Search Publications
On a systematic spectral variation of energetic ions in the Jovian outer magnetosphere: HI-SCALE/Ulysses observations
Sarris, E. T.; Anagnostopoulos, G. C.; Marhavilas, P. K.
An important finding of Ulysses flyby of Jupiter is the discovery of a large-scale energetic particle layer adjacent to the magnetopause. Previous studies discussed the particle flux and the anisotropy characteristics of this layer. This study examines the spectral characteristics of the large-scale magnetopause boundary layer of energetic particl…
A population of extreme mid-to-near-infrared sources: Obscured AGN and dusty starbursts
Vaccari, M.; Väisänen, P.; Johansson, P. H.
We present a sample of mid-infrared detected sources from the European Large Area ISO Survey (ELAIS) regions characterised by strong mid-IR radiation with faint near-IR and optical counterparts. These extreme mid-to-near-IR objects (EMNOs) are defined here by a flux ratio of fν (15 µm) / fν (2.2 µm) > 25. This …
Development of a micro-balance system for dust and water vapour detection in the Mars atmosphere
Colangeli, L.; Palumbo, P.; Palomba, E. +2 more
Quartz crystal piezoelectric sensors are suitable for deposition analyses that need very high sensitivity. Due to the wide working ranges and high performances, micro-balances can measure the mass settling in average Mars conditions during a period of months before saturation is reached. This ensures a proper use for short and long term water and …
Simulation and analysis of the revised Huygens probe entry and descent trajectory and radio link modelling
Lebreton, J. -P.; Kazeminejad, B.; Pérez-Ayúcar, M. +7 more
The Cassini spacecraft will arrive at Saturn in 2004 carrying the Huygens probe. The beginning of the Cassini tour at Saturn has been redesigned to achieve a different relative orbiter/probe geometry in order to compensate for the probe relay receiver design flaw that was discovered during tests in February 2000. This paper presents a numerical si…
Searching for Variability in the Globular Cluster Messier 4
Ibata, Rodrigo A.; Rich, R. Michael; Gibson, Brad K. +11 more
Time-series data taken with the Hubble Space Telescope of a field six core radii (~5') from the center of the globular cluster Messier 4, and covering a period of about 10 weeks in early 2001, have been analyzed in search of variable objects. Various criteria were employed to select candidate variable stars. Period searches were performed on the s…
Secular Trends in the Mean Longitudes of Planets Derived from Optical Observations
Kolesnik, Yuri B.; Masreliez, C. Johan
About 240,000 worldwide optical observations of the Sun, Mercury, and Venus, accumulated during the entire era of classical astrometry from James Bradley up to the present, are used to analyze the secular longitude variations of the innermost planets. A reduction method relating historical planetary observations to the Hipparcos reference frame is…
Collisions among Clouds inside Dusty Tori in Active Galactic Nuclei:Observational Consequences
Wang, Jian-Min
A geometrically thick dusty torus in NGC 1068 has been unambiguously resolved by an infrared interferometry telescope. This implies that clouds composing the dusty torus are undergoing supersonic collisions with each other. We show that the collisions form strong nonrelativistic shocks, which accelerate populations of relativistic electrons. The t…
HST/STIS observations of sdBV stars: testing diffusion and pulsation theory
Heber, U.; Chayer, P.; Fontaine, G. +3 more
We present the initial results of an abundance analysis of echelle UV spectra of five hot subdwarf B (sdB) stars. These stars have been identified as core helium burning objects on the extreme Horizontal Branch. Around 5% of sdBs show short-period acoustic-mode oscillations. Models predict that these oscillations are due to an opacity bump caused …
60 Milliarcsecond Near-Infrared Imaging of 3C 273 with Altair and Gemini
Hutchings, J. B.; Rigaut, F.; Veran, J. -P. +1 more
We report data from the commissioning run of the Altair adaptive optics instrument on Gemini North. The bright QSO 3C 273 was observed at f/32 in the H and J bands, and at f/14 with J band, using the QSO itself as guide star. Resolution of approximately 60 mas full width at half-maximum (FWHM) was achieved in H band. The data and point-spread func…
Mid-Infrared Observations of van Maanen 2: No Substellar Companion
Becklin, E. E.; Farihi, J.; Macintosh, B. A.
The results of a comprehensive infrared imaging search for the putative 0.06 Msolar astrometric companion to the 4.4 pc white dwarf van Mannen 2 are reported. Adaptive optics images acquired at 3.8 µm reveal a diffraction-limited core of 0.09" and no direct evidence of a secondary. Models predict that at 5 Gyr, a 50MJ b…