Dust properties of [WCL] CSPNS

The rather rare class of central stars of planetary nebulae thatshow Wolf-Rayet spectra have been a subject of great interest,particularly in the infrared, since their discovery in the late1960s. I will focus on further peculiarities found within thepast 1-2 years with the advent of infrared spectroscopy fromISO. Notably, these stars simultaneously betray the presenceof regions of carbon-rich and oxygen-rich dust chemistry. Icompare and contrast complete ISO spectra from 2 to 200 micronsof a small sample of [WC9] to [WC11] central stars.     

Boundary layer ion composition at Jupiter during the inbound pass of the Ulysses flyby

During the inbound segment of the Ulysses flyby of Jupiter, there were multiple incursions into the dawnside low-latitude boundary layer, as identified by Bame et al. (Science257, 1539–1542, 1992) using plasma electron data. In the present study, ion composition and spectral measurements provide independent collaborative evidence for the existence of distinct boundary layer regions. Measurements are taken in the energy-per-charge range of 0.6–60 keV/e and involve mass as well as mass-per-charge identification by the Ulysses/SWICS experiment. Ion species of Jovian magnetospheric origin (including O⁺, O²⁺, S²⁺, S³⁺) and sheath origin (including He²⁺ and high charge state CNO) have been directly identified for the first time in the Jovian magnetospheric boundary layer. Protons of probably mixed origin and He⁺ of possibly sheath (ultimately interstellar pickup) origin were also observed in the boundary layer. Sheath-like ions are observed throughout the boundary layer; however, the Jovian ions are depleted or absent for portions of two boundary layer cases studied. Ions of solar wind origin are observed within the outer magnetosphere. and ions of magnetospheric origin are found within the sheath, indicating that transport across the magnetopause boundary can work both ways, at least under some conditions. Although their source cannot be uniquely identified, the proton energy spectrum in the boundary layer suggests a sheath origin for the lower energy protons.     

Observing Magnetic Fields in Star-Forming Regions

Magnetic field strengths and directions can be estimated using many different observational techniques that span a wide range of wavelengths. Each observational method favours different regimes of scale size, density and other physical conditions. The available techniques and their ranges of applicability are briefly described and the current status of observations is reviewed, with particular emphasis on high-resolution observations of star-forming regions.     

A MERLIN survey of 4.7-GHz excited OH masers in star-forming regions

Phase-referenced observations of 13 star-forming regions in the  ²Π_1/2, J = 1/2  transition of rotationally excited OH at 4765 MHz have been carried out using MERLIN. Two of the regions were also observed at 4750 MHz and one at 4660 MHz. There were 10 maser detections at 4765 MHz and three non-detections. There were no detections at 4750 and 4660 MHz. The 4765-MHz masers have brightness temperatures of  ∼10⁷ K  at MERLIN resolution (∼50 mas). Several cases of 4765-MHz masers overlapping in position and velocity with 1720- and 1665-MHz masers are reported. There are also isolated 4765-MHz masers with peak flux densities ≥30 times that of any ground-state counterpart. Most of the 4.7-GHz maser spots are unresolved at 50-mas angular resolution, but in four of the nearest sources the maser spots are resolved, indicating a characteristic size for 4765-MHz maser regions of ∼100 au. In W3(OH) we discovered that 20 per cent of the 4765-MHz emission comes from a narrow low-brightness filament that stretches north–south for ∼1.0 arcec (∼2200 au) between two previously known 4765-MHz maser spots. The filament appears in projection against the H  ii region and has a brightness temperature of  ∼4 × 10⁵ K  . There are matching absorption features in mainline transitions of highly excited OH. The filament may trace a shock front in a rotating disc.     

The low-eccentricity earth satellite orbit at the critical inclination

A solution to the orbital motion of an Earth satellite at the critical inclination and with near-zero eccentricity is developed by the von Zeipel method to the first order in the eccentricity, and to the first order in the higher gravitational harmonics, using elements which do not degenerate at zero eccentricity.