Protoplanetary Disks Including Radiative Feedback From Accreting Exoplanets

Protoplanetary disks including radiative feedback from accreting planets

Authors:

Montesinos et al

Abstract:

While recent observational progress is converging on the detection of compact regions of thermal emission due to embedded protoplanets, further theoretical predictions are needed to understand the response of a protoplanetary disk to the planet formation radiative feedback. This is particularly important to make predictions for the observability of circumplanetary regions. In this work we use 2D hydrodynamical simulations to examine the evolution of a viscous protoplanetary disk in which a luminous Jupiter-mass planet is embedded. We use an energy equation which includes the radiative heating of the planet as an additional mechanism for planet formation feedback. Several models are computed for planet luminosities ranging from 10−5 to 10−3 Solar luminosities. We find that the planet radiative feedback enhances the disk's accretion rate at the planet's orbital radius, producing a hotter and more luminous environement around the planet, independently of the prescription used to model the disk's turbulent viscosity. We also estimate the thermal signature of the planet feedback for our range of planet luminosities, finding that the emitted spectrum of a purely active disk, without passive heating, is appreciably modified in the infrared. We simulate the protoplanetary disk around HD 100546 where a planet companion is located at about 68 au from the star. Assuming the planet mass is 5 Jupiter masses and its luminosity is ∼2.5×10−4L⊙, we find that the radiative feedback of the planet increases the luminosity of its ∼5 au circumplanetary disk from 10−5L⊙ (without feedback) to 10−3L⊙, corresponding to an emission of ∼1mJy in L′ band after radiative transfer calculations, a value that is in good agreement with HD 100546b observations.

A Model for Young Giant Exoplanets Applied beta Pictoris b

A radiative-convective equilibrium model to study young giant exoplanets by direct imaging

Authors:

Baudino et al

Abstract:

We developed a model for young giant exoplanets (Exoplanet Radiative-convective Equilibrium Model or Exo-REM). Input parameters are planet's surface gravity (g), effective temperature (Teff ) and elemental composition. Under the additional assumption of thermochemical equilibrium, the model predicts the equilibrium temperature profile and mixing ratio profiles of the most important gases. Opacity sources include the H2-He collision-induced absorption and molecular lines from H2O, CO, CH4 (updated with the Exomol linelist), NH3, VO, TiO, Na and K. Absorption by iron and silicate cloud particles is added above the expected condensation levels with a fixed scale height and a given optical depth at some reference wavelength. Scattering was not included at this stage.

We applied Exo-REM to photometric and spectral observations of the planet beta Pictoris b obtained in a series of near IR filters. We derived Teff = 1550 ± 150 K, log(g) = 3.5 ± 1, and a radius R = 1.76 ± 0.24 R Jup (2-σ error bars). These values are comparable to those found in the literature, although with more conservative error bars, but consistent with the model accuracy. We finally investigated the precision to which the above parameters can be constrained from SPHERE measurements using different sets of near IR filters as well as near low resolution spectroscopy.

Three Hot Jupiters and a Single Brown Dwarf Observed by the Canada-France-Hawaii Telescope

Near-infrared Thermal Emission Detections of a number of hot Jupiters and the Systematics of Ground-based Near-infrared Photometry

Authors:

Croll et al

Abstract:

We present detections of the near-infrared thermal emission of three hot Jupiters and one brown-dwarf using the Wide-field Infrared Camera (WIRCam) on the Canada-France-Hawaii Telescope (CFHT). These include Ks-band secondary eclipse detections of the hot Jupiters WASP-3b and Qatar-1b and the brown dwarf KELT-1b. We also report Y-band, KCONT-band, and two new and one reanalyzed Ks-band detections of the thermal emission of the hot Jupiter WASP-12b. We present a new reduction pipeline for CFHT/WIRCam data, which is optimized for high precision photometry. We also describe novel techniques for constraining systematic errors in ground-based near-infrared photometry, so as to return reliable secondary eclipse depths and uncertainties. We discuss the noise properties of our ground-based photometry for wavelengths spanning the near-infrared (the YJHK-bands), for faint and bright-stars, and for the same object on several occasions. For the hot Jupiters WASP-3b and WASP-12b we demonstrate the repeatability of our eclipse depth measurements in the Ks-band; we therefore place stringent limits on the systematics of ground-based, near-infrared photometry, and also rule out violent weather changes in the deep, high pressure atmospheres of these two hot Jupiters at the epochs of our observations.

How Hot Jupiter WASP-3b Cooks

The thermal emission of the exoplanet WASP-3b

Authors:

Rostron et al

Abstract:

We report the detection of thermal emission from the transiting hot Jupiter WASP-3b at 3.6, 4.5 and 8.0 μm using the Spitzer Space Telescope. We obtain planet-to-star flux ratios of 0.209+0.040−0.028, 0.282 ± 0.012 and 0.328+0.086−0.055 per cent at these wavelengths, respectively, implying infrared brightness temperatures of T3.6μm=2280+210−150K, T4.5 μm = 2400 ± 80 K and T8.0μm=2210+390−250K. We find that WASP-3b falls into an emerging class of highly irradiated planets whose measured temperatures suggest that the planets are dark and redistribute heat around the planet inefficiently. The latter is similarly concluded from 1D atmospheric model comparisons, which also favour the presence of an atmospheric temperature inversion. We compare the WASP-3 system to the proposed inversion–activity relation, finding that it hints at a more complex relation than a simple cut-off in activity implied by previous data. Using eclipse timings we also constrain e cos ω to be −0.0006+0.0010−0.0006, suggesting that the eccentricity of WASP-3b can only be large for a narrow range of ω.