SOS: the visible spectroscopic survey of 820 asteroids

We present the results of a visible spectroscopic survey of 820 asteroids carried on between November 1996 and September 2001 at the 1.52 m telescope at ESO (La Silla). The instrumental set-up allowed an useful spectral range of about 4900 Å<λ<9200 Å. The global spatial distribution of the observed asteroids covers quite well all the region between 2.2 and 3.3 AU though some concentrations are apparent. These are due to the fact that several sub-sets of asteroids, such as families and groups, have been selected and studied during the development of the survey. The observed asteroids have been classified using the Tholen and the Bus taxonomies which, in general, agree quite well.     

Model of the W3(OH) Environment Based on Data for Both Maser and “Quasi-Thermal” Methanol Lines

In studies of the environment of massive young stellar objects, recent progress in both observations and theory allows a unified treatment of data for maser and quasi-thermal lines. Interferometric maser images provide information on the distribution and kinematics of masing gas on small spatial scales. Observations of multiple masing transitions provide constraints on the physical parameters.Interferometric data on quasi-thermal molecular lines permits an investigation of the overall distribution and kinematics of the molecular gas in the vicinity of young stellar objects, including those which are deeply embedded. Using multiple transitions of different molecules, one can obtain good constraints on the physical and chemical parameters. Combining these data enables the construction of unified models, which take into account spatial scales differing by orders of magnitude.Here, we present such a combined analysis of the environment around the ultracompact HII region in W3(OH). This includes the structure of the methanol masing region, physical structure of the near vicinity of W3(OH), detection of new masers in the large-scale shock front and embedded sources in the vicinity of the TW young stellar object.     

Observations with the Visual and Infrared Mapping Spectrometer (VIMS) during Cassini's flyby of Jupiter

The Cassini Visual and Infrared Mapping Spectrometer (VIMS) is an imaging spectrometer covering the wavelength range 0.3-5.2 μm in 352 spectral channels, with a nominal instantaneous field of view of 0.5 mrad. The Cassini flyby of Jupiter represented a unique opportunity to accomplish two important goals: scientific observations of the jovian system and functional tests of the VIMS instrument under conditions similar to those expected to obtain during Cassini's 4-year tour of the saturnian system. Results acquired over a complete range of visual to near-infrared wavelengths from 0.3 to 5.2 μm are presented. First detections include methane fluorescence on Jupiter, a surprisingly high opposition surge on Europa, the first visual-near-IR spectra of Himalia and Jupiter's optically-thin ring system, and the first near-infrared observations of the rings over an extensive range of phase angles (0-120°). Similarities in the center-to-limb profiles of H⁺₃ and CH₄ emissions indicate that the H⁺₃ ionospheric density is solar-controlled outside of the auroral regions. The existence of jovian NH₃ absorption at 0.93 μm is confirmed. Himalia has a slightly reddish spectrum, an apparent absorption near 3 μm, and a geometric albedo of 0.06±0.01 at 2.2 μm (assuming an 85-km radius). If the 3-μm feature in Himalia's spectrum is eventually confirmed, it would be suggestive of the presence of water in some form, either free, bound, or incorporated in layer-lattice silicates. Finally, a mean ring-particle radius of 10 μm is found to be consistent with Mie-scattering models fit to VIMS near-infrared observations acquired over 0-120° phase angle.     

Simulating colour variations in pulsating sdB stars

After briefly recalling basic facts about the metallicity gradients inspiral galaxies, we summarize two recent N-body gas-dynamical modelsthat implement a non-instantaneous gas recycling and point our their potential for an improved treatment of the chemical evolution ingalactic disks.     

Close binary EHB stars from SPY

We present the results of a radial velocity (RV) survey of 46 subdwarf B (sdB) and 23 helium-rich subdwarf O (He-sdO) stars. We detected 18 (39%) new sdB binary systems, but only one (4%) He-sdO binary. Orbital parameters of nine sdB and sdO binaries, derived from follow-up spectroscopy, are presented. Our results are compared with evolutionary scenarios and previous observational investigations.     

NIGHTGLOW: an instrument to measure the Earth’s nighttime ultraviolet glow—results from the first engineering flight

We have designed and built an instrument to measure and monitor the “nightglow” of the Earth’s atmosphere in the near ultraviolet (NUV). In this paper we describe the design of this instrument, called NIGHTGLOW. NIGHTGLOW is designed to be flown from a high altitude research balloon, and circumnavigate the globe. NIGHTGLOW is a NASA, University of Utah, and New Mexico State University project. A test flight took place from Palestine, Texas on July 5, 2000, lasting about 8 h. The instrument performed well and landed safely in Stiles, Texas with little damage. The resulting measurements of the NUV nightglow are compared with previous measurements from sounding rockets and balloons.