Mutual Potential of Homogeneous Polyhedra

The mutual gravitational potential between a pair of homogeneous polyhedra is expressed using an infinite series. The nested volume integrals are evaluated analytically and result in simple tensor expressions containing no special functions. However, complexity increases as O(6 ⁿ ), where n is the term degree. An alternate formulation due to Liebenthal is also presented.     

Further finds of the Derrick Peak meteorite,Transantarctic Mountains,and implications for terrestrial age

Abstract— Nine additional iron meteorite fragments weighing a total of 72 kg were recovered from the Derrick Peak area by a Canterbury Museum geological party in late 1988. One iron was located in the Onnum Valley, 6 km south of the previous finds. Geochemical analysis indicates that all irons belong to a single meteorite shower, greatly increasing the known extent of the fall zone. Kamp and Lowe (1982) have previously estimated the terrestrial age of the meteorite from glacial geological evidence. The location of the 1988 finds supports Kamp and Lowe's interpretation that the meteorites lie in situ, but recent revisions of the chronology of Cenozoic glacial history of the region reduce the interpreted terrestrial age. An age of between Oxygen Isotope stages 6 and 2 is probable (190–125 to 35–12 ka BP). This conflicts with a terrestrial age estimate of 1.0 ± 0.1 Ma BP from cosmogenic radionuclides.     

Silicon carbide and the infrared excess of carbon stars

This paper reports laboratory investigations on the absorption spectrum of SiC particles in the 10 μm region. The particles had a mean diameter of 0.31 μm. Our experimental results indicate that a large part of the infrared excess observed in carbon stars may be caused by SiC.     

Polarimetric and photometric observations of the star m cephei

The results of photometric and polarimetric observations of the star Μ Cep at Byurakan Observatory are presented. Some interesting correlations between the parameters of the star’s brightness variation and the degree of polarization of the light are obtained. It is suggested that the recorded rapid changes in the degree of polarization may result from Μ Cep being a double star. Translated from Astrofizika, Vol. 43, No. 2, pp. 219-228, April–June, 2000.     

Trace constituents of Europa's atmosphere

Europa is bombarded by intense radiation that erodes the surface, launching molecules into a thin “atmosphere” representative of surface composition. In addition to atoms and molecules created in the mostly water ice surface such as H₂O, O₂, H₂, the atmosphere is known to have species representative of trace surface materials. These trace species are carried off with the 10-10⁴ H₂O molecules ejected by each energetic heavy ion, a process we have simulated using molecular dynamics. Using the results of those simulations, we found that a neutral mass spectrometer orbiting ∼100 km above the surface could detect species with surface concentrations above ∼0.03%. We have also modeled the atmospheric spatial structure of the volatile species CO₂ and SO₂ under a variety of assumptions. Detections of these species with moderate time and space resolution would allow us to constrain surface composition, chemistry and to study space weathering processes.