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An atmospheric model for the ion cyclotron line of Geminga

Caraveo, P. A.; Bignami, G. F.; Mignani, R. P. +3 more

Recent optical/UV data of Geminga (Mignani et al. 1998) have strengthen the significance of the emission feature present over the thermal continuum best fitting the EUV/soft X-ray data. Here we present a phenomenological model interpreting the data in terms of an ion cyclotron feature, arising from a thin outer layer of hot plasma covering Geminga…

Modelling the Sun as an active star. I. A diagnosis of photometric starspot models

van Driel-Gesztelyi, L.; Oláh, K.; Kővári, Zs. +1 more

We provide a diagnosis of photometric starspot models through modelling active areas on the Sun using softwares originally written for starspot modelling. The data we used were one-dimensional measurements of the Sun in radio (10.7 cm, DRAO, Canada) and in soft X-rays (GOES satellites). In these wavelengths the response to magnetic activity result…

X-type interactions of loops in the flare of 25 September 1997

Falewicz, R.; Rudawy, P.

The evolution and properties of the GOES C7.2 class solar flare observed in the NOAA 8088 active region on 25 September 1997 were studied with data taken by the Wroclaw Large Coronagraph/MSDP in Hα, Yohkoh/SXT and GOES X-rays as well as SOHO/MDI magnetic and SOHO/EIT ultraviolet observations. The observed properties of the flare are consistent wit…

Energetic particles in the duskside Jovian magnetosphere

Woch, J.; Dougherty, M. K.; Keppler, E. +2 more

The paper provides a detailed description of energetic ion measurements from the Energetic PArticle Composition instrument (EPAC) and magnetic field measurements from the dual-technique magnetometer on board Ulysses made in the duskside Jovian magnetosphere after its Jupiter flyby on February 8, 1992. The Ulysses spacecraft performed these in situ…

Phobos Disk-Integrated Photometry: 1994-1997 HST Observations

Thomas, Peter C.; Wolff, Michael J.; Cantor, Bruce A. +2 more

A program of synoptic monitoring of Mars was carried out with the Hubble Space Telescope from August 8, 1994, through October 9, 1997, using the Wide Field Planetary Camera 2 (WFPC2). With the improved optics of the WFPC2 and the high angular resolution of the Planetary Camera (0.0442-0.0455 arcsec/pixel) we have been able to use these images to s…

Variations in total solar and spectral irradiance as measured by the VIRGO experiment on SOHO

Fröhlich, Claus; Wehrli, Christoph; Pap, Judit +3 more

The Variability IRradiance Gravity Oscillation (VIRGO) experiment on SOHO has been observing total solar and spectral irradiances at 402 nm (blue channel), 500 nm (green channel), and 862 nm (red channel) since January 1996. The VIRGO observations have shown that solar active regions influence both total and spectral irradiances in a similar fashi…

Spectral analysis of the magnetic field inside particle propagation channels detected by ULYSSES

Forsyth, R. J.; Lanzerotti, L. J.; Maclennan, C. G. +2 more

Prior studies have identified particle propagation channels in the interplanetary medium where nearly scatter-free propagation occurs. These channels have been identified to exist as far away from the Sun as ~ 4 AU. We report here a study that has examined, using spacecraft-based instrumentation, the nature of the fluctuations of the interplanetar…

The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity

Lund, Niels; Elgarøy, Øystein; Engvold, Oddbjørn

The Wilson-Bappu effect is investigated using accurate absolute magnitudes of 65 stars obtained through early release of data from the Hipparcos satellite together with MgII k line widths determined from high resolution spectra observed with the International Ultraviolet Explorer (IUE) observatory. Stars of spectral classes F, G, K and M and lumin…

Analysis of thick, non-planar boundaries using the discontinuity analyser

Dunlop, M. W.; Woodward, T. I.

The advent of missions comprised of phased arrays of spacecraft, with separation distances ranging down to at least mesoscales, provides the scientific community with an opportunity to accurately analyse the spatial and temporal dependencies of structures in space plasmas. Exploitation of the multi-point data sets, giving vastly more information t…

The Darkest Regions of Solar Polar Coronal Holes Observed by SUMER on SOHO

Wilhelm, Klaus