The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations

By F. Pont, D. Sing, Neale P. Gibson, Suzanne Aigrain, G.Henry, N. H. Exeter, Oxford, Eső, T. State. 2012

326 citations recorded by the source corpus.

The hot Jupiter HD 189733b is the most extensively observed exoplanet. Its atmosphere has been detected and characterized in transmission and eclipse spectroscopy, and its phase curve measured at several wavelengths. This paper brings together the results of our campaign to obtain the complete transmission spectrum of the atmosphere of this planet from UV to infrared with the Hubble Space Telescope, using the STIS, ACS and WFC3 instruments. We provide a new tabulation of the transmission spectrum across the entire visible and infrared range. The radius ratio in each wavelength band was re-derived, where necessary, to ensure a consistent treatment of the bulk transit parameters and stellar limb darkening. Special care was taken to correct for, and derive realistic estimates of the uncertainties due to, both occulted and unocculted star spots. The combined spectrum is very different from the predictions of cloud-free models for hot Jupiters: it is dominated by Rayleigh scattering over the whole visible and near-infrared range, the only detected features being narrow sodium and potassium lines. We interpret this as the signature of a haze of condensate grains extending over at least five scaleheights. We show that a dust-dominated atmosphere could also explain several puzzling features of the emission spectrum and phase curves, including the large amplitude of the phase curve at 3.6 μm, the small hotspot longitude shift and the hot mid-infrared emission spectrum. We discuss possible compositions and derive some first-order estimates for the properties of the putative condensate haze/clouds. We finish by speculating that the dichotomy between the two observationally defined classes of hot Jupiter atmospheres, of which HD 189733b and HD 209458b are the prototypes, might not be whether they possess a temperature inversion, but whether they are clear or dusty. We also consider the possibility of a continuum of cloud properties between hot Jupiters, young Jupiters and L-type brown dwarfs.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b5d7816ba307a57901d1e61c6376d84abd2d43fc

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. D. Sing
5. D. Deming
6. D. Charbonneau
7. H. Knutson
8. J. D'esert

Citations in the corpus

• An HST optical-to-near-IR transmission spectrum of the hot Jupiter WASP-19b: detection of atmospheric water and likely absence of TiO (2013, background): “…is a possibility of the planet crossing a bright region on the star, such crossings have not been observed with the more active system HD 189733b (Pont et al. 2013) and we find in Section 3.3.2 that for 1000 Å spectral bins, these deviations from the expected transit model are not correlated…”
• HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water (2017, background): “Alternatively, they may be explained by invoking a high altitude (P <1 mbar) opaque cloud deck (Deming et al. 2013) or uniform-in-altitude grey opacity, such as haze particles (Pont et al. 2013).”
• Observations of Transiting Exoplanets with the James Webb Space Telescope (JWST) (2014, background): “Starspots can greatly complicate the interpretation of transit data as a planet scans across a mottled stellar surface, changing the apparent depth of a transit from its true value or producing a flux change if the planet itself occults a starspot (Pont et al. 2013; Huitson et al. 2013).”
• A CONSISTENT RETRIEVAL ANALYSIS OF 10 HOT JUPITERS OBSERVED IN TRANSMISSION (2016, methodology): “Pont et al. (2013) describe star spot corrections for stitching of HD 189733b, based on ground-based monitoring of the stellar flux over several years.”
• Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph (2015, methodology): “Furthermore, with these same observations Di Gloria (in prep.) detected a slope in the ratios of the planet-star radius that Pont et al. (2008, 2013) interpreted as Rayleigh scattering.”
• SPITZER PHASE CURVE CONSTRAINTS FOR WASP-43b AT 3.6 AND 4.5 μm (2016, background): “If present on the planet dayside, condensates in a hot-Jupiter atmosphere can modify the measured redistribution of heat (Pont et al. 2013).”
• The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets (2017, background): “…in transit spectroscopy studies to constrain the contribution of unocculted photospheric heterogeneities to exoplanet transmission spectra (Pont et al. 2008; Sing et al. 2011; Huitson et al. 2013; Jordán et al. 2013; Pont et al. 2013; Fraine et al. 2014; Sing et al. 2016; Rackham et al. 2017).”
• INFRARED TRANSMISSION SPECTROSCOPY OF THE EXOPLANETS HD 209458b AND XO-1b USING THE WIDE FIELD CAMERA-3 ON THE HUBBLE SPACE TELESCOPE (2013, result): “• Our results are consistent with the situation described by Pont et al. (2013) for HD 189733b, wherein weak molecular absorptions are superposed on a spectrum whose broad variations with wavelength in transit are dominated by haze and/or dust opacity.”
• 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): “…to date, with strong evidence for a high-altitude haze that causes Rayleigh 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…”
• Transmission spectral properties of clouds for hot Jupiter exoplanets (2014, methodology): “E P] 3 0 Se p 20 14 erties, with their spectra dominated by strong optical Rayleigh and / or Mie scattering from high-altitude aerosol particles (Pont et al. 2008, 2013; Sing et al. 2009, 2011, 2013; Gibson et al. 2013).”
• WATER VAPOR IN THE SPECTRUM OF THE EXTRASOLAR PLANET HD 189733b. I. THE TRANSIT (2014, methodology): “If so, then there would be no need for Rayleigh-scattering, nonabsorbing dust in the atmosphere of HD 189733b in order to match the slope in the apparent transit depth with wavelength from 0.3µm to 1.0µm as in the interpretation of Pont et al. (2013).”
• SOAP 2.0: A TOOL TO ESTIMATE THE PHOTOMETRIC AND RADIAL VELOCITY VARIATIONS INDUCED BY STELLAR SPOTS AND PLAGES (2014, result): “In Pont et al. (2013), the temperature difference of a spot occulted during the transit of HD189733b is estimated to be −750±250 K, compatible with our value of −663 K adopted in SOAP 2.0.”
• HST hot-Jupiter transmission spectral survey: evidence for aerosols and lack of TiO in the atmosphere of WASP-12b (2013, background): “Pont et al. (2013) explored the case where the atmospheric opacity is dominated by Rayleigh scattering from grains of condensates, with the density and maximum size of the grains varying with pressure (settling grains).”
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering (2014, background): “There is a growing body of evidence for substantial clouds and hazes in hot Jupiters, including the transmission spectra of HD 189733b, WASP-12b, HATP-32b, and WASP-6b (Pont et al. 2013; Sing et al. 2011b, 2013; Gibson et al. 2013; Nikolov et al. 2014a).”
• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, background): “The effect of clouds/hazes on exoplanetary transmission spectra is evident through (a) subdued spectral features of prominent chemical species (63), and (b) slopes in optical spectra that are deviant from gaseous Rayleigh scattering (209).”