Search Publications
On the origin of the fast solar wind in polar coronal funnels
Mann, G.; Marsch, E.; Hackenberg, P.
Funnels are open magnetic structures connecting the chromosphere with the solar corona ( \cite{Axf97,Mar97,Hac99}). We investigate the stationary plasma flow out of funnels with a flux-tube model. The funnel area function is derived from an analytical 2-D magnetic field model. Since the funnel height is only approximately 15 Mm, the area function …
A spectroscopic study of field BHB star candidates
Cacciari, C.; Bragaglia, A.; Castelli, F. +3 more
New spectroscopic observations are presented for a sample of thirty-one blue horizontal branch (BHB) star candidates that are sufficiently nearby to have reliable proper motions. Comments are given on a further twenty-five stars that have previously been suggested as BHB star candidates but which were not included in our sample. Moderately high-re…
Structure and chemical composition of the silicate dust around OH/IR stars
Dartois, E.; Wiesemeyer, H.; Demyk, K. +2 more
Using a radiative transfer code we have studied the dust shells of the two OH/IR stars IRAS 17004-4119 (OH344.93) and IRAS 17411-3154 (OH357). The ISO-SWS spectra of both sources exhibit deep amorphous silicate absorption bands at 9.8 and 17.5 mu m together with crystalline silicate emission bands at 33.6, 40.5 and 43 mu m. In both sources the 9.8…
Low-frequency p- and g-mode solar oscillations
Provost, J.; Berthomieu, G.; Morel, P.
In order to help the detection and identification of low-frequency p- and g-modes in the solar spectrum observed by ground-based networks and SoHO experiments, we study the properties of low degree (l=0 - 6) low-frequency (100 - 2000 mu Hz) solar oscillations. The frequencies of p- and g-modes have been computed for a set of solar models with upda…
ISO Spectroscopy of the young bipolar nebulae S106 IR and Cep A East
Tielens, A. G. G. M.; van den Ancker, M. E.; Wesselius, P. R.
We present the results of ISO SWS and LWS grating scans towards the embedded Young Stellar Objects (YSOs) S106 IR and Cep A East. Emission from the pure rotational lines of H_2 and the infrared fine structure lines of [C ii], [O i], [S i], [Si ii] and [Fe ii], as well as absorption bands due to H_2O, CO and CO_2 ice were detected toward Cep A. In …
Multiwavelength observations of N 66 in the SMC: unveiling photodissociation interfaces and star formation
Boulanger, F.; Contursi, A.; Maoli, R. +5 more
We present new observations of the major star-forming region N 66 in the Small Magellanic Cloud and of its surroundings, which add to those presented in Contursi et al. (\cite{Contursi99}, Paper I). High-sensitivity CO observations allowed the detection of molecular gas associated with the H i I region, for which a high-resolution image in [O iii …
Evaluation of solar energetic Fe charge states: effect of proton-impact ionization
Torsti, J.; Kocharov, L.; Kovaltsov, G. A. +1 more
We present the energy-dependent rates of ionization and recombination of energetic Fe ions in solar coronal plasma for the energy range from 0.01 to above 100 MeV nucleon-1. For the > 0.1 MeV n-1 ions, the energy dependencies become essential for both ionization and recombination processes. Ionization of the Fe projectile …
The far-infrared emission of radio loud and radio quiet quasars
Wilkes, B. J.; Polletta, M.; Courvoisier, T. J. -L. +1 more
Continuum observations at radio, millimetre, infrared and soft X-ray energies are presented for a sample of 22 quasars, consisting of flat and steep spectrum radio loud, radio intermediate and radio quiet objects. The primary observational distinctions, among the different kinds of quasars in the radio and IR energy domains are studied using large…
The reality of old moving groups - the case of HR 1614. Age, metallicity, and a new extended sample
Holmberg, J.; Feltzing, S.
We prove the existence of the old and metal-rich moving group HR 1614. This is done using the new Hipparcos parallaxes in combination with metallicities derived from Strömgren photometry, supported by dynamical simulations of the evolution of old moving groups in the galactic potential. A new selection criterion for this moving group is presented …
The origin of silicate carbon stars: ISO/SWS observation of V778 Cygni
Waters, L. B. F. M.; Dominik, C.; Yamamura, I. +2 more
The origin of silicate carbon stars has been a mystery ever since their discovery. We discuss here a full grating spectrum between 2.4 and 45 mu m of the silicate carbon star