THE EFFECTS OF IRRADIATION ON HOT JOVIAN ATMOSPHERES: HEAT REDISTRIBUTION AND ENERGY DISSIPATION
- JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)
- ETH Zuerich, Institute for Astronomy, Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland)
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)
Hot Jupiters, due to the proximity to their parent stars, are subjected to a strong irradiating flux that governs their radiative and dynamical properties. We compute a suite of three-dimensional circulation models with dual-band radiative transfer, exploring a relevant range of irradiation temperatures, both with and without temperature inversions. We find that, for irradiation temperatures T{sub irr} {approx}< 2000 K, heat redistribution is very efficient, producing comparable dayside and nightside fluxes. For T{sub irr} Almost-Equal-To 2200-2400 K, the redistribution starts to break down, resulting in a high day-night flux contrast. Our simulations indicate that the efficiency of redistribution is primarily governed by the ratio of advective to radiative timescales. Models with temperature inversions display a higher day-night contrast due to the deposition of starlight at higher altitudes, but we find this opacity-driven effect to be secondary compared to the effects of irradiation. The hotspot offset from the substellar point is large when insolation is weak and redistribution is efficient, and decreases as redistribution breaks down. The atmospheric flow can be potentially subjected to the Kelvin-Helmholtz instability (as indicated by the Richardson number) only in the uppermost layers, with a depth that penetrates down to pressures of a few millibars at most. Shocks penetrate deeper, down to several bars in the hottest model. Ohmic dissipation generally occurs down to deeper levels than shock dissipation (to tens of bars), but the penetration depth varies with the atmospheric opacity. The total dissipated Ohmic power increases steeply with the strength of the irradiating flux and the dissipation depth recedes into the atmosphere, favoring radius inflation in the most irradiated objects. A survey of the existing data, as well as the inferences made from them, reveals that our results are broadly consistent with the observational trends.
- OSTI ID:
- 22037233
- Journal Information:
- Astrophysical Journal, Vol. 751, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
COMPUTERIZED SIMULATION
ENERGY LOSSES
HEAT
HELMHOLTZ INSTABILITY
IRRADIATION
LAYERS
OPACITY
PENETRATION DEPTH
PLANETARY ATMOSPHERES
PLANETS
RADIANT HEAT TRANSFER
RICHARDSON NUMBER
SATELLITE ATMOSPHERES
STARS
TEMPERATURE INVERSIONS
THREE-DIMENSIONAL CALCULATIONS