Search Publications
3D Coronal magnetic field from vector magnetograms: non-constant-alpha force-free configuration of the active region NOAA 8151
Amari, T.; Régnier, S.; Kersalé, E.
The Active Region 8151 (AR 8151) observed in February 1998 is the site of an eruptive event associated with a filament and a S-shaped structure, and producing a slow Coronal Mass Ejection (CME). In order to determine how the CME occurs, we compute the 3D coronal magnetic field and we derive some relevant parameters such as the free magnetic energy…
Dust depletion and abundance pattern in damped Lyalpha systems: A sample of Mn and Ti abundances at z < 2.2
Petitjean, P.; Bergeron, J.; Ledoux, C.
We analyse a sample of 24 damped Lyman-alpha (DLA)/moderate DLA systems at intermediate redshifts, 0.3<zabs<2.2, all with measurement of the weak Mn II absorption lines, to investigate which elemental ratios could possibly be used as tracers of either dust depletion or nucleosynthesis effects. We applied a component-by-component a…
Ice features in the mid-IR spectra of galactic nuclei
Lutz, D.; Tielens, A. G. G. M.; Moorwood, A. F. M. +3 more
Mid infrared spectra provide a powerful probe of the conditions in dusty galactic nuclei. They variously contain emission features associated with star forming regions and absorptions by circumnuclear silicate dust plus ices in cold molecular cloud material. Here we report the detection of 6-8 mu m water ice absorption in 18 galaxies observed by I…
On Be star candidates and possible blue pre-main sequence objects in the Small Magellanic Cloud
Mennickent, R. E.; Gieren, W.; Pietrzyński, G. +1 more
Recently the OGLE experiment has provided accurate light curves and colours for about 2 millions stars in the Small Magellanic Cloud. We have examined this database for its content of Be stars, applying some selection criteria, and we have found a sample of ~ 1000 candidates. Some of these stars show beautiful light curves with amazing variations …
Discovery of X-ray emission from the protostellar jet L1551 IRS5 (HH 154)
Micela, G.; Favata, F.; Sciortino, S. +2 more
We have for the first time detected X-ray emission associated with a protostellar jet, on the jet emanating from the L1551 IRS5 protostar. The IRS5 protostar is hidden behind a very large absorbing column density, making the direct observation of the jet's emission possible. The observed X-ray emission is likely associated with the shock ``working…
Dust and the spectral energy distribution of the OH/IR star OH 127.8+0.0: Evidence for circumstellar metallic iron
Waters, L. B. F. M.; de Koter, A.; Tielens, A. G. G. M. +2 more
We present a fit to the spectral energy distribution of
Nanodiamonds around HD 97048 and Elias 1
Tielens, A. G. G. M.; Waelkens, C.; Van Kerckhoven, C.
We present an analysis of ISO-SWS observations of the Herbig Ae/Be stars HD 97048 and Elias 1. Besides the well-known family of IR emission bands at 3.3, 6.2, ``7.7'', 8.6 and 11.2 mu m these objects show strong, peculiar emission features at 3.43 and 3.53 mu m. The latter two features show pronounced substructure which is very similar in the two …
The origin of the young stellar population in the solar neighborhood -- A link to the formation of the Local Bubble?
Breitschwerdt, D.; Berghöfer, T. W.
We have analyzed the trajectories of moving stellar groups in the solar neighborhood in an attempt to estimate the number of supernova explosions in our local environment during the past 20 million years. Using Hipparcos stellar distances and the results of kinematical analyses by Asiain et al. (\cite{Asiain1999a}a) on the Pleiades moving groups, …
An optical time-delay for the lensed BAL quasar HE 2149-2745
Kneib, J. -P.; Magain, P.; Lidman, C. +11 more
We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE 2149-2745. The data, obtained with the 1.5 m Danish Telescope (ESO-La Silla) between October 1998 and December 2000, are the first from a long-term project aimed at monitoring selected lensed quasars in the Southern Hemisphere. A time delay of 103+/-12 days is…
The magnetic nature of wide EUV filament channels and their role in the mass loading of CMEs
Aulanier, G.; Schmieder, B.
Previous works have shown that dark and wide EUV filament channels observed at lambda < 912 Å, are due to absorption of EUV lines in cool plasma condensations that are not observed in Hα . We extend this interpretation and we address the issue of the possible injection of their mass into CMEs, through the magneto-hydrostatic modeling in 3D of o…