Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 μm

By J. Birkby, Remco J. de Kok, M. Brogi, E. Mooij, H. Schwarz, S. Albrecht, I. Snellen. 2013

256 citations recorded by the source corpus.

We report a 4.8{$σ$} detection of water absorption features in the day side spectrum of the hot Jupiter HD 189733 b. We used high-resolution (R {\tilde} 100 000) spectra taken at 3.2 {$μ$}m with CRIRES on the VLT to trace the radial-velocity shift of the water features in the planet's day side atmosphere during 5 h of its 2.2 d orbit as it approached secondary eclipse. Despite considerable telluric contamination in this wavelength regime, we detect the signal within our uncertainties at the expected combination of systemic velocity (V\_sys=-3\^{}$\{$+5$\}$\_$\{$-6$\}$ km s$^{-1}$) and planet orbital velocity (K\_p=154\^{}$\{$+14$\}$\_$\{$-10$\}$ km s$^{-1}$), and determine a H$_{2}$O line contrast ratio of (1.3 {\plusmn} 0.2) {\times} 10$^{-3}$ with respect to the stellar continuum. We find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although we do note a marginal increase in the significance of our detection to 5.1{$σ$} with the inclusion of carbon dioxide in our template spectrum. This result demonstrates that ground-based, high-resolution spectroscopy is suited to finding not just simple molecules like CO, but also to more complex molecules like H$_{2}$O even in highly telluric contaminated regions of the Earth's transmission spectrum. It is a powerful tool that can be used for conducting an immediate census of the carbon- and oxygen-bearing molecules in the atmospheres of giant planets, and will potentially allow the formation and migration history of these planets to be constrained by the measurement of their atmospheric C/O ratios.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/69813712b9fe7ac7d9a5444a5be899a147dd7e34

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Line
5. D. Deming
6. J. D'esert
7. Sara Seager
8. M. Marley

In Instrumentation

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Line
5. D. Deming
6. J. D'esert
7. Sara Seager
8. Laura Kreidberg

Citations in the corpus

• A PRECISE WATER ABUNDANCE MEASUREMENT FOR THE HOT JUPITER WASP-43b (2014, background): “Detections of water have been reported for a number of giant exoplanets (Grillmair et al. 2008; Konopacky et al. 2013; Deming et al. 2013; Birkby et al. 2013), and some previous measurements have yielded precise constraints on the abundance of water in these objects (Lee et al. 2013; Line et al.…”
• WATER VAPOR IN THE SPECTRUM OF THE EXTRASOLAR PLANET HD 189733b. I. THE TRANSIT (2014, methodology): “Grillmair et al. (2008) attributed to water a 10µm absorption feature in the emission spectrum of HD 189733b, and recently, Birkby et al. (2013) have done so at 3.2µm using phase curves rather than observations at secondary eclipse.”
• Extremely Irradiated Hot Jupiters: Non-oxide Inversions, H− Opacity, and Thermal Dissociation of Molecules (2018, methodology): “…resolution by spectroscopically separating the planet’s flux contribution from its host star and telluric lines in a way very similar to techniques used to detect spectroscopic binary stars (e.g., Snellen et al. 2008; Birkby et al. 2013; de Kok et al. 2013; Brogi et al. 2014; Schwarz et al. 2015).”
• Transmission spectral properties of clouds for hot Jupiter exoplanets (2014, background): “…of HD 189733b in the infrared hint at the presence of molecular absorption by water in the planet’s upper atmosphere with additional evidence from both high resolution spectroscopy and eclipse spectral data (Grillmair et al. 2008; Birkby et al. 2013; Pont et al. 2013; McCullough et al. 2014).”
• ROTATION AND WINDS OF EXOPLANET HD 189733 b MEASURED WITH HIGH-DISPERSION TRANSMISSION SPECTROSCOPY (2015, methodology): “The absence of CO 2 signal was also observed in past dayside, 3.2-µm observations (Birkby et al. 2013).”
• Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b (2014, methodology): “Furthermore, we determined the statistical significance of the signal as in previous work (Brogi et al. 2012, 2013; de Kok et al. Article number, page 7 of 10 A&A proofs: manuscript no. hd179_final 2013b; Birkby et al. 2013).”
• Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph (2015, background): “Several spectrographs will be built soon to conduct investigations in the infrared, such as SPIROU, CARMENES, IRD and CRIRES+. Judging from recent results (e.g., Birkby et al. 2013; Snellen et al. 2014), a strong development of atmospheric detections and characterization in the infrared is possible.”
• ExoMol molecular line lists XXX: a complete high-accuracy line list for water (2018, background): “Some of these exoplanet observations require high accuracy laboratory data (Birkby et al. 2013; Brogi et al. 2014).”
• Combining high-dispersion spectroscopy with high contrast imaging : Probing rocky planets around our nearest neighbors (2015, methodology): “Birkby et al. (2013) reached a 1σ H2O line contrast of <3×10−4 in 5 hours of observations at 3.2µm for HD189733 b (K=5.54) using the same instrument.”