Size and albedo of Kuiper belt object 55636 from a stellar occultation.

The Kuiper belt is a collection of small bodies (Kuiper belt objects, KBOs) that lie beyond the orbit of Neptune and which are believed to have formed contemporaneously with the planets. Their small size and great distance make them difficult to study. KBO 55636 (2002 TX(300)) is a member of the water-ice-rich Haumea KBO collisional family. The Haumea family are among the most highly reflective objects in the Solar System. Dynamical calculations indicate that the collision that created KBO 55636 occurred at least 1 Gyr ago. Here we report observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009 ut. We find that it has a mean radius of 143 +/- 5 km (assuming a circular solution). Allowing for possible elliptical shapes, we find a geometric albedo of in the V photometric band, which establishes that KBO 55636 is smaller than previously thought and that, like its parent body, it is highly reflective. The dynamical age implies either that KBO 55636 has an active resurfacing mechanism, or that fresh water-ice in the outer Solar System can persist for gigayear timescales.

Surface composition of Hyperion.

Hyperion, Saturn's eighth largest icy satellite, is a body of irregular shape in a state of chaotic rotation. The surface is segregated into two distinct units. A spatially dominant high-albedo unit having the strong signature of H2O ice contrasts with a unit that is about a factor of four lower in albedo and is found mostly in the bottoms of cup-like craters. Here we report observations of Hyperion's surface in the ultraviolet and near-infrared spectral regions with two optical remote sensing instruments on the Cassini spacecraft at closest approach during a fly-by on 25-26 September 2005. The close fly-by afforded us the opportunity to obtain separate reflectance spectra of the high- and low-albedo surface components. The low-albedo material has spectral similarities and compositional signatures that link it with the surface of Phoebe and a hemisphere-wide superficial coating on Iapetus.

Reduced cadmium body burden in cadmium-exposed calves fed supplemental zinc.

The objectives of this study were to evaluate the use of practical supplemental dietary zinc to modify the cadmium content in edible bovine tissues and to identify copper interactions with cadmium and zinc. The effect of supplemental zinc (200 or 600 micrograms/g) on the concentrations of cadmium, zinc, and copper in liver, kidney cortex, muscle, and blood of calves fed 50 micrograms/g cadmium for 60 days was evaluated. Blood samples were collected before and eight times after starting to feed cadmium or cadmium plus zinc. Liver, kidney, and muscle samples were collected when calves were slaughtered (baseline, at beginning of experimental feeding; cadmium-fed, at end of 60 days feeding). The cadmium concentrations of all sample types collected were markedly increased by the feeding of cadmium. Feeding 600 micrograms/g supplemental zinc significantly increased the zinc concentrations of liver, kidney cortex, and blood and decreased the cadmium accumulation in these organs as well as muscle. The copper concentrations of muscle or blood were not altered by feeding cadmium with or without zinc but those of liver and kidney cortex were significantly increased by higher dietary levels of zinc and cadmium. The potential use of dietary zinc salts in reducing cadmium body burden in food animals suspected or known to have high cadmium intakes is suggested.

H2O ice in the envelopes of OH/IR stars.

In an attempt to better understand the conditions under which molecules condense onto grains in the envelopes of evolved stars, we have searched for the presence of H2O ice in the circumstellar envelopes of several evolved (OH/IR) stars. The sample of stars observed was selected on the basis of mass-loss rates, luminosities, and outflow velocities in order to cover a range of physical conditions that might affect the amount of ice present in stellar envelopes. Despite the clear presence of H2O ice around other, previously observed, evolved stars, our search in six OH/IR stars has resulted in only one clear detection, in OH 26.5 + 0.6, and the tentative detection in one other, OH 26.4-1.9. We provide column densities or upper limits for the amount of ice that is present on the grains around these stars and explore the possibility that there could be a relationship between M* or M*/L* and the H2O ice column density to explain the observations.