Search Publications
X-ray, UV, optical and radio observations of the visual binary 53 AQR
Pasquini, L.; Monsignori-Fossi, B. C.; Pallavicini, R. +1 more
The authors present optical (ESO), ultraviolet (IUE), X-ray (EXOSAT) and radio (VLA) observations of the visual binary 53 Aquarii. They show that the two components of the system can be used to infer the properties of the Sun at a much earlier epoch.
Coronal models of late-type stars observed with EXOSAT
Monsignori-Fossi, B. C.; Landini, M.; Pallavicini, R. +1 more
Differential emission measure distributions for transition region and corona able to reproduce X-ray and UV emission are investigated. The EXOSAT, EINSTEIN and IUE data for the solar type star K Cet are analyzed. A multitemperature differential emission measure distribution gives a satisfactory fit of the data.
IUE observations of neutral hydrogen and deuterium in the local interstellar medium.
Moos, H. W.; Murthy, J.; Linsky, J. L. +4 more
Small-aperture, high-dispersion IUE spectra have been obtained of seven late-type stars that, in general, confirm previous Copernicus results concerning the distribution of hydrogen and deuterium in the local interstellar medium. In addition, the IUE Ly α spectra of Altair, and of the α Cen components, suggest that multiple velocity components exi…
Coronal X-ray temperatures from Einstein and EXOSAT observations
Schmitt, J. H. M. M.; Monsignori-Fossi, B. C.; Pallavicini, R. +1 more
Spectral analysis of coronal X-ray emission from stars observed with both the Einstein and EXOSAT Observatories is presented. Using computer codes developed by Raymond and Smith /1/ and Landini and Fossi /2/ to calculate the X-ray emission from optically thin plasma in collisional equilibrium we find that the derived coronal parameters depend only…
Comet plasma tail formation - Giotto observations
Winningham, J. D.; Thomsen, M.; Borg, H. +8 more
The process of mass loading of the solar wind by cometary ions, which forms comet tails, has been observed throughout the coma of comet Halley. Three distinct regimes were found where the nature of the energy and momentum coupling between solar wind and cometary ions is different. Outside the bow shock, where there is little angular scattering of …
Extraterrestrial material analysis: Achievements and future opportunities for laboratory analysis in NASA and ESA planetary programmes
McDonnell, J. A. M.
Achievements in the understanding of the nature and distribution of extraterrestrial material recovered from space missions and stratospheric collection of ``Brownlee particles'' are examined in the context of the analytical techniques which have been applied to their study. A very wide range of powerful tools and techniques is now available for t…
Upper limits to ultraviolet line emission in fully convective M-dwarfs
Moreno, H.; Ambruster, C. W.; Kunkel, W. E. +1 more
Theoretical stellar structure models find that stars later than ~dM3 are fully convective. It is widely believed that this should result in reduced non-radiative heating and activity levels, however, the observational evidence is sparse and somewhat contradictory. In order to expand the number of atmospheric diagnostics for these stars, we have ob…
UV spectra of late-type stars and of representative solar features
Pallavicini, R.; Cerruti Sola, M.; Cheng, C. C.
The authors compare low-resolution short-wavelength IUE spectra of solar-type stars with high-resolution spatially-resolved Skylab spectra of individual solar features (quiet region, plage, flare). The comparison is used to obtain insights into the magnetic activity of stars.