Search Publications
Coronal hole diagnostics out to 8Rsun
Doyle, J. G.; Teriaca, L.; Banerjee, D.
The Si viii line width measurements and N_e estimates based on SUMER observations are combined with LASCO and UVCS output to provide an overview of its variations with height above a polar coronal hole. From the combined dataset we find a radial dependence of the electron density, in the range 1-2 Rsun as r(-8) , from 2 to 4 Rsun
The Eagle Nebula's fingers - pointers to the earliest stages of star formation?
Pilbratt, G. L.; White, G. J.; Holland, W. S. +14 more
Molecular line, millimetre/submillimetre continuum, and mid-IR observations are reported of the opaque fingers which cross the Eagle Nebula. The fingers are surprisingly warm when viewed in the CO J= 3-2 lines, with kinetic temperatures approaching 60 K, although the lines are relatively narrow. Most of the mass in the fingers is concentrated in c…
The composition and nature of the dust shell surrounding the binary AFGL 4106
Waters, L. B. F. M.; van Loon, J. Th.; Henning, Th. +8 more
We present infrared spectroscopy and imaging of AFGL 4106. The 2.4-5 mu m ISO-SWS spectrum reveals the presence of a cool, luminous star (Teff ~ 3750 K) in addition to an almost equally luminous F star (Teff ~ 7250 K). The 5-195 mu m SWS and LWS spectra are dominated by strong emission from circumstellar dust. We find that th…
3-D magnetic configurations supporting prominences. III. Evolution of fine structures observed in a filament channel
van Driel-Gesztelyi, L.; Aulanier, G.; Schmieder, B. +3 more
On September 25() th 1996, a quiescent filament located near the center disc (S2, E5) was observed on the German VTT (Tenerife) with the MSDP instrument, in the Hα line center and wings. SOHO/MDI line-of-sight magnetograms were co-aligned with the MSDP images, showing the position and evolution of the lateral feet of the filament in the vicinity o…
The delta Scuti star FG Virginis. IV. Mode identifications and pulsation modelling
Garrido, R.; Pamyatnykh, A. A.; Breger, M. +1 more
This paper examines the mode identification and presents pulsation models for FG Vir, for which 24 frequencies have been detected. Histograms of the frequency spacings show peaks which are identified with adjacent radial orders and rotational splitting. Pulsational l values are deduced for eight modes by comparing the observed photometric phase la…
Detection of moving groups among early type stars
Figueras, F.; Torra, J.; Chen, B. +1 more
Our procedure to detect moving groups in the solar neighbourhood \cite{chen} in the four-dimensional space of the stellar velocity components and age has been improved. The method, which takes advantadge of non-parametric estimators of density distribution to avoid any a priori knowledge of the kinematic properties of these stellar groups, now inc…
Self-consistent Alfvén-wave transmission and test-particle acceleration at parallel shocks
Vainio, R.; Schlickeiser, R.
The transmission of Alfvén waves at parallel shocks is treated self-consistently, i.e., taking the pressure and energy flux exerted by the waves into account when determining the shock's gas compression ratio. The resulting test-particle acceleration and transport parameters at the shock are shown to be functions of five parameters: the Alfvénic M…
Lithium in population I subgiants
Pasquini, L.; Pallavicini, R.; Randich, S. +2 more
We present a lithium survey for a sample of 91 Pop. I stars. JHKL photometry was also obtained for 61 stars in the sample. Besides Li abundances, [Fe/H] values were derived. Thanks to Hipparcos parallaxes, we could infer absolute V magnitudes for our sample stars and were able to place them on the color-magnitude diagram, which allowed us to const…
Detection of HD in the atmospheres of Uranus and Neptune: a new determination of the D/H ratio
de Graauw, Th.; Lellouch, E.; Feuchtgruber, H. +3 more
Observations with the Short Wavelength Spectrometer (SWS) onboard the Infrared Space Observatory (ISO) have led to the first unambiguous detection of HD in the atmospheres of Uranus and Neptune, from its R(2) rotational line at 37.7 mu m. Using S(0) and S(1) quadrupolar lines of H_2 at 28.2 and 17.0 mu m as atmospheric thermometers, we derive D/H …
Selection of a sample of bright southern Slowly Pulsating B Stars for long-term photometric and spectroscopic monitoring
De Ridder, J.; Aerts, C.; Cuypers, J. +7 more
The photometric experiment on Hipparcos has led to the discovery of, among other types of variables, a large amount of new Slowly Pulsating B Stars. We have selected twelve bright southern stars of this sample, together with five previously known Slowly Pulsating B Stars, for spectroscopic and photometric monitoring. These seventeen stars have spe…