Search Publications
Probing the Faintest Stars in a Globular Star Cluster
Anderson, Jay; Rich, R. Michael; Stetson, Peter B. +10 more
NGC 6397 is the second closest globular star cluster to the Sun. Using 5 days of time on the Hubble Space Telescope, we have constructed an ultradeep color-magnitude diagram for this cluster. We see a clear truncation in each of its two major stellar sequences. Faint red main-sequence stars run out well above our observational limit and near to th…
Saturn's Spokes: Lost and Found
Porco, C. C.; Horányi, M.; Mitchell, C. J. +1 more
The spokes are intermittently appearing radial markings in Saturn's B ring that are believed to form when micrometer-sized dust particles are levitated above the ring by electrostatic forces. First observed by the Voyagers, the spokes disappeared from October 1998 until September 2005, when the Cassini spacecraft saw them reappear. The trajectorie…
Enceladus' Varying Imprint on the Magnetosphere of Saturn
Krupp, N.; Woch, J.; Dougherty, M. K. +6 more
The bombardment of Saturn's moon Enceladus by >20-kiloelectron volt magnetospheric particles causes particle flux depletions in regions magnetically connected to its orbit. Irrespective of magnetospheric activity, proton depletions are persistent, whereas electron depletions are quickly erased by magnetospheric processes. Observations of these …
Enceladus: Cosmic Gymnast, Volatile Miniworld
Kargel, Jeffrey S.
The exploration of Saturn by the Cassini/Huygens mission has yielded a rich collection of data about the planet and its rings and moons, in particular its small satellite Enceladus and giant satellite Titan. Once believed too small to be active, Enceladus has been found to be one of the most geologically dynamic objects in the solar system. Among …
New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring
de Pater, Imke; Showalter, Mark R.; Hammel, Heidi B. +1 more
We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/20…
Does Enceladus Govern Magnetospheric Dynamics at Saturn?
Kivelson, Margaret Galland
Instruments on the Cassini spacecraft reveal that a heat source within Saturn's moon Enceladus powers a great plume of water ice particles and dust grains, a geyser that jets outward from the south polar regions and most likely serves as the dominant source of Saturn's E ring. The interaction of flowing magnetospheric plasma with the plume modifie…