Could Uranus and Neptune form by collisions of planetary embryos?

Clouds of Neptune and Uranus

We present results on the bases and concentrations of methane ice, ammonia ice, ammonium hydrosulfidesolid, water ice, and aqueous-ammonia solution (“droplet”) clouds of Neptune and Uranus, based on an equilibrium cloud condensation model. Due to their similar p-T structures, the model results for Neptune and Uranus are similar. Assuming 30–50× solar enhancement for the condensibles species, as...

MID-INFRARED ETHANE EMISSION ON NEPTUNE AND URANUS Short Title: Ethane on Neptune and Uranus

We report 8to 13-μm spectral observations of Neptune and Uranus from the NASA Infrared Telescope Facility spanning more than a decade. The spectroscopic data indicate a steady increase in Neptune's mean atmospheric 12–μm ethane emission from 1985 to 2003, followed by a slight decrease in 2004. The simplest explanation for the intensity variation is an increase in stratospheric effective tempera...

Limb polarization of Uranus and Neptune ⋆

Aims. We have detected a strong limb polarization for Uranus and Neptune. With spectropolarimetric observations we characterize the spectral dependence of this limb polarization and explore the diagnostic potential for investigating the distribution and properties of the scattering particles. Methods. We present disk resolved spectropolarimetry of Uranus and Neptune covering the wavelength rang...

Photometry of Irregular Satellites of Uranus and Neptune

We present BVR photometric colors of six Uranian and two Neptunian irregular satellites, collected using the Magellan Observatory (Las Campanas, Chile) and the Keck Observatory, (Manua Kea, Hawaii). The colors range from neutral to light red, and like the Jovian and the Saturnian irregulars (Grav et al. 2003a) there is an apparent lack of the extremely red objects found among the Centaurs and K...

Water-ammonia ionic ocean on Uranus and Neptune?