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We used the InfraRed Imaging Spectrometer (IRIS) on the Anglo-Australian Telescope to monitor the July 1994 impacts of Comet Shoemaker-Levy 9 with Jupiter. Spectral image cubes were obtained for the impacts of fragments C, D, G, K, R, and W. These data provide time sequences of spatially resolved spectra in K-band (1.98 to 2.40 μm), with a spectral resolution of 300 (λ/Δλ) and a spatial sampling of...
In May, August, and November 1995, Hubble Space Telescope (HST) observations during Saturn's ring-plane crossings allowed us to view saturnian satellites normally hidden to Earth-based observers in the glare of the rings. New measurements of Janus, Epimetheus, Prometheus, and Pandora have been combined to form revised orbital solutions using all three HST data sets. These measurements and orbit fits...
We present V and R photometry of 16 Kuiper belt objects (KBOs) from the 3.6-m Telescopio Nazionale Galileo and the Complejo Astronomico El Leoncito 2.1-m telescope. We find a wide dispersion in the (V-R) colors of the objects, indicating nonuniform surface properties. If we assume near constant albedos, there does not appear to be a general trend of redness with size, but the color range for classical...
Recent observations of the size-frequency distribution of zodiacal cloud particles obtained from the cratering record on the LDEF satellite are the latest evidence for a significant large particle population (100-μm diameter or greater) near 1 AU. Our previous modeling of the Solar System dust bands, features of the zodiacal cloud associated with the comminution of Hirayama family asteroids, has been...
We present observations of the Centaur 5145 Pholus from January 2000 to August 2000. A rotational lightcurve was assembled from both V and R measurements, confirming previous period determinations of 0.416 day but exhibiting an amplitude over twice as high as previously measured. This lightcurve was then used in conjunction with previously published lightcurves to solve for a north pole position of...
Photometrically calibrated grism spectra of Saturn in the H-(1.45-1.80 μm) and K-band (1.95-2.50 μm) are presented. The spectra were obtained with the 200-inch Hale telescope at Palomar mountain three days after the ring plane crossing of August 10, 1995. By inversion of the spectra, the vertical distribution of the scattering density is obtained as a function of latitude along the central meridian,...
The results of 16 new 3D N-body simulations of the final stage of the formation of the terrestrial planets are presented. These N-body integrations begin with 150-160 lunar-to-Mars size planetary embryos, with semi-major axes 0.3<a<2.0 AU, and include perturbations from Jupiter and Saturn. Two initial mass distributions are examined: approximately uniform masses, and a bimodal distribution with...
We present a five-year study of the temporal stability of Jupiter's zonal wind velocity profile at cloud level based on Hubble Space Telescope images obtained from 1995 to 2000. We used the correlation of east-west albedo scans in pairs of images separated by one jovian rotation to retrieve the zonal winds. The resolution in the HST images ranged from 140 to 190 km pixel -1 . Independent...
The structure of the Jovian stratosphere at the Galileo probe entry site is investigated through calculations of radiative heating rates based on measurements of the temperature profile, composition, and aerosol distribution. From analysis of mid-IR observations of Jupiter, we determine a C 2 H 2 mole fraction of 1.1-4.3x10 -6 at 0.01 mbar, and a C 2 H 6 ...
The Nysa-Polana dynamical family is one of the most complex groupings identified in the asteroid main belt. It has a generally twofold structure and is located in a region of the belt showing an unusual abundance of the fairly rare F-type taxonomic class. We present here new spectra of 22 family members, observed at ESO (European Southern Observatory) and at CASLEO (Complejo Astronomico El Leoncito,...
The J0-ingress radio occultation of the Galileo orbiter by Jupiter exhibits a system of well-defined, regularly spaced electron layers in the altitude range where the presence of gravity waves have been previously inferred. Based on the terrestrial analog of sporadic E and spread F ionospheric layers, we argue that the observed layers are a result of dynamical processes rather than chemistry. We consider...
Diagrams, color index C(0.95/0.75 μm) versus albedo A(0.75 μm), are used to estimate composition and maturity degree of the lunar regolith. We simulate maturation curves on the diagrams with the model (Shkuratov, Yu. G., L. V. Starukhina, H. Hoffmann, and G. Arnold 1999. Icarus137, 235-246). In simulation, decrease of characteristic particle size as well as increase of concentration of reduced iron...
The water production rates of comets 2P/Encke and 81P/Wild 2 during their 1997 apparitions have been estimated from Lyman-α observations of the SWAN instrument and compared to previously published values. 2P/Encke was detected 28 times from few days preperihelion to 1.4 AU postperihelion with a perihelion water production rate Q H2O of 2x10 28 s -1 . This...
In order to investigate seasonal variations of the composition of Titan's low stratosphere, we developed a two-dimensional (latitude-altitude) photochemical and transport model. Large-scale advection, hidden in the vertical eddy diffusion for one-dimensional models, is accounted for explicitly. Atmospheric dynamics is prescribed using results of independent numerical simulations of the atmospheric...
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