Search Publications
The AGN contribution to mid-infrared surveys. X-ray counterparts of the mid-IR sources in the Lockman Hole and HDF-N
Altieri, B.; Elbaz, D.; Franceschini, A. +5 more
We provide constraints on the AGN contribution to the mid-IR extragalactic background light from a correlation analysis of deep X-ray and mid-IR observations in two regions centred on the Lockman Hole and Hubble Deep Field North (HDF-N). The Lockman region, of more than 200 square arcminutes, was observed by ISOCAM and XMM-Newton to a depth of 0.3…
The carrier of the ``30'' mu m emission feature in evolved stars. A simple model using magnesium sulfide
Waters, L. B. F. M.; Hony, S.; Tielens, A. G. G. M.
We present 2-45 mu m spectra of a large sample of carbon-rich evolved stars in order to study the ``30'' mu m feature. We find the ``30'' mu m feature in a wide range of sources: low mass loss carbon stars, extreme carbon-stars, post-AGB objects and planetary nebulae. We extract the profiles from the sources by using a simple systematic approach t…
ISO spectroscopy of compact H II regions in the Galaxy. II. Ionization and elemental abundances
Kessler, M. F.; Morisset, C.; Schaerer, D. +9 more
Based on the ISO spectral catalogue of compact H II regions by \cite{peeters:catalogue}, we present a first analysis of the hydrogen recombination and atomic fine-structure lines originated in the ionized gas. The sample consists of 34 H II regions located at galactocentric distances between RGal,= 0 and 15 kpc. The SWS H I recombinatio…
Crystalline silicate dust around evolved stars. I. The sample stars
Waters, L. B. F. M.; Barlow, M. J.; Tielens, A. G. G. M. +1 more
This is the first paper in a series of three where we present the first comprehensive inventory of solid state emission bands observed in a sample of 17 oxygen-rich circumstellar dust shells surrounding evolved stars. The data were taken with the Short and Long Wavelength Spectrographs on board of the Infrared Space Observatory (ISO) and cover the…
Speckle interferometry of nearby multiple stars
Weigelt, G.; Hofmann, K. -H.; Schertl, D. +5 more
We present the results of diffraction-limited optical speckle interferometry and infrared bispectrum speckle interferometry of 111 double and 10 triple systems performed in 1998-1999 with the 6-m telescope of the Special Astrophysical Observatory in Zelenchuk. The observations concentrated on nearby close binaries discovered during the Hipparcos m…
X-ray observations of a large-scale solar coronal shock wave
Aurass, H.; Khan, J. I.
We report observations of a propagating disturbance in the solar corona observed in emission in soft X-ray images from the Yohkoh Soft X-ray Telescope (SXT). The disturbance was associated with a flare which began at about 09:04 UT on 1997 November 03. This flare was associated with a type II radio burst observed at decimetric-dekametric wavelengt…
Dynamical masses of young star clusters in NGC 4038/4039
Genzel, R.; Lehnert, M. D.; Mengel, S. +1 more
In order to estimate the masses of the compact, young star clusters in the merging galaxy pair, NGC 4038/4039 (``the Antennae''), we have obtained medium and high resolution spectroscopy using ISAAC on VLT-UT1 and UVES on VLT-UT2 of five such clusters. The velocity dispersions were estimated using the stellar absorption features of CO at 2.29 mu m…
Astrometric radial velocities. III. Hipparcos measurements of nearby star clusters and associations
Lindegren, Lennart; Madsen, Søren; Dravins, Dainis
Radial motions of stars in nearby moving clusters are determined from accurate proper motions and trigonometric parallaxes, without any use of spectroscopy. Assuming that cluster members share the same velocity vector (apart from a random dispersion), we apply a maximum-likelihood method on astrometric data from Hipparcos to compute radial and spa…
Flare waves observed in Helium I 10 830 Å. A link between Hα Moreton and EIT waves
Vršnak, B.; Hanslmeier, A.; Warmuth, A. +1 more
Three traveling disturbances recorded in the absorption line of Helium I at 10 830 Å, (He I), analogous to Hα Moreton waves, are analyzed. The morphology and kinematics of the wavefronts are described in detail. The He I wave appears as an expanding arc of increased absorption roughly corresponding to the Hα disturbance, although not as sharply de…
XMM-Newton observation of the distant (z=0.6}) galaxy cluster RX J1120.1+4318
Aghanim, N.; Arnaud, M.; Giard, M. +11 more
We report on a 20 ks XMM observation of the distant cluster RX J1120.1+4318, discovered at z=0.6 in the SHARC survey. The cluster has a regular spherical morphology, suggesting it is in a relaxed state. The combined fit of the EPIC/MOS&pn camera gives a cluster mean temperature of kT= 5.3+/-0.5 kev with an iron abundance of 0.47+/-0.19. The te…