A time-dependent radiative model of HD 209458b

By N. Iro, B. Bézard, T. Guillot. 2004

158 citations recorded by the source corpus.

We present a time-dependent radiative model of the atmosphere of HD 209458b and investigate its thermal structure and chemical composition. In a first step, the stellar heating profile and radiative timescales were calculated under planet-averaged insolation conditions. We find that 99.99% of the incoming stellar flux has been absorbed before reaching the 7 bar level. Stellar photons cannot therefore penetrate deeply enough to explain the large radius of the planet. We derive a radiative time constant which increases with depth and reaches about 8 h at 0.1 bar and 2.3 days at 1 bar. Time-dependent temperature profiles were also calculated, in the limit of a zonal wind that is independent of height (i.e. solid-body rotation) and constant absorption coefficients. We predict day-night variations of the effective temperature of ~600 K, for an equatorial rotation rate of 1 km s -1 , in good agreement with the predictions by Showmann & Guillot (2002). This rotation rate yields day-to-night temperature variations in excess of 600 K above the 0.1-bar level. These variations rapidly decrease with depth below the 1-bar level and become negligible below the ~5-bar level for rotation rates of at least 0.5 km s -1 . At high altitudes (mbar pressures or less), the night temperatures are low enough to allow sodium to condense into Na 2 S. Synthetic transit spectra of the visible Na doublet show a much weaker sodium absorption on the morning limb than on the evening limb. The calculated dimming of the sodium feature during planetary transites agrees with the value reported by Charbonneau et al. (2002).

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/760c18dd42f1f68d05d927d6290785782312900d

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In Astronomy and Astrophysics

1. Jon Fortney
2. M. Marley
3. A. Showman
4. N. Madhusudhan
5. V. Parmentier
6. R. Freedman
7. Adam Burrows
8. T. Guillot

Citations in the corpus

• Atmospheric circulation of tidally locked exoplanets: a suite of benchmark tests for dynamical solvers (2010, methodology): “1 of Iro et al. (2005): TIro 1 K = 1696.6986 + 132.231 80P̃ − 174.304 59P̃ 2 + 12.579 612P̃ 3 + 59.513 639P̃ 4 + 9.670 6522P̃ 5 − 4.113 6048P̃ 6 − 1.063 2301P̃ 7 + 0.064 400 203P̃ 8 + 0.035 974 396P̃ 9 + 0.002 574 0066P̃ 10.”
• 3D mixing in hot Jupiters atmospheres. I. Application to the day/night cold trap in HD 209458b (2013, background): “This is true for the radiative time constant, which varies significantly from low to high pressure (Iro et al. 2005; Showman et al. 2008).”
• ATMOSPHERIC CIRCULATION OF HOT JUPITERS: COUPLED RADIATIVE-DYNAMICAL GENERAL CIRCULATION MODEL SIMULATIONS OF HD 189733b and HD 209458b (2008, unknown): “At first glance, this vertical coherency is surprising, because idealized radiative calculations have shown that the radiative time constant should vary by orders of magnitude over this pressure range (Iro et al. 2005; Fortney et al. 2008; Showman et al. 2008a).”
• ATMOSPHERIC CHEMISTRY IN GIANT PLANETS, BROWN DWARFS, AND LOW-MASS DWARF STARS. III. IRON, MAGNESIUM, AND SILICON (2010, background): “…= 2600 K, log g = 5.0; Tsuji et al. 1996), an L dwarf (Teff = 1800 K, log g = 5.0; Burrows et al. 2006), the hot, closein (Pegasi) planet HD209458b (Teff = 1350 K; Iro et al. 2005), the T dwarf Gliese 229B (Teff = 960 K; Marley et al. 1996), and Jupiter (Teff = 124 K), indicated by dashed lines.”
• CAN TiO EXPLAIN THERMAL INVERSIONS IN THE UPPER ATMOSPHERES OF IRRADIATED GIANT PLANETS? (2009, background): “Iro et al. (2005) suggest that if, as expected, HD 209458b is in synchronous rotation, then Na might have condensed into Na2S on the colder night side, which could in part explain an inferred low abundance of atomic Na.”
• Phase-dependent Properties of Extrasolar Planet Atmospheres (2005, background): “The decline in temperature above the nearly isothermal photosphere (P < 0.01 bar) for the hottest portions of the dayside is consistent with recent works by other groups (Sudarsky et al. 2003; Fortney et al. 2005; Iro et al. 2005).”
• A chemical model for the atmosphere of hot Jupiters (2012, methodology): “10) and HD 209458b, we used a line-by-line radiative transfer model from 0.3 to 25 μm (Iro et al. 2005; Iro & Deming 2010).”
• Atmosphere, Interior, and Evolution of the Metal-rich Transiting Planet HD 149026b (2005, background): “These dynamical models (e.g. Cooper & Showman 2005b; Showman & Guillot 2002) and the work of Iro et al. (2005) and Seager et al. (2005) show these flux redistribution issues are likely to be more complex that than a simple F/4 or F/2 factor.”
• The effect of condensates on the characterization of transiting planet atmospheres with transmission spectroscopy (2005, background): “Recently Iro et al. (2005) have shown that a substantial day-night temperature contrast in the planet’s atmosphere could lead to a sink of atomic c© 2005 RAS sodium, as the atom could be tied up into the condensate Na2S on the planet’s night side.”
• Dynamics and Disequilibrium Carbon Chemistry in Hot Jupiter Atmospheres, with Application to HD 209458b (2006, methodology): “Iro et al. (2005) calculated a line-by-line solution to the monochromatic radiative transfer equation using the Goukenleuque et al. (2000) model.”
• DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b (2011, background): “…the inferred presence of hazes, clouds, and Rayleigh scatterers that can affect atmospheric spectral behavior (e.g., Charbonneau et al. 2002; Fortney et al. 2003; Fortney 2005; Iro et al. 2005; Pont et al. 2008; Lecavelier des Etangs et al. 2008a,b; Sing et al. 2008a,b, 2009; Shabram et al. 2011).”
• A correlation between the heavy element content of transiting extrasolar planets and the metallicity of their parent stars (2006, methodology): “…as the difference between the measured radius and the one calculated using a simple evolution model for a solar composition gaseous planet. temperatures in the literature can vary by up to 500 K (Barman et al. 2001; Sudarsky et al. 2003; Fortney et al. 2005; Iro et al. 2005; Seager et al. 2005).”
• TRANSMISSION SPECTRA OF THREE-DIMENSIONAL HOT JUPITER MODEL ATMOSPHERES (2009, background): “Previously Iro et al. (2005) showed a similar effectfor a 3D model of HD 209458b that included radiative transfer and parameterized winds.”