Search Publications
The Presence of Two Distinct Red Giant Branches in the Globular Cluster NGC 1851
Joo, Seok-Joo; Han, Sang-Il; Kim, Hak-Sub +4 more
There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant branches (RGBs) having different heavy elemental abundances as observed in ω Centauri is hitherto lacking, although spread…
Titan's Surface Brightness Temperatures
Pearl, J. C.; Flasar, F. M.; Coustenis, A. +17 more
Radiance from the surface of Titan can be detected from space through a spectral window of low opacity in the thermal infrared at 19 µm (530 cm-1). By combining Composite Infrared Spectrometer observations from Cassini's first four years, we have mapped the latitude distribution of zonally averaged surface brightness temperatures.…
Spectral Observations of the Enceladus Plume with Cassini-Vims
Brown, R. H.; Buratti, B. J.; Clark, R. N. +3 more
On 2005 November 27 (day 331), the Visual and Infrared Mapping Spectrometer instrument onboard the Cassini spacecraft obtained high signal-to-noise, spatially resolved measurements of Enceladus' particle plume. These data are processed to obtain spectra of the plume at a range of altitudes between 50 and 300 km from the surface. These spectra show…
Characterization of Clouds in Titan's Tropical Atmosphere
Sotin, Christophe; Le Mouélic, Stéphane; Rodriguez, Sebastien +7 more
Images of Titan's clouds, possible over the past 10 years, indicate primarily discrete convective methane clouds near the south and north poles and an immense stratiform cloud, likely composed of ethane, around the north pole. Here we present spectral images from Cassini's Visual Mapping Infrared Spectrometer that reveal the increasing presence of…
Formation Conditions of Enceladus and Origin of Its Methane Reservoir
Lunine, J. I.; Waite, J. H.; Magee, B. +5 more
We describe a formation scenario of Enceladus constrained by the deuterium-to-hydrogen ratio (D/H) in the gas plumes as measured by the Cassini Ion and Neutral Mass Spectrometer. We propose that, similarly to Titan, Enceladus formed from icy planetesimals that were partly devolatilized during their migration within the Kronian subnebula. In our sc…
Discovery of Fog at the South Pole of Titan
Brown, M. E.; Chen, C.; Ádámkovics, M. +1 more
While Saturn's moon Titan appears to support an active methane hydrological cycle, no direct evidence for surface-atmosphere exchange has yet appeared. The indirect evidence, while compelling, could be misleading. It is possible, for example, that the identified lake features could be filled with ethane, an involatile long-term residue of atmosphe…
A Crossed Molecular Beams Study on the Formation of the Exotic Cyanoethynyl Radical in Titan's Atmosphere
Yung, Y. L.; Gu, X.; Kaiser, R. I. +5 more
The reaction of the dicarbon molecule (C2) in its 1Σg + electronic ground state with hydrogen cyanide HCN(X1Σ+) is investigated in a crossed molecular beam setup to untangle the formation of the cyanoethynyl radical CCCN(X2Σ+) in hydrocarbon-rich atmospheres of…
Is the 3.5 µm Infrared Feature on Enceladus Due to Hydrogen Peroxide?
Loeffler, M. J.; Baragiola, R. A.
We use new and previously published measurements from our laboratory to examine the assignment of a 3.5 µm feature in the infrared spectrum of Enceladus. The spectral feature, taken with Cassini's VIMS Spectrometer, has recently been interpreted as an absorption band from hydrogen peroxide on the surface. Such identification is important bec…