Search Publications
A study of solar analogues in the ultraviolet.
Solano, E.; Wamsteker, W.; Fernley, J. +1 more
We have made a comparative study of the Sun and solar analogue stars using the published solar ultraviolet fluxes and IUE low dispersion spectra of the solar analogues. The Hyades dwarf HD 28099 (vB64) shows a flux excess below 2500A which is probably due to chromospheric activity since it is a relatively young star. HD 44594, 186408 (16CygA) and …
Faint Object Camera observations of complex nuclear structure in PKS 2158-380.
Boksenberg, A.; Blades, J. C.; Disney, M. J. +3 more
We present the results of Hubble Space Telescope observations of the nucleus of the narrow-line radio galaxy PKS 2158-380. Faint Object Camera images (taken before the December 1993 servicing mission) in bands centered near 3720A and 3420A show complex nuclear structure. The nucleus consists of three well resolved components of sizes ~0.3" (~0.28k…
Symmetry in discontinuity properties at the north and south heliographic poles: Ulysses.
Balogh, A.; Tsurutani, B. T.; Goldstein, B. E. +3 more
A study of directional discontinuities (DDs) that occurred during 4 days of the Ulysses north polar pass was conducted (461 directional discontinuities total) using magnetic field and plasma data. We find that the total number of directional discontinuities selected by the Tsurutani and Smith (1979) method are the same in the north and south polar…
The galactic warp in young stars proper motions.
Lattanzi, M. G.; Smart, R. L.
Using Monte Carlo simulations of the Galaxy parameters, we have investigated the expected effects of a galactic warp model on the proper motions of early type stars. The introduction of the warp into the Galaxy simulation appears very pronounced in galactic latitude proper motions, but unobservable in galactic longitude proper motions. The proper …
The quasi-parallel shock wave detected by ULYSSES on day 92:109.
Balogh, A.; Smith, E. J.; Phillips, J. L. +1 more
On day 92:109, at about 5.4 AU and 9° south, Ulysses detected a strong quasi-parallel shock wave leading an interaction region. We describe this singular event on different temporal scales, placing emphasis on the magnetic field observations. The solar wind preceding the shock presented very unusual long-lived conditions: for about one day the int…
Starburst activity in X-ray and FIR luminous galaxies: the case of NGC 4619 and IRAS 15564+6359.
Mas-Hesse, J. M.; Rodriguez-Pascual, P. M.; Cerviño, M. +1 more
We have analyzed the multiwavelength (soft X-rays to far infrared) energy distribution of IRAS 15564+6359 and NGC 4619, two galaxies previously not classified as active galaxies but found during the ROSAT All Sky Survey to be very luminous in the X-ray and far infrared (FIR) ranges. By comparison with population synthesis evolutionary models we ha…
Comparison of the Carlsberg optical reference frame with the International Celestial Reference Frame.
Fabricius, C.; Jones, D. H. P.; Morrison, L. V. +4 more
The optical positions of 63 extragalactic nebulae measured in the frame defined by the annual series of Carlsberg Meridian Catalogues Nos 1-8 are compared with their VLBI radio positions in the International Celestial Reference Frame. The differences between these radio and optical positions are interpreted as showing the global distortion of the …
First UV spectrum of the AM Herculis star RX J1940.1-1025.
Staubert, R.; Friedrich, S.; La Dous, C.
We present the first UV spectrum of the polar RX J1940.1-1025, taken with the IUE satellite in the wavelength range between 1190A to 1950A. The phase averaged spectrum shows strong emission lines of CIV (1550A), NV (1240A), SiIV (1397A) and HeII (1640A) which are typical for AM Her stars. The line ratios of NV/SiIV and NV/CIV, and the continuum fl…
Generation of plasma turbulence and radio emission at the front of interplanetary MHD shocks.
Ledenev, V. G.
Based on spectral observations of turbulence and radio emission in the interplanetary medium from the Ulysses spacecraft, we describe processes responsible for the formation of energetic particle fluxes, the generation of Langmuir and ion acoustic turbulence, and the radio emission at the front of a quasi-perpendicular MHD shock wave. It is shown …
Branches and loops in the X-Ray colour-colour diagram of Cygnus X-3.
van der Klis, M.; Smit, J. M.
We present an analysis of EXOSAT ME X-ray colour-colour diagrams of Cygnus X-3. Our sample contains all the Cygnus X-3 data collected during EXOSAT's operational life time and covers a total of 190 hours. The colour-colour diagrams display X-ray spectral variations with the 4.8 hour period and show the spectral distinction between the `high' and t…