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Ultracool dwarfs exhibit a remarkably varied set of characteristics which hint at the complex physical processes acting in their atmospheres and interiors. Spectra of these objects not only depend upon their mass and effective temperature, but also their atmospheric chemistry, weather, and dynamics. As a consequence divining their mass, metallicity and age solely from their spectra has been a challenge...
Some wave features found in the C-ring of Saturn appear to be excited by resonances with normal mode oscillations of the planet. The waves are found at locations in the rings where the ratio of orbital to oscillation frequencies is given by m:m+1 where m is a small integer. I suggest here that it is plausible that ring waves may also be launched at second order resonances where the frequency ratio...
The present paper describes parametric studies conducted to define the Uranus entry trade space. Two different arrival opportunities in 2029 and 2043, corresponding to launches in 2021 and 2034, respectively, are considered in the present study. These two launch windows factor in the 84-year orbital period, significant axial tilt, and the wide ring system of Uranus. As part of this study, an improved...
It has been becoming clear that the atmospheres of the young, self‐luminous extrasolar giant planets imaged to date are dusty. Planets with dusty atmospheres may exhibit detectable amounts of linear polarization in the near‐infrared, as has been observed from some field L dwarfs. The asymmetry required in the thermal radiation field to produce polarization may arise either from the rotation‐induced...
Chandrasekhar’s formalisms for the transfer of polarized radiation are used to explain the observed dust scattering polarization of brown dwarfs in the optical band. Model polarization profiles for hot and young directly imaged extrasolar planets are presented with specific prediction of the degree of polarization in the infrared. The model invokes Chandrasekhar’s formalism for the rotation-induced...
Application of a radiative–convective equilibrium model to the thermal structure of Uranus'atmosphere evaluates the role of hazes in the planet's stratospheric energy budget and places a lower limit on the internal energy flux. The model is constrained by Voyager and post-Voyager observations of the vertical aerosol and radiatively active gas profiles. Our baseline model generally reproduces the observed...
Narrowband images of Uranus in the near-infrared from Apache Point Observatory were employed to derive the globally averaged properties of scatterers in the atmosphere in the post-Voyager epoch. In order to best probe different levels of the stratosphere and upper troposphere we measured and modeled the planetary geometric albedo using seven filters ranging from 1.28 to 2.36 μm. Since 1986 there has...
Jupiter was observed in the aftermath of its impact with fragment R of Comet Shoemaker–Levy/9 to search for seismic waves excited by the collision. Observations were made in the 7.8 μm methane emission band with the MIRAC2 camera at the IRTF in an attempt to detect the local perturbation to the equilibrium stratospheric temperature profile induced by the wave. Detection of a jovian seismic wave would...
Schmider et al. (Schmider, F.-X., B. Mosser, and E. Fossat 1991. Astron. Astrophy. 248, 281-291) and Mosser et al. (Mosser, B., D. Mekarnia, J.P. Maillard, J. Gay, D. Gautier, and P. Delache 1993. Astron. Astrophys. 267, 604-622) report detection of Doppler shifts in reflected solar radiation from Jupiter purportedly induced by p-mode oscillations of the planet. We consider the possibility that these...
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