it enables the observation of bright targets without saturating the sensitive detectors. In this work, we present a new pipeline for analyzing the data obtained with the spatial scanning technique, starting from the raw data provided by the instrument. In addition to commonly used correction techniques, we take into account the geometric distortions of the instrument, the impact of which may become important when they are combined with the scanning process. Our approach can improve the photometric precision for existing data and also extend the limits of the spatial scanning technique, as it allows the analysis of even longer spatial scans. As an application of our method and pipeline, we present the results from a reanalysis of the spatially scanned transit spectrum of HD 209458 b. We calculate the transit depth per wavelength channel with an average relative uncertainty of 40 ppm. We interpret the final spectrum with -REx, our fully Bayesian spectral retrieval code, which confirms the presence of water vapor and clouds in the atmosphere of HD 209458 b. The narrow wavelength range limits our ability to disentangle the degeneracies between the fitted atmospheric parameters. Additional data over a broader spectral range are needed to address this issue.