Search Publications
Seasonal photometric variability of Titan, 1972-2006
Lockwood, G. W.; Thompson, D. T.
Measurements at Lowell Observatory of Titan in the b (472 nm) and y (551 nm) filters of the Strömgren photometric system at thirty four consecutive apparitions (282 nights) from 1971/72 to 2006 show a 10% sinusoidal variation that lags seasonal extremes by about 1/8 of a Titan year. The seasonal variations are asymmetric: the autumn lightcurve max…
Organizing some very tenuous things: Resonant structures in Saturn's faint rings
Hedman, M. M.; Burns, J. A.; Porco, C. C. +1 more
Images of the dusty rings obtained by the Cassini spacecraft in late 2006 and early 2007 reveal unusual structures composed of alternating canted bright and dark streaks in the outer G ring (∼170,000 km from Saturn center), the inner Roche Division (∼138,000 km) and the middle D ring (70,000-73,000 km). The morphology, locations and pattern speeds…
Determining a tilt in Titan’s north-south albedo asymmetry from Cassini images
West, Robert A.; Nixon, Conor A.; Achterberg, Richard K. +4 more
Analysis of Titan's hemispheric brightness asymmetry from mapped Cassini images reveals an axis of symmetry that is tilted with respect to the rotational axis of the solid body. Twenty images taken from 2004 through 2007 show a mean axial offset of 3.8 ± 0.9° relative to the solid body's pole, directed 79 ± 24° to the west of the sub-solar longitu…
Structure of self-gravity wakes in Saturn's A ring as measured by Cassini CIRS
Leyrat, C.; Ferrari, C.; Spilker, L. +3 more
The CIRS infrared spectrometer onboard the Cassini spacecraft has scanned Saturn's A ring azimuthally from several viewing angles since its orbit insertion in 2004. A quadrupolar asymmetry has been detected in this ring at spacecraft elevations ranging between 16° to 37°. Its fractional amplitude decreases from 22% to 8% from 20° to 37° elevations…
A multilayer model for thermal infrared emission of Saturn's rings: Basic formulation and implications for Earth-based observations
Ohtsuki, Keiji; Salo, Heikki; Morishima, Ryuji
We present our new model for the thermal infrared emission of Saturn's rings based on a multilayer approximation. In our model, (1) the equation of classical radiative transfer is solved directly for both visible and infrared light, (2) the vertical heterogeneity of spin frequencies of ring particles is taken into account, and (3) the heat transpo…
Vertical shears in Saturn's eastward jets at cloud level
Hueso, R.; Rojas, J. F.; Pérez-Hoyos, S. +2 more
We have measured the vertical shear of the zonal winds in the cloud-haze upper layer of Saturn using Cassini ISS images obtained in the filters MT2 (753 nm methane absorption band, sensitive to the upper haze) and CB2 (adjacent continuum, sensitive to the lower cloud). Our radiative transfer models indicate that at the eastward jet peaks these fil…
OMEGA/Mars Express: South Pole Region, water vapor daily variability
Langevin, Y.; Forget, F.; Maltagliati, L. +8 more
Polar regions on Mars are the most suitable places to observe water vapor daily variability because in any observation crossing the Pole we can observe very different local time and because the poles are considered to be the main permanent and seasonal water reservoir of the planet. We report on a daily variability of water vapor in the South Pole…
Physical collisions of moonlets and clumps with the Saturn's F-ring core
Charnoz, Sébastien
Since 2004, observations of Saturn's F-ring have revealed that the ring's core is surrounded by structures with radial scales of hundreds of kilometers, called "spirals" and "jets." Gravitational scattering by nearby moons was suggested as a potential production mechanism; however, it remained doubtful because a population of Prometheus-mass moons…
Small-scale composition and haze layering in Titan’s polar vortex
Irwin, P. G. J.; Teanby, N. A.; de Kok, R.
Fine scale layering of haze and composition in Titan's stratosphere and mesosphere was investigated using visible/UV images from Cassini's Imaging Science Sub-system (ISS) and IR spectra from Cassini's Composite Infra-Red Spectrometer (CIRS). Both ISS and CIRS independently show fine layered structures in haze and composition, respectively, in the…
Titan at 3 microns: Newly identified spectral features and an improved analysis of haze opacity
Kim, Sang Joon; Geballe, Thomas R.; Courtin, Régis +3 more
We have reanalyzed the high-resolution spectrum of Titan between 2.87 and 3.12 µm observed with NIRSPEC/Keck II on 2001 Nov. 21 in southern summer, using updated CH 3D and C 2H 6 line-by-line models. From new synthetic spectra, we identify all but a few of the previously unidentified significant absorption sp…