Characterizing Exoplanetary Atmospheres at High Resolution with SPIRou: Detection of Water on HD 189733 b
Characterizing Exoplanetary Atmospheres at High Resolution with SPIRou: Detection of Water on HD 189733 b
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DOI：
10.3847/1538-3881/ac1f8e
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发表时间：
2021-08
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通讯作者：
A. Boucher;A. Darveau-Bernier;S. Pelletier;D. Lafreniére;É. Artigau;N. Cook;R. Allart;M. Radica;R. Doyon;B. Benneke;L. Arnold;X. Bonfils;V. Bourrier;R. Cloutier;J. Gomes da Silva;E. Deibert;X. Delfosse;J. Donati;D. Ehrenreich;P. Figueira;T. Forveille;P. Fouqu'e;Jonathan Gagn'e;E. Gaidos;G. H'ebrard;R. Jayawardhana;B. Klein;C. Lovis;J. Martins;E. Martioli;C. Moutou;N. Santos
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作者：
A. Boucher;A. Darveau-Bernier;S. Pelletier;D. Lafreniére;É. Artigau;N. Cook;R. Allart;M. Radica;R. Doyon;B. Benneke;L. Arnold;X. Bonfils;V. Bourrier;R. Cloutier;J. Gomes da Silva;E. Deibert;X. Delfosse;J. Donati;D. Ehrenreich;P. Figueira;T. Forveille;P. Fouqu'e;Jonathan Gagn'e;E. Gaidos;G. H'ebrard;R. Jayawardhana;B. Klein;C. Lovis;J. Martins;E. Martioli;C. Moutou;N. Santos
我们展示了第一个系外行星大气探测，作为SPIRou遗产调查的一部分，这是一个300晚的大型观测计划，利用了SPIRou的能力，SPIRou是安装在加拿大-法国-夏威夷望远镜（3.6米）上的新型近红外高分辨率（R ~ 70,000）分光偏振计。我们观测到HD 189733b的两次凌日，HD 189733b是一颗被广泛研究的热木星，在其透射光谱中显示出明显的水蒸气吸收。当结合两次凌日时，我们成功地探测到行星的水蒸气吸收量为5.9σ，使用交叉相关t检验，或使用对数似然计算ΔBIC > 10。利用贝叶斯检索框架，假设参数化温度-压力（T-P）剖面大气模式，我们将透射光谱探测区域的行星大气参数约束为以下值：log10VMR[H2O] =−4.4−0.4+0.4，P云< 0.2 bar（灰色云），这两个值都与先前对该行星的研究一致。我们的回收水体积混合比略低于太阳能；尽管，将它与先前从其他研究中检索到的超级太阳CO丰度结合起来，将意味着超级太阳C/O比。我们进一步测量到行星信号的净蓝移为- 4.62 - 0.44+0.46 km s - 1，这比以前的许多测量值要大一些，不太可能仅仅是由行星大气中的风造成的，尽管它可能是由行星尾翼主导的凌日信号来解释的。这种巨大的蓝移在所有不同的检测/检索方法中都被观察到，并且在两次凌日中都是独立的。
We present the first exoplanet atmospheric detection made as part of the SPIRou Legacy Survey, a Large Observing Program of 300 nights exploiting the capabilities of SPIRou, the new near-infrared high-resolution (R ∼ 70,000) spectropolarimeter installed on the Canada–France–Hawaii Telescope (3.6 m). We observed two transits of HD 189733b, an extensively studied hot Jupiter that is known to show prominent water vapor absorption in its transmission spectrum. When combining the two transits, we successfully detect the planet’s water vapor absorption at 5.9σ using a cross-correlation t-test, or with a ΔBIC > 10 using a log-likelihood calculation. Using a Bayesian retrieval framework assuming parameterized temperature–pressure (T-P) profile atmospheric models, we constrain the planet atmospheric parameters, in the region probed by our transmission spectrum, to the following values: log10VMR[H2O] = −4.4−0.4+0.4 , and P cloud ≳ 0.2 bar (gray clouds), both of which are consistent with previous studies of this planet. Our retrieved water volume-mixing ratio is slightly subsolar; although, combining it with the previously retrieved super-solar CO abundances from other studies would imply a super-solar C/O ratio. We furthermore measure a net blueshift of the planet signal of −4.62−0.44+0.46 km s−1, which is somewhat larger than many previous measurements and unlikely to result solely from winds in the planet's atmosphere, although it could possibly be explained by a transit signal dominated by the trailing limb of the planet. This large blueshift is observed in all of the different detection/retrieval methods that were performed and in each of the two transits independently.