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arXiv 2303.03232astro-ph.EP
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CO 存在与否？利用 SPIRou 收窄 WASP-127 b 大气的 CO 丰度约束并恢复 H₂O 探测结果

CO or no CO? Narrowing the CO abundance constraint and recovering the H2O detection in the atmosphere of WASP-127 b using SPIRou

Anne Boucher, David Lafrenière, Stefan Pelletier, Antoine Darveau-Bernier, Michael Radica, Romain Allart, Étienne Artigau, Neil J. Cook, Florian Debras, René Do… 展开作者

Anne Boucher, David Lafrenière, Stefan Pelletier, Antoine Darveau-Bernier, Michael Radica, Romain Allart, Étienne Artigau, Neil J. Cook, Florian Debras, René Doyon, Eric Gaidos, Björn Benneke, Charles Cadieux, Andres Carmona, Ryan Cloutier, Pía Cortés-Zuleta, Nicolas B. Cowan, Xavier Delfosse, Jean-François Donati, Pascal Fouqué, Thierry Forveille, Konstantin Grankin, Guillaume Hébrard, Jorge H. C. Martins, Eder Martioli, Adrien Masson, Sandrine Vinatier

备注：
23 pages, 13 figures, Submitted for publication in the Monthly Notice of the Royal Astronomical Society
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AI总结：

本研究利用高分辨率光谱仪SPIRou观测系外行星WASP-127 b，探测到H₂O与暂定的OH信号，联合多望远镜反演排除富CO情形，约束了CO₂等分子丰度与低C/O比非平衡化学情景，为研究该行星形成提供依据。

摘要：

精确测量行星大气中的化学丰度是约束系外行星形成历史的必要条件。近期一项针对 WASP-127b 的研究使用哈勃空间望远镜（HST）和斯皮策空间望远镜（Spitzer）开展观测，该行星是一颗近距离的蓬松亚土星，以4.2天的周期绕其类太阳宿主恒星运行，研究得到的透射光谱特征丰富，在4.5微米处存在强超额吸收。但这些仪器的光谱分辨率和覆盖范围有限，无法区分该信号是由CO还是CO₂吸收导致，低C/O比和高C/O比的情形都有可能。本文我们利用高分辨率光谱仪SPIRou对WASP-127 b开展近红外（0.9–2.5微米）凌星观测，目标是通过2.3微米的CO谱带区分CO与CO₂。借助SPIRou，我们以5.3σ的t检验显著性探测到了H₂O，并观测到一个与OH吸收相符的暂定（3σ）信号。通过SPIRou+HST+Spitzer的联合反演分析，我们给出CO丰度的上限为log₁₀[CO]<-4.0，排除了富CO的情形；同时估算得到log₁₀[CO₂]为-3.7^(+0.8)_(-0.6)，该丰度水平恰好能匹配4.5微米处观测到的超额吸收。我们还对其他主要的含碳、含氧、含氮分子设定了丰度约束，结果支持低C/O比（0.10^(+0.10)_(-0.06)）的非平衡化学情景。我们进一步讨论了这些结果在行星形成研究背景下的意义。未来还需要开展高分辨率和低分辨率的补充观测，以验证这些结果并深化我们对这颗独特行星的认识。

英文摘要：

Precise measurements of chemical abundances in planetary atmospheres are necessary to constrain the formation histories of exoplanets. A recent study of WASP-127b, a close-in puffy sub-Saturn orbiting its solar-type host star in 4.2 d, using HST and Spitzer revealed a feature-rich transmission spectrum with strong excess absorption at 4.5 um. However, the limited spectral resolution and coverage of these instruments could not distinguish between CO and/or CO2 absorption causing this signal, with both low and high C/O ratio scenarios being possible. Here we present near-infrared (0.9--2.5 um) transit observations of WASP-127 b using the high-resolution SPIRou spectrograph, with the goal to disentangle CO from CO2 through the 2.3 um CO band. With SPIRou, we detect H2O at a t-test significance of 5.3 sigma and observe a tentative (3 sigma) signal consistent with OH absorption. From a joint SPIRou + HST + Spitzer retrieval analysis, we rule out a CO-rich scenario by placing an upper limit on the CO abundance of log10[CO]<-4.0, and estimate a log10[CO2] of -3.7^(+0.8)_(-0.6), which is the level needed to match the excess absorption seen at 4.5um. We also set abundance constraints on other major C-, O-, and N-bearing molecules, with our results favoring low C/O (0.10^(+0.10)_(-0.06)), disequilibrium chemistry scenarios. We further discuss the implications of our results in the context of planet formation. Additional observations at high and low-resolution will be needed to confirm these results and better our understanding of this unusual world.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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