WATER VAPOR IN THE SPECTRUM OF THE EXTRASOLAR PLANET HD 189733b. I. THE TRANSIT

By P. McCullough, N. Crouzet, D. Deming, N. Madhusudhan. 2014

201 citations recorded by the source corpus.

We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 μm to 1.7 μm and spatially scanned the image across the detector at 2″ s−1. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 μm and 1.4 μm water vapor features are, respectively, 83 ± 53 ppm and 200 ± 47 ppm greater than the local minimum at 1.3 μm. We compare the WFC3 spectrum with the composite transit spectrum of HD 189733b assembled by Pont et al., extending from 0.3 μm to 24 μm. Although the water vapor features in the WFC3 spectrum are compatible with the model of non-absorbing, Rayleigh-scattering dust in the planetary atmosphere, we also re-interpret the available data with a clear planetary atmosphere. In the latter interpretation, the slope of increasing transit depth with shorter wavelengths from the near infrared, through the visible, and into the ultraviolet is caused by unocculted star spots, with a smaller contribution of Rayleigh scattering by molecular hydrogen in the planet's atmosphere. At relevant pressures along the terminator, our model planetary atmosphere's temperature is ∼700 K, which is below the condensation temperatures of sodium- and potassium-bearing molecules, causing the broad wings of the spectral lines of Na i and K i at 0.589 μm and 0.769 μm to be weak.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c05aa4e7f4d7e9907f86e64850c71fa6905cf0fb

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Line
5. D. Sing
6. J. D'esert
7. V. Parmentier
8. M. Marley

In Instrumentation

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Line
5. D. Sing
6. J. D'esert
7. V. Parmentier
8. Laura Kreidberg

Citations in the corpus

• DETECTION OF AN ATMOSPHERE AROUND THE SUPER-EARTH 55 CANCRI E (2015, methodology): “…the saturation of the detector and has already been successfully used to provide an increasing number of exoplanetary spectra (e.g. Deming et al. 2013; Knutson et al. 2014a,b; Kreidberg et al. 2014a,b, 2015; McCullough et al. 2014; Crouzet et al. 2014; Fraine et al. 2014; Stevenson et al. 2014).”
• TOWARD CHEMICAL CONSTRAINTS ON HOT JUPITER MIGRATION (2014, background): “It is unclear if clouds are responsible for the muted H2O features (Madhusudhan et al. 2014; McCullough et al. 2014), and the low H2O may indeed represent the bulk atmospheric composition.”
• NO THERMAL INVERSION AND A SOLAR WATER ABUNDANCE FOR THE HOT JUPITER HD 209458B FROM HST/WFC3 SPECTROSCOPY (2016, background): “…exoplanets are rapidly transforming our knowledge of planetary atmospheres (Berta et al. 2012; Swain et al. 2012; Deming et al. 2013; Huitson et al. 2013; Kreidberg et al. 2014ab,15; Stevenson et al. 2014c; McCullough et al. 2014; Knutson et al. 2014; Fraine et al. 2014; Evans et al. 2016).”
• THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA (2015, background): “The amplitude of the slope could either be do to scattering hazes (Sing et al. 2008) or to a lesser effect, star spots (McCullough et al. 2014).”
• CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST (2015, background): “HST WFC3 dayside spectra of several hot Jupiters are consistent with cloud-free atmospheres (McCullough et al. 2014; Stevenson et al. 2014; Kataria et al. 2015), so we do know that clouds do not suppress spectral features in emission spectra of all planets.”
• A CONSISTENT RETRIEVAL ANALYSIS OF 10 HOT JUPITERS OBSERVED IN TRANSMISSION (2016, background): “McCullough et al. (2014) postulate that it is possible to explain the broad spectral shape of the HD 189733b observations with starspots alone, without invoking the presence of clouds, and under this assumption they are able to fit the spectrum with a clear solar composition atmosphere model.”
• DETECTION OF H2O AND EVIDENCE FOR TiO/VO IN AN ULTRA-HOT EXOPLANET ATMOSPHERE (2016, background): “In the near-infrared, water absorption has now been robustly measured for a number of planets, both in transmission and emission (e.g. Deming et al. 2013; Wakeford et al. 2013; Stevenson et al. 2014; McCullough et al. 2014; Kreidberg et al. 2015).”
• The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets (2017, background): “…planet-to-star radius ratio), Fλ,phot is the spectrum of the photosphere, Fλ,het is the spectrum of a photospheric heterogeneity (i.e., spots or faculae), and fhet is the fraction of the projected stellar disk covered by the heterogeneity (see also McCullough et al. 2014, Equation (1)).”
• Transmission spectral properties of clouds for hot Jupiter exoplanets (2014, background): “…(2010) model of HD 189733b which has a 1000× enhanced scattering to estimate the amplitude and relative location of molecular features in the transmission spectrum, fitting for the HD 189733b transmission data (Pont et al. 2013; McCullough et al. 2014) by allowing only the model altitude to vary.”
• A NEW APPROACH TO ANALYZING HST SPATIAL SCANS: THE TRANSMISSION SPECTRUM OF HD 209458 b (2015, methodology): “…has already been successfully used angelos.tsiaras.14@ucl.ac.uk to provide an increasing number of exoplanetary spectra (e.g. Deming et al. 2013; McCullough et al. 2014; Crouzet et al. 2014; Fraine et al. 2014; Knutson et al. 2014a,b; Kreidberg et al. 2014a,b; Stevenson et al. 2014; Kreidberg…”
• A Population Study of Gaseous Exoplanets (2017, background): “…HAT-P-1 b (Wakeford et al. 2013), HAT-P-11 b (Fraine et al. 2014), HAT-P32 b (Damiano et al. 2017), HD 209458 b (Deming et al. 2013), HD 189733 b (McCullough et al. 2014), WASP12 b (Kreidberg et al. 2015), WASP-31 b (Sing et al. 2015), WASP-43 b (Kreidberg et al. 2014a), WASP-101 b (Wakeford et…”
• A PRECISE WATER ABUNDANCE MEASUREMENT FOR THE HOT JUPITER WASP-43b (2014, methodology): “E P] 8 O ct 2 01 4 2 Kreidberg et al. 2014) and consistent measurements with multiple anaylsis techniques (Deming et al. 2013; Kreidberg et al. 2014; Knutson et al. 2014; McCullough et al. 2014).”