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Understanding some moving groups in terms of a global spiral shock.
Figueras, F.; Torra, J.; Comeron, F.
We present a schematic model to interpret the kinematics of some major moving groups in the solar neighbourhood. The origin of these groups is assumed to lie in large scale spiral shocks which may be responsible for the spiral arms in the galactic disk, which provide the initial conditions in the velocities of stars formed as a consequence of them…
Observation of interplanetary particles in a corotating interaction region and of energetic water group ions from comet Grigg-Skjellerup
Coates, A. J.; Neubauer, F. M.; Daly, P. W. +2 more
During the flyby of the Giotto S/C with comet Grigg-Skjellerup (G-S) (9-11 July 1992) energetic particles ( EH 2O > 60 keV, Ep > 30 keV, Eα > 3.5 MeV), magnetic fields and plasma ions were measured by three different detectors on board Giotto. The flyby period was characterized by high magnetic field …
Optical emission in the radio lobes of Cygnus A.
Nilsson, K.; Jones, L. R.; Lehto, H. J. +2 more
Deep optical imaging and spectroscopy of stellar objects in the radio lobes of Cygnus A have been carried out. Brighter optical objects close to the radio hotspots are either confirmed or suspected Galactic stars. Very faint optical emission is found coinciding with hotspot D (R~23.1) and hotspot B (V~25.4). The implications of these observations …
Opportunities for Magnetospheric Research with Coordinated Cluster and Ground-Based Observations
Lockwood, M.; Opgenoorth, H. J.
HST observations of IP Pegasi in quiescence: the pre-eclipse spectrum
Eracleous, Michael; Szkody, Paula; Horne, Keith +5 more
We present time-resolved HST ultraviolet (UV) spectroscopy and ground-based optical photometry of the dwarf nova IP Pegasi in a quiescent state. The observations were obtained prior to an eclipse, when the bright spot caused by the impact of the accretion stream with the edge of the disc dominates the light output. The optical light curve is fairl…
ISO LWS Observations of Evolved Stars and Nebulae
Barlow, M. J.
The Hipparcos distances of open clusters and their implication on the local variations of the ΔY/ΔZ ratio.
Zinnecker, H.; Schilbach, E.; Efremov, Yu. N.
Arguments are collected to demonstrate that recent Hipparcos results on the distances of open clusters are in agreement with previous estimates in the Russian literature which have pointed to a shorter distance scale. Evidence of the absence of a universal correlation between helium and metal abundances is given. It is suggested that violations of…
Latitudinal structure of the heliospheric current sheet and corotating streams measured by WIND and ULYSSES
Tsurutani, B. T.; Steinberg, J. T.; Goldstein, B. E. +5 more
All heliospheric current sheet (HCS) crossings and corotating solar wind streams detected by both WIND and Ulysses have been identified. These measurements were made when Ulysses was in its fast latitudinal scan (at a heliocentric radial distance of ∼1.4 AU) and WIND was in the ecliptic plane near the Earth. Instantaneous solar wind velocities are…
Multiwavelength studies of β Cephei stars: δ Ceti.
Cugier, H.; Nowak, D.
We discuss diagnostic aspects that follow from identification of the driving mechanism for the pulsation of β Cephei stars by an analysis of the well-observed star δ Ceti. Ground-based photometric and ultraviolet IUE spectro-photometric observations were used. We find that the stellar model which fits the observed frequency of oscillation and nona…
A 3D Simulation of Intensities along Ulusses' Trajectory
Wibberenz, G.; Heber, B.; Burger, R. A. +1 more