Search Publications
A planetary system as the origin of structure in Fomalhaut's dust belt
Kalas, Paul; Graham, James R.; Clampin, Mark
The Sun and >15per cent of nearby stars are surrounded by dusty disks that must be collisionally replenished by asteroids and comets, as the dust would otherwise be depleted on timescales <107years (ref. 1). Theoretical studies show that the structure of a dusty disk can be modified by the gravitational influence of planets, but t…
Imaging of Titan from the Cassini spacecraft
Dones, Luke; Porco, Carolyn C.; McEwen, Alfred +33 more
Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of …
Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars
Jaumann, R.; Head, J. W.; Neukum, G. +11 more
Images from the Mars Express HRSC (High-Resolution Stereo Camera) of debris aprons at the base of massifs in eastern Hellas reveal numerous concentrically ridged lobate and pitted features and related evidence of extremely ice-rich glacier-like viscous flow and sublimation. Together with new evidence for recent ice-rich rock glaciers at the base o…
An upper limit to the masses of stars
Figer, Donald F.
There is no accepted upper mass limit for stars. Such a basic quantity eludes both theory and observation, because of an imperfect understanding of the star-formation process and because of incompleteness in surveying the Galaxy. The Arches cluster is ideal for investigating such limits, being large enough to expect stars at least as massive as ~5…
Differentiation of the asteroid Ceres as revealed by its shape
Russell, C. T.; Stern, S. A.; Young, E. F. +4 more
The accretion of bodies in the asteroid belt was halted nearly 4.6billion years ago by the gravitational influence of the newly formed giant planet Jupiter. The asteroid belt therefore preserves a record of both this earliest epoch of Solar System formation and variation of conditions within the solar nebula. Spectral features in reflected sunligh…
The mass of the missing baryons in the X-ray forest of the warm-hot intergalactic medium
Elvis, Martin; Zezas, Andreas; Marshall, Herman +7 more
Recent cosmological measurements indicate that baryons comprise about four per cent of the total mass-energy density of the Universe, which is in accord with the predictions arising from studies of the production of the lightest elements. It is also in agreement with the actual number of baryons detected at early times (redshifts z > 2). Close …
Release of volatiles from a possible cryovolcano from near-infrared imaging of Titan
Rodriguez, S.; Sotin, C.; Brown, R. H. +23 more
Titan is the only satellite in our Solar System with a dense atmosphere. The surface pressure is 1.5bar (ref. 1) and, similar to the Earth, N2 is the main component of the atmosphere. Methane is the second most important component, but it is photodissociated on a timescale of 107years (ref. 3). This short timescale has led to…
Discovery of an aurora on Mars
Bertaux, Jean-Loup; Leblanc, François; Korablev, Oleg +5 more
In the high-latitude regions of Earth, aurorae are the often-spectacular visual manifestation of the interaction between electrically charged particles (electrons, protons or ions) with the neutral upper atmosphere, as they precipitate along magnetic field lines. More generally, auroral emissions in planetary atmospheres ``are those that result fr…
Complex organic matter in Titan's atmospheric aerosols from in situ pyrolysis and analysis
Steller, M.; Atreya, S. K.; Owen, T. +19 more
Aerosols in Titan's atmosphere play an important role in determining its thermal structure. They also serve as sinks for organic vapours and can act as condensation nuclei for the formation of clouds, where the condensation efficiency will depend on the chemical composition of the aerosols. So far, however, no direct information has been available…
An overview of the descent and landing of the Huygens probe on Titan
Lebreton, Jean-Pierre; Witasse, Olivier; Matson, Dennis L. +9 more
Titan, Saturn's largest moon, is the only Solar System planetary body other than Earth with a thick nitrogen atmosphere. The Voyager spacecraft confirmed that methane was the second-most abundant atmospheric constituent in Titan's atmosphere, and revealed a rich organic chemistry, but its cameras could not see through the thick organic haze. After…