Search Publications
The acceleration of slow coronal mass ejections in the high-speed solar wind
Riley, Pete; Gosling, J. T.
Using a one-dimensional hydrodynamic code we have simulated the radial evolution of heliospheric disturbances produced by slow coronal mass ejections (CMEs) embedded in much faster leading and trailing ambient solar wind. We find that pressure gradients induced by initial speed differences between slow CMEs and faster ambient wind can produce larg…
Corona(e) of AR Lacertae. II. The Spatial Structure
White, N. E.; Singh, K. P.; Siarkowski, M. +2 more
The X-ray light curves in the 0.4-1.5 keV and 2-7 keV bands of the RS CVn binary AR Lacertae observed on 1993 June 1-3 over one full orbital cycle with the ASCA satellite have been used to map the spatial structure of AR Lac's coronae. We find that both stars are X-ray active, that the corona of the K-type secondary star appears to be hotter than …
The cooling of the white dwarf in VW Hyi.
Gänsicke, B. T.; Beuermann, K.
We present an analysis of the post-outburst evolution of VW Hyi based on the available IUE archive data. The spectrum closest to the previous outburst (~0.5days) shows a non-negligible contribution of a disc remnant while the white dwarf (WD) dominates the later observations. Following an outburst, the accretion-heated WD cools exponentially to a …
Mid-Infrared spectrum of the zodiacal light.
Cesarsky, C.; Perault, M.; Boulanger, F. +10 more
Using the mid-infrared camera on the Infrared Space Observatory (ISO), the spectrum of a relatively empty piece of sky, dominated by zodiacal light, was measured from 5 to 16.5µm wavelength. The spectrum has no spectral features brighter than 15% of a blackbody fit to entire spectrum; the temperature of the fit is 261.5+/-1.5K. No galactic o…
HIPPARCOS distances and mass limits for the planetary candidates: 47 Ursae Majoris, 70 Virginis, and 51 Pegasi
Evans, D. W.; Arenou, F.; Lindegren, L. +19 more
Distances to the recently-discovered planetary system candidates, 47 UMa, 70 Vir and 51 Peg, are presented, based on absolute trigonometric parallaxes from the global reduction of the ESA Hipparcos astrometry satellite data. Standard errors of the parallaxes are in the range 0.66-0.76mas (milliarcsec), with resulting distances accurate to around 1…
Optical Structure in the Abell 1795 Cluster Central Galaxy: Evidence for Stripping and Deflection of Radio Jets
Sarazin, Craig L.; McNamara, Brian R.; Jannuzi, Buell T. +2 more
We have obtained a deep U-band image of the central ~100 kpc of the Abell 1795 cluster central galaxy. This image shows several faint ( mu U ~ 23--24 mag arcsec-2), thin structures, of unknown origin, that extend between 20 and 70 kpc into the galaxy's halo. Some are located along filaments of nebular line emission. Two structures, detected in the…
The Cooling White Dwarf in VW Hydri after Normal Outburst and Superoutburst: HST Evidence of a Sustained Accretion Belt
Szkody, Paula; Sion, Edward M.; Hubeny, Ivan +2 more
Hubble Faint Object Spectrograph (FOS) observations of VW Hyi one day after the end of a normal dwarf nova outburst reveal a heated white dwarf with deep, broad Ly alpha , narrow metallic absorption features, and evidence of a hotter Keplerian-broadened component manifested in quiescence as a broad continuum hump. Our best reduced chi 2 fit to the…
Relations Between ISM Inside and Outside the Heliosphere
Lallement, R.
Thanks to remarkable new tools, such as the Goddard High Resolution Spectrograph (GHRS) on board the HST and the EUVE spectrometer on the interstellar side, and Ulysses particle detectors on the heliospheric side, it is possible now to begin to compare abundances and physical properties of the interstellar matter outside the heliosphere (from abso…
The underlying Parker spiral structure in the Ulysses magnetic field observations, 1990-1994
Balogh, A.; McComas, D. J.; Forsyth, R. J. +2 more
The fundamental aim of the Ulysses space mission is to extend our understanding of the heliosphere into three dimensions. By April 1994 the spacecraft had reached a heliographic latitude of 60°S. Hourly averages of the Ulysses heliospheric magnetic field observations have been analyzed to determine to what extent the underlying field direction wit…
Hubble Space Telescope Observations of the Gravitational Lens System B1422+231
Impey, C. D.; Browne, I. W. A.; Petry, C. E. +2 more
Hubble Space Telescope observations of the gravitational lens system B1422+231 are presented. The spectra of the four components are virtually identical, although there are differences among the Ly alpha emission-line equivalent widths that might be due to microlensing. There are also significant differences between the component flux density rati…