Detection of carbon monoxide in the high-resolution day-side spectrum of the exoplanet HD 189733b

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

192 citations recorded by the source corpus.

Context. After many attempts over more than a decade, high-resolution spectroscopy has recently delivered its first detections of molecular absorption in exoplanet atmospheres, both in transmission and thermal emission spectra. Targeting the combined signal from individual lines in molecular bands, these measurements use variations in the planet radial velocity to separate the planet signal from telluric and stellar contaminants. Aims: We apply high-resolution spectroscopy to probe molecular absorption in the day-side spectrum of the bright transiting hot Jupiter HD 189733b. Methods: We observed HD 189733b with the CRIRES high-resolution near-infrared spectograph on the Very Large Telescope during three nights, targeting possible absorption from carbon monoxide, water vapour, methane, and carbon dioxide, at 2.0 and 2.3 {$μ$}m. Results: We detect a 5-{$σ$} absorption signal from CO at a contrast level of ~{}4.5 { imes} 10$^{-4}$ with respect to the stellar continuum, revealing the planet orbital radial velocity at 154$^{+4}$$_{-3}$ km s$^{-1}$. This allows us to solve for the planet and stellar mass in a similar way as for stellar eclipsing binaries, resulting in 0.846$^{+0.068}$$_{-0.049}$M{sun} and M$_p$ = 1.162$^{+0.058}$$_{-0.039}$ M$^{Jup}$. No significant absorption is detected from H$_{2}$O, CO$_{2}$, or CH$_{4}$ and we determine upper limits on their line contrasts. Conclusions: The detection of CO in the day-side spectrum of HD 189733b can be made consistent with the haze layer proposed to explain the optical to near-infrared transmission spectrum if the layer is optically thin at the normal incidence angles probed by our observations, or if the CO abundance is high enough for the CO absorption to originate from above the haze. Our non-detection of CO$_{2}$ at 2.0 {$μ$}m is not inconsistent with the deep CO$_{2}$ absorption from low-resolution NICMOS secondary eclipse data in the same wavelength range. If genuine, the absorption would be so strong that it blanks out any planet light completely in this wavelength range, leaving no high-resolution signal to be measured. Based on observations collected at the European Southern Observatory (186.C-0289).

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2f928668a795e6121416e4a4cbde18b0c915b8aa

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Citations in the corpus

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).”
A Population Study of Gaseous Exoplanets (2017, background): “Whilst individual case-studies of hotJupiters (e.g. Brogi et al. 2013; de Kok et al. 2013; Deming et al. 2013; Konopacky et al. 2013; Mandell et al. 2013; Todorov et al. 2013; McCullough et al. 2014; Snellen et al. 2014; Stevenson et al. 2014b; Zellem et al. 2014; Macintosh et al. 2015; Kreidberg…”
The 2020 release of the ExoMol database: Molecular line lists for exoplanet and other hot atmospheres (2020, unknown): “resolution Doppler spectroscopy [277–279].”
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).”
Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 μm (2013, methodology): “Here, we build upon the method of singular value decompositions (SVDs) used by de Kok et al. (2013) to identify carbon monoxide absorption in high-resolution spectra of the day side of HD 189733 b at 2.3 µm.”
Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b (2014, methodology): “For example, as shown in (de Kok et al. 2013a), the region around 3.5 µm is expected to contain the detectable signatures of H2O, CO2, and CH4.”
Combining high-dispersion spectroscopy with high contrast imaging : Probing rocky planets around our nearest neighbors (2015, background): “E P] 3 M ar transiting planet τBöotis b, determining its mass and orbital inclination (see also Rodler et al. 2012), and it was also detected in the thermal spectra of HD 189733 b (de Kok et al. 2013; Rodler et al. 2013) and tentatively 51 Peg b (Brogi et al. 2013).”
ROTATION AND WINDS OF EXOPLANET HD 189733 b MEASURED WITH HIGH-DISPERSION TRANSMISSION SPECTROSCOPY (2015, methodology): “We note that these transit data are less e↵ective than previous dayside observations (Brogi et al. 2012, 2014; Birkby et al. 2013; de Kok et al. 2013) in constraining the amplitude of the planet orbital radial velocity (K P ), resulting in much larger error bars.”