Strong water absorption in the dayside emission spectrum of the planet HD 189733b

By C. Grillmair, Adam Burrows, D. Charbonneau, Lee Armus, J. Stauffer, V. Meadows, J. Cleve, K. von Braun, D. Levine. 2008

233 citations recorded by the source corpus.

Recent observations of the extrasolar planet HD 189733b did not reveal the presence of water in the emission spectrum of the planet. Yet models of such ‘hot-Jupiter’ planets predict an abundance of atmospheric water vapour. Validating and constraining these models is crucial to understanding the physics and chemistry of planetary atmospheres in extreme environments. Indications of the presence of water in the atmosphere of HD 189733b have recently been found in transmission spectra, where the planet’s atmosphere selectively absorbs the light of the parent star, and in broadband photometry. Here we report the detection of strong water absorption in a high-signal-to-noise, mid-infrared emission spectrum of the planet itself. We find both a strong downturn in the flux ratio below 10 µm and discrete spectral features that are characteristic of strong absorption by water vapour. The differences between these and previous observations are significant and admit the possibility that predicted planetary-scale dynamical weather structures may alter the emission spectrum over time. Models that match the observed spectrum and the broadband photometry suggest that heat redistribution from the dayside to the nightside is weak. Reconciling this with the high nightside temperature will require a better understanding of atmospheric circulation or possible additional energy sources.

Subfields: Astronomy and Astrophysics

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. D. Deming
5. D. Sing
6. M. Line
7. H. Knutson
8. M. Marley

Citations in the corpus

• A SYSTEMATIC RETRIEVAL ANALYSIS OF SECONDARY ECLIPSE SPECTRA. II. A UNIFORM ANALYSIS OF NINE PLANETS AND THEIR C TO O RATIOS (2013, background): “Secondary eclipse observations have been made with a variety of instruments including HSTNICMOS (Swain et al. 2009), Spitzer IRAC (Deming et al. 2006; Charbonneau et al. 2008; Knutson et al. 2009; 2012; Agol et al. 2012), MIPS (Knutson et al. 2009; Charbonneau et al. 2008), and IRS (Grillmair et al.”
• An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database (2020, background): “Studies of transiting exoplanets have been able to probe the atmospheres of a small number of these objects (Tsiaras et al. 2018), with observations of water vapor (Grillmair et al. 2008) and carbon monoxide absorption (Konopacky et al. 2013).”
• Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 μm (2013, background): “…scattering from 0.3 to 1 µm (Pont et al. 2008; Sing et al. 2009, 2011; Pont et al. 2013), reports of H2O absorption features at infrared wavelengths (Tinetti et al. 2007; Grillmair et al. 2008; Swain et al. 2008) and claims of CH4 fluorescence at 3.25 µm (Swain et al. 2010; Waldmann et al. 2012).”
• Exoplanet Atmospheres: Physical Processes (2010, background): “Some initial indications from Spitzer spectroscopy that water absorption was absent (Richardson et al. 2007; Grillmair et al. 2007) were superceded by higher S/N data that clearly showed water absorption (Grillmair et al. 2008; Swain et al. 2008, Swain et al 2009a).”
• A CORRELATION BETWEEN STELLAR ACTIVITY AND HOT JUPITER EMISSION SPECTRA (2010, background): “There are currently four planets classified in the literature as having “non-inverted” atmospheres, including HD 189733b (Deming et al. 2006; Grillmair et al. 2007, 2008; Charbonneau et al. 2008; Swain et al. 2009a), TrES-1 (Charbonneau et al. 2005), TrES-3 (Fressin et al. 2010), and WASP-4 (Beerer…”
• 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.…”
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• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, methodology): “ the Hubble Space Telescope (HST) (50, 272). The rst detections of exoplanetary atmospheres using multi-band space-based infrared photometry and spectrophotometry with Spitzer and HST were being made (51, 96, 258). The instruments used for these early measurements (such as the HST NICMOS spectrograp”
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• Equilibrium chemistry down to 100 K (2017, background): “…wavelengths to analyse e.g. the chemical composition of brown dwarfs (see Allard et al. 1997; Helling & Casewell 2014 and references in these reviews) and exoplanets (e.g. Désert et al. 2008; Grillmair et al. 2008; de Kok et al. 2013; Kreidberg et al. 2014; Fraine et al. 2014; Birkby et al. 2017).”
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