MULTIWAVELENGTH CONSTRAINTS ON THE DAY–NIGHT CIRCULATION PATTERNS OF HD 189733b

By H. Knutson, D. Charbonneau, N. Cowan, Jon Fortney, A. Showman, E. Agol, G. Henry, Mark E. Everett, L. Allen. 2008

201 citations recorded by the source corpus.

We present new Spitzer observations of the phase variation of the hot Jupiter HD 189733b in the MIPS 24 μm bandpass, spanning the same part of the planet's orbit as our previous observations in the IRAC 8 μm bandpass (Knutson et al. ). We find that the minimum hemisphere-averaged flux from the planet in this bandpass is 76% ± 3% of the maximum flux; this corresponds to minimum and maximum hemisphere-averaged brightness temperatures of 984 ± 48 K and 1220 ±  47 K, respectively. The planet reaches its maximum flux at an orbital phase of 0.396 ± 0.022, corresponding to a hot region shifted 20°–30° east of the substellar point. Because tidally locked hot Jupiters would have enormous day–night temperature differences in the absence of winds, the small amplitude of the observed phase variation indicates that the planet's atmosphere efficiently transports thermal energy from the day side to the night side at the 24 μm photosphere, leading to modest day–night temperature differences. The similarities between the 8 and 24 μm phase curves for HD 189733b lead us to conclude that the circulation on this planet behaves in a fundamentally similar fashion across the range of pressures sensed by these two wavelengths. One-dimensional radiative transfer models indicate that the 8 μm band should probe pressures 2–3 times greater than at 24 μm, although the uncertain methane abundance complicates the interpretation. If these two bandpasses do probe different pressures, it would indicate that the temperature varies only weakly between the two sensed depths, and hence that the atmosphere is not convective at these altitudes. We also present an analysis of the possible contribution of star spots to the time series at both 8 and 24 μm based on near-simultaneous ground-based observations and additional Spitzer observations. Accounting for the effects of these spots results in a slightly warmer night-side temperature for the planet in both bandpasses, but does not otherwise affect our conclusions.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/581df07ac8f3d2bb4b2afb8dfcb05ab53be30829

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. D. Deming
5. D. Charbonneau
6. D. Sing
7. H. Knutson
8. J. D'esert

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): “…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. 2007; 2008) spanning ∼1.5 µm to ∼25 µm.”
• DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b (2011, background): “…on the source of the absorber responsible for the stratospheric thermal inversions inferred for HD 209458b and other exoplanets (e.g., Burrows et al. 2007, 2008; Knutson et al. 2008, 2009; Fortney et al. 2008a; Machalek et al. 2009, 2010; Madhusudhan & Seager 2009, 2010a; O’Donovan et al. 2010).”
• EQUATORIAL SUPERROTATION ON TIDALLY LOCKED EXOPLANETS (2011, background): “…constraints on the three-dimensional temperature structure of several hot Jupiters, which hint at a vigorous atmospheric circulation on these bodies (e.g., Knutson et al. 2007, 2009; Charbonneau et al. 2008; Harrington et al. 2006; Cowan et al. 2007; Swain et al. 2009; Crossfield et al. 2010).”
• ATMOSPHERIC CIRCULATION OF HOT JUPITERS: COUPLED RADIATIVE-DYNAMICAL GENERAL CIRCULATION MODEL SIMULATIONS OF HD 189733b and HD 209458b (2008, unknown): “Overlaid are the Knutson et al. (2007) 8-µm light curve in small blue dots and the binned Knutson et al. (2009) 24-µm light curve in small magenta diamonds, along with theSpitzersecondary-eclipse depths from Charbonneau et al. (2008) and Deming et al. (2006) in large diamonds.”
• 3D mixing in hot Jupiters atmospheres. I. Application to the day/night cold trap in HD 209458b (2013, background): “A shift of the hottest point of the planet eastward from the substellar point has been dirctly observed in several exoplanets (Knutson et al. 2007, 2009, 2012; Crossfield et al. 2010) and interpreted as a direct consequence of this jet.”
• A TEMPERATURE AND ABUNDANCE RETRIEVAL METHOD FOR EXOPLANET ATMOSPHERES (2009, background): “Here we will discuss the contribution to the net emergent flux from the surface elements at the top of the atmosphere (see Knutson et al. 2009b for a discussion of radial contribution functions).”
• ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b (2013, methodology): “As seen in Figure 4, the 8.0 µm data exhibit the well know asymptotic increase in flux (e.g. Knutson et al. 2007, 2009a; Agol et al. 2010).”
• Exoplanet Atmospheres: Physical Processes (2010, background): “…shows an 8 µm brightness temperature variation of over 200 K from a minimum brightness temperature of 973±33K to a maximum brightness temperature of 1212±11K (Knutson et al. 2007a), and a thermal brightness change at 24 µm consistent with the 8 µm data within the errors (Knutson et al. 2009c).”
• THERMAL PHASE VARIATIONS OF WASP-12b: DEFYING PREDICTIONS (2011, unknown): “…for non-transiting short-period planets (Cowan et al. 2007; Crossfield et al. 2010), but are most potent when combined with transit and eclipse observations for edge-on systems, because of the additional knowledge of the planet’s inclination, mass, and radius (Knutson et al. 2007, 2009a, 2009b).”
• TRANSMISSION SPECTRA OF THREE-DIMENSIONAL HOT JUPITER MODEL ATMOSPHERES (2009, background): “…has been able to reproduce most of the secondary eclipse pho- tometry and spectroscopy, the broad features of the 8 and 24µm half-orbit light curves (Knutson et al. 2007a, 2009), and some features of the transmission spectrum (although an unmodeled haze apparently dominates in the optical and…”
• WATER VAPOR IN THE SPECTRUM OF THE EXTRASOLAR PLANET HD 189733b. I. THE TRANSIT (2014, methodology): “To start, we adopt the limiting-case in which all of the observed planetary radius increase in the blue and UV is due to unocculted star spots and the spot-free radius ratioRp/Rs is 0.15459, from the longest wavelength transit measurement at 24µm (Knutson et al. 2009; Pont et al. 2013).”
• Evaporation of the planet HD 189733b observed in H I Lyman-α (2010, background): “The short period of the planet (2.21858 days) has been measured precisely (Hébrard & Lecavelier des Etangs 2006; Knutson et al. 2009).”
• A chemical model for the atmosphere of hot Jupiters (2012, methodology): “…observational data are superimposed on the spectra (Charbonneau et al. 2008; Grillmair et al. 2008; Swain et al. 2009b, for emission spectrum) and (Knutson et al. 2007, 2009; Swain et al. 2008b; Beaulieu et al. 2008; Sing et al. 2009; Désert et al. 2009; Agol et al. 2010, for transmission…”
• The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations (2012, methodology): “The issue of infrared features is discussed in detail in Gibson et al. (2011) for the 1-2 µm range and Désert et al. (2011) at longer wavelengths.”
• 3.6 AND 4.5 μm PHASE CURVES AND EVIDENCE FOR NON-EQUILIBRIUM CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HD 189733b (2012, methodology): “…is an active K0 star with a Ca II H & K emission line strength of log(R′HK)= −4.5 (Bouchy et al. 2005; Knutson et al. 2010), which has been observed to vary by as much as ±1.5% at visible wavelengths with a rotation period of 11.95 days (Henry & Winn 2008; Knutson et al. 2009a; Lanza et al. 2011).”
• Hubble Space Telescope transmission spectroscopy of the exoplanet HD 189733b: high‐altitude atmospheric haze in the optical and near‐ultraviolet with STIS (2011, methodology): “…also covers the HD189733 stellar activity during the epochs of the HST transmission spectra from Pont et al. (2007), Swain, Vasisht & Tinetti (2008) and Sing et al. (2009), and as well as the Spitzer transit photometry of Désert et al. (2009), Knutson et al. (2009), and Désert et al. (2011).”
• SEARCH FOR CARBON MONOXIDE IN THE ATMOSPHERE OF THE TRANSITING EXOPLANET HD 189733b (2009, background): “The short period of the planet (∼2.21858 days) is known with high accuracy (Hébrard & Lecavelier des Etangs 2006; Knutson et al. 2009).”