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Hot subluminous stars at high galactic latitudes. V. UV spectra of binary and peculiar hot subdwarf stars.
de Boer, K. S.; Heber, U.; Moehler, S. +2 more
UV spectra observed with the IUE satellite of hot subdwarfs showing peculiarities in optical spectra are presented. Most peculiarities can be explained by the presence of a cool companion star. Assuming that the UV region is not affected by a cool companion, the fluxes of the hot component of the binary stars are modelled in the UV using theoretic…
Chromospheric Models for ALTAIR (A7 IV--V)
Talavera, A.; Kondo, Y.; Bruhweiler, F. +5 more
The star, Altair (A7 IV-V), is clearly shown to have Lyman-alpha emission of chromospheric origin, while no evidence is found for the Mg II emission reported in previous investigations. We present non-Local Thermodymanic Equilibrium (non-LTE) semiempirical models incorporating partial redistribution of the chromosphere of Altair that reproduce the…
Discovery of three UV-bright z>2 quasars.
Reimers, D.; Hagen, H. -J.; Rodriguez-Pascual, P. +1 more
We report the discovery within the Hamburg quasar surveys and subsequent UV observations with IUE of 10 bright, high-redshift quasars. While 3 objects appear completely absorbed below 3200A, HS 1103+6416 (z=2.19), HS 1307+4716 (z=2.13), HE 1122-1649 (z=2.40), HE 1230-2347 (z=1.85), and HE 1211-1322 (z=1.12) have been detected with the IUE short wa…
Impulsive bursts of energetic particles in the high-latitude duskside magnetosphere of Jupiter
Cowley, S. W. H.; Simpson, J. A.; McKibben, R. B. +6 more
Recent studies using the entire set of proton and electron measurements of the cosmic and solar particle investigations (COSPIN) on Ulysses revealed that the impulsive, sometimes quasi-periodic bursts discovered during the Ulysses' pass through Jupiter's duskside magnetosphere consisted not only of relativistic electrons and radio wave emissions b…
Search for gravitational wave trains with the spacecraft ULYSSES.
Vecchio, A.; Comoretto, G.; Giampieri, G. +8 more
We report on the search for periodic gravitational wave in the mHz band conducted with the spacecraft ULYSSES. Gravitational wave signals generally provide information about the distance of the source; ULYSSES' data have a "ken" for each kind of source one looks for; for binaries the galactic centre is accessible to our experiment. The Neyman Pear…
MERLIN observations of bipolar outflow from HM Sagittae
Davis, R. J.; Eyres, S. P. S.; Bode, M. F. +4 more
MERLIN maps of HM Sagittae at 6-cm and 18-cm wavelengths are presented. At 6 cm, the inner nebula has been mapped at a resolution of 60 milli-arcsec (mas), revealing two parallel ridge structures to the north and south of a deep central minimum. In addition, these central features are surrounded by a complex, weak structure. The ridges and many of…
Solar wind double ion beams and the heliospheric current sheet
Balogh, A.; Goldstein, B. E.; Phillips, J. L. +2 more
Double ion beams are often observed in the solar wind, but little work has been done in relating these beams to structures within the solar wind. Double ion beams are observed as beams of a given ion species and charge state occurring at two different energies. We use the three-dimensional ion plasma instrument on board the Ulysses spacecraft to l…
A photometric and spectroscopic study of BG Canis Minoris.
Mukai, K.; de Martino, D.; Bonnet-Bidaud, J. M. +5 more
The photometric and spectroscopic analysis presented here has revealed new observational features in the Intermediate Polar BG CMi. We have found a strong variability of the dominant light pulsations, rotational (913s) and orbital (3.23hr), on a timescale of years. Variations in the amplitude of the spin pulsation with epoch generally appear to be…
A comparison of ground-based stellar positions and proper motions with provisional HIPPARCOS results
Lattanzi, M. G.; Lindegren, L.; Mignard, F. +9 more
Preliminary positions and proper motions derived from the first 30 months of the Hipparcos mission are compared with some of the best ground-based catalogues and optical measurements. Comparison with FK5 and PPM very clearly brings out the zonal and regional errors of these catalogues. The proper motion system of PPM is found to have magnitude dep…
Stellar-Wind Variability in IUE Spectra of 68 Cygni
Howarth, Ian D.; Smith, Keith C.
We construct an empirical noise model for fully processed high-resolution, short-wavelength IUE spectra which takes crude account of the spatial variations of the camera response as well as the ripple-correction factors. We use this model to examine the velocity range over which statistically significant variability can be detected in the UV P Cyg…