Search Publications
Detection of Bernstein wave forbidden bands in the Jovian magnetosphere: A new way to measure the electron density
Forsyth, R. J.; Moncuquet, Michel; Meyer-Vernet, Nicole +2 more
We analyze the power spectra measured by the radio receiver of the Unified Radio and Plasma Wave experiment on Ulysses during its passage through the Jovian inner magnetosphere from ~9RJ in the outskirts of the Io plasma torus to ~13RJ near the plasma sheet. Below the plasma frequency fp, these spectra are weakly b…
Radial velocities and iron abundances of field RR Lyraes. II.
Garrido, R.; Solano, E.; Barnes, T. G. +1 more
This is the second of the papers devoted to derive radial velocities and iron abundances of field RR Lyraes observed by HIPPARCOS. Our abundances show good agreement with those in the literature obtained both from photometric (Delta S index) and spectroscopic methods. Binary candidates and stars misclassified as RR Lyraes in the original HIPPARCOS…
Is the geoeffectiveness of the 6 January 1997 CME predictable from solar observations?
Hoeksema, J. T.; Zhao, X. P.
We present a prediction scheme for specifying the duration and maximum strength of the southward IMF within a magnetic cloud from observations of the disappearing filament associated with the coronal mass ejection and the photospheric magnetic field made near the filament disappearing. Using this scheme we were able to predict that the Earth direc…
Charge Transfer between Neutral Atoms and Highly Ionized Species: Implications for ISO Observations
Korista, K. T.; Ferland, G. J.; Dalgarno, A. +1 more
We estimate rate coefficients for charge transfer between neutral hydrogen and helium and moderately to highly ionized heavy elements. Although charge transfer does not have much influence on hot collisionally ionized plasmas, its effects on photoionized plasmas can be profound. We present several photoionization models that illustrate the signifi…
Detection of Self-reversed Lyα Lines from the Jovian Aurorae with the Hubble Space Telescope
Ballester, Gilda E.; Prangé, Renée; Clarke, John T. +5 more
We present Lyα profiles taken at high spectral resolution (~70 mÅ) in the Jovian aurorae, using the Goddard High-Resolution Spectrograph aboard the Hubble Space Telescope. They exhibit a strong central reversal, reminiscent of solar and stellar spectra. This effect was predicted by models as a consequence of radiative transfer effects on photons e…
On the history of star formation in the bar of the Large Magellanic Cloud.
Gustafsson, B.; Ardeberg, A.; Linde, P. +1 more
With the HST PC and uvby photometry, we investigate evolutionary signatures in a field in the centre of the LMC Bar. Field stars close to the turn off point in the HR diagram are used for a study of ages and evolution of the stellar populations dominating the Bar as well as for determination of the abundance of heavy elements. Including fainter st…
Origins of the first-order anisotropy of ∼ 1 MeV protons in the Jovian magnetosphere during the Ulysses flyby: flux gradients and plasma flows
Balogh, A.; Forsyth, R. J.; Dunlop, M. W. +4 more
For zeroth-order distributions of energetic ions which are not too far from isotropy, the field-perpendicular first-order anisotropy results principally from the E × B plasma flow transverse to the magnetic field, and from spatial gradients in the ion flux. A technique is presented which separates these sources of anisotropy by examining their dep…
UIT: Ultraviolet Observations of the Small Magellanic Cloud
Parker, Joel Wm.; O'Connell, R. W.; Bohlin, R. C. +9 more
A mosaic of four UIT far-UV (FUV) (lambda_ {eff} = 1620 Angstroms) images, with derived stellar and HII region photometry, is presented for most of the Bar of the SMC. The UV morphology of the SMC's Bar shows that recent star formation there has left striking features including: a) four concentrations of UV-bright stars spread from northeast to so…
Bow shock analysis at comets Halley and Grigg-Skjellerup
Coates, A. J.; Neubauer, F. M.; Mazelle, C.
The interaction of an active comet with the solar wind is effected by the pickup of heavy cometary ions over extended regions of space. It was predicted before any spacecraft encounters with comets that a bow shock would form at a critical point in the mass-loaded flow. Here we present an analysis of the results from Giotto's encounters of comets …
Laboratory Identification of Temperature Diagnostic Si VII and S IX Lines Present in the Solar Coronal Spectra Measured by SUMER/SOHO
Schühle, U.; Feldman, U.; Laming, J. M. +3 more
The solar coronal spectrum between 500 and 1610 Å and at a height of 21,000 km above the west equatorial limb has recently been recorded by the SUMER instrument on SOHO. Using laboratory spectra obtained with the beam-foil technique, we report the identification of 32 lines observed in this spectrum as 2s22p33s-2s2…