Search Publications
X-type interactions of the loops in the flare of 25 September 1997 - Part II
Mandrini, C. H.; Siarkowski, M.; Falewicz, R. +1 more
The interaction of magnetic structures and the conversion of magnetic free energy into heating of the plasma and acceleration of particles are commonly accepted as the origin of solar flares. The 3-dimensional (3D) structure and evolution of the coronal magnetic field can be investigated indirectly by the analysis of the images of various loops fi…
A search for the optical counterpart to PSR B1821-24 in M 28
Golden, A.; Shearer, A.; Butler, R. F.
We have analysed archival HST/WFPC2 images in both the F555W & F814W bands of the core field of the globular cluster M 28 in an attempt to identify the optical counterpart of the magnetospherically active millisecond pulsar PSR B1821-24. Examination of the radio derived error circle yielded several potential candidates, down to a magnitude of …
Deep imaging of Q2112+059: A bright host galaxy but no DLA absorber
Møller, P.; Thomsen, B.; Fynbo, J. U.
In an ongoing programme aimed at studying galaxy counterparts of Damped Lyα Absorbers (DLAs) we have obtained high resolution deep I-band imaging data of the field around the zem = 0.457 BAL QSO Q2112+059. In the literature this QSO is listed to have a candidate DLA at zabs = 0.2039 along the line of sight. After subtraction …
Detection of arcs in Saturn's F ring during the 1995 Sun ring-plane crossing
Charnoz, S.; Brahic, A.; Ferrari, C. +3 more
Observations of the November 1995 Sun crossing of the Saturn's ring-plane made with the 3.6 m CFH telescope, using the UHAO adaptive optics system, are presented here. We report the detection of four arcs located in the vicinity of the F ring. They can be seen one day later in HST images. The combination of both data sets gives accurate determinat…
New determination of the solar apex
Duflot, M.; Burnage, R.; Fehrenbach, Ch.
Many studies recently have been performed to determine the velocity vector of the Sun, mainly using the latest data on proper motions and parallaxes given by the Hipparcos satellite. We wished to carry out a similar study using totally independent data: the numerous radial velocities (RV) obtained with the Fehrenbach Objective Prisms (PO). This me…
The effect of anisotropic gas pressure on Alfvén-wave transmission and test-particle acceleration at parallel shock waves
Vainio, R.; Schlickeiser, R.
Alfvén-wave transmission through a parallel shock in case of an anisotropic gas pressure (Pparallel!=q Pperpendicular to is considered from the point of view of test particle acceleration in such shock waves. Treating the shock's gas compression ratio and the firehose factor, phi =1-4pi (Pparallel-Pperpendicul…
Research Note The evolutionary status of the early-type binary HD 115071
Stickland, D. J.; Lloyd, C.
An analysis of the Hipparcos photometry of HD 115071 shows that it is an ellipsoidal variable with a period of 2.73126 days, twice that suggested previously. Modelling the light curve combined with the available radial velocities suggests that the more massive, hotter component is smaller and less luminous than the cooler component, which is proba…
Properties of EUV and X-ray emission in solar active regions
Klimchuk, J. A.; Harra, L. K.; Matthews, S. A.
Using observations from the Coronal Diagnostic Spectrometer (CDS) on SoHO and the Soft X-ray Telescope (SXT) on Yohkoh we investigate how the spatial properties of active region emission observed in the EUV and X-ray range varies with temperature. We examine the contrast per unit area of the EUV emission from a number of active regions, and employ…
Application of Fano profiles to asymmetric resonances in helioseismology
Boumier, P.; Gabriel, A. H.; Thiery, S. +1 more
Parallels are drawn between the asymmetric resonance profiles observed in global helioseismology and the Fano theory for autoionisation profiles in atomic spectroscopy. We show that the underlying physics of the interaction of a discrete resonance with a correlated continuum is common to both systems. The approximate formula normally used for fitt…
Infrared spectral classification of OB stars with ISO-SWS
Waters, L. B. F. M.; de Koter, A.; Zaal, P. A.
We present observations of the Bralpha , Brbeta and Pfalpha lines of 16 dwarf and (sub)giant stars in the spectral range O9-B3. The observations were done using the Short Wavelength Spectrometer on board the Infrared Space Observatory, and have a signal-to-noise of ~ 20 to > 150 and a resolving power varying from ~ 1400 to 2100. We compare the …