Search Publications
Density of Mars’ South Polar Layered Deposits
Zuber, Maria T.; Asmar, Sami W.; Smrekar, Suzanne E. +6 more
Both poles of Mars are hidden beneath caps of layered ice. We calculated the density of the south polar layered deposits by combining the gravity field obtained from initial results of radio tracking of the Mars Reconnaissance Orbiter with existing surface topography from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor spacecraft and …
Twisting Motions of Sunspot Penumbral Filaments
Kubo, M.; Lites, B. W.; Ichimoto, K. +8 more
The penumbra of a sunspot is composed of numerous thin, radially extended, bright and dark filaments carrying outward gas flows (the Evershed flow). Using high-resolution images obtained by the Solar Optical Telescope aboard the solar physics satellite Hinode, we discovered a number of penumbral bright filaments revealing twisting motions about th…
The Source of Saturn’s G Ring
Porco, Carolyn C.; Hedman, Matthew M.; Burns, Joseph A. +6 more
The origin of Saturn’s narrow G ring has been unclear. We show that it contains a bright arc located 167,495.6 ± 1.3 km from Saturn’s center. This longitudinally localized material is trapped in a 7:6 corotation eccentricity resonance with the satellite Mimas. The cameras aboard the Cassini spacecraft mainly observe small (1 to 10 micrometers) dus…
Io’s Atmospheric Response to Eclipse: UV Aurorae Observations
Stern, S. A.; Saur, J.; Strobel, D. F. +18 more
The New Horizons (NH) spacecraft observed Io’s aurora in eclipse on four occasions during spring 2007. NH Alice ultraviolet spectroscopy and concurrent Hubble Space Telescope ultraviolet imaging in eclipse investigate the relative contribution of volcanoes to Io’s atmosphere and its interaction with Jupiter’s magnetosphere. Auroral brightness and …
Locating the Two Black Holes in NGC 6240
Canalizo, Gabriela; Max, Claire E.; de Vries, Willem H.
Mergers play an important role in galaxy evolution and are key to understanding the correlation between central black hole mass and host-galaxy properties. We used the new technology of adaptive optics at the Keck II telescope to observe NGC 6240, a merger between two disk galaxies. Our high-resolution near-infrared images, combined with radio and…
Fine Thermal Structure of a Coronal Active Region
Golub, Leon; Reale, Fabio; Shimojo, Masumi +9 more
The determination of the fine thermal structure of the solar corona is fundamental to constraining the coronal heating mechanisms. The Hinode X-ray Telescope collected images of the solar corona in different passbands, thus providing temperature diagnostics through energy ratios. By combining different filters to optimize the signal-to-noise ratio…
Jupiter’s Nightside Airglow and Aurora
Parker, Joel Wm.; Stern, S. Alan; Weaver, Harold A. +12 more
Observations of Jupiter’s nightside airglow (nightglow) and aurora obtained during the flyby of the New Horizons spacecraft show an unexpected lack of ultraviolet nightglow emissions, in contrast to the case during the Voyager flybys in 1979. The flux and average energy of precipitating electrons generally decrease with increasing local time acros…
Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data
Drossart, Pierre; Korablev, Oleg; Forget, F. +43 more
Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the ``phyllocian'…
Cassini Observes the Active South Pole of Enceladus
Burns, J. A.; Neukum, G.; Wagner, R. +22 more
Cassini has identified a geologically active province at the south pole of Saturn's moon Enceladus. In images acquired by the Imaging Science Subsystem (ISS), this region is circumscribed by a chain of folded ridges and troughs at ~55°S latitude. The terrain southward of this boundary is distinguished by its albedo and color contrasts, elevated te…
Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure
Ip, Wing-Huen; McNutt, Ralph L.; Waite, J. Hunter +11 more
The Cassini spacecraft passed within 168.2 kilometers of the surface above the southern hemisphere at 19:55:22 universal time coordinated on 14 July 2005 during its closest approach to Enceladus. Before and after this time, a substantial atmospheric plume and coma were observed, detectable in the Ion and Neutral Mass Spectrometer (INMS) data set o…