Search Publications
XMM-Newton observation of the Tycho supernova remnant
Audard, M.; Ballet, J.; Decourchelle, A. +6 more
We present the observation of the Tycho supernova remnant obtained with the EPIC and RGS instruments onboard the XMM-Newton satellite. We compare images and azimuthally averaged radial profiles in emission lines from different elements (silicon and iron) and different transition lines of iron (Fe L and Fe K). While the Fe Xvii L line and Si Xiii K…
Prominence fine structures in a magnetic equilibrium: Two-dimensional models with multilevel radiative transfer
Heinzel, P.; Anzer, U.
In this paper we construct theoretical models for vertical prominence threads which are in magnetohydrostatic (MHS) equilibrium. These models are fully two-dimensional (2D) and take the form of vertically infinite threads hanging in a horizontal magnetic field. A typical example of such a 2D magnetic-dip structure is shown for the case when the ce…
Lithium abundances for 185 main-sequence stars: Galactic evolution and stellar depletion of lithium
Zhao, G.; Nissen, P. E.; Chen, Y. Q. +1 more
We present a survey of lithium abundances in 185 main-sequence field stars with 5600 <~ Teff <~ 6600 K and -1.4 <~ [Fe/H] <~ +0.2 based on new measurements of the equivalent width of the lambda 6708 Li I line in high-resolution spectra of 130 stars and a reanalysis of data for 55 stars from Lambert et al. (\cite{Lambert91}).…
The helium content and age of the Hyades:. Constraints from five binary systems and Hipparcos parallaxes
Lebreton, Y.; Fernandes, J.; Lejeune, T.
We compare the accurate empirical mass-luminosity (M-L) relation based on five Hyades binary systems to predictions of stellar models calculated with various input parameters (helium, metallicity and age) or physics (mixing-length ratio, model atmosphere, equation of state and microscopic diffusion). Models based on a helium content Y ~ 0.28 infer…
The obscured mid-infrared continuum of NGC 4418: A dust- and ice-enshrouded AGN
Lutz, D.; Tielens, A. G. G. M.; Moorwood, A. F. M. +2 more
We report the detection of absorption features in the 6-8 mu m region superimposed on a featureless mid-infrared continuum in NGC 4418. For several of these features this is the first detection in an external galaxy. We compare the absorption spectrum of NGC 4418 to that of embedded massive protostars and the Galactic centre, and attribute the abs…
Gas-grain chemical models of star-forming molecular clouds as constrained by ISO and SWAS observations
Ehrenfreund, P.; Charnley, S. B.; Rodgers, S. D.
We have investigated the gaseous and solid state molecular composition of dense interstellar material that periodically experiences processing in the shock waves associated with ongoing star formation. Our motivation is to confront these models with the stringent abundance constraints on CO2, H2O and O2, in both ga…
The NGC 4839 group falling into the Coma cluster observed by XMM-Newton
Aghanim, N.; Arnaud, M.; Molendi, S. +7 more
We present here the first analysis of the XMM-Newton EPIC-MOS data of the galaxy group around
The M 31 double nucleus probed with OASIS. A natural vec m = 1 mode?
Combes, F.; Copin, Y.; Emsellem, E. +3 more
We present observations with the adaptive optics assisted integral field spectrograph OASIS of the M 31 double nucleus in the spectral domain around the Calcium triplet at a spatial resolution better than 0farcs5 FWHM. These data are used to derive the two-dimensional stellar kinematics within the central 2 arcsec. Archival WFPC2/HST images in the…
The ISO-SWS spectrum of planetary nebula NGC 7027
Pottasch, S. R.; Beintema, D. A.; Bernard Salas, J. +1 more
We present the infrared spectrum of the planetary nebula
New light on the X-ray spectrum of the Crab Nebula
Warwick, R. S.; Aschenbach, B.; Becker, W. +5 more
XMM-Newton observations of the Crab provide new information on its integrated X-ray spectrum and the variation of the spectral form across the nebula. The Crab pulsar and its surrounding torus exhibit the hardest spectra with power-law indices of Gamma = 1.6 and 1.8. The jet and outer reaches of the nebula are significantly softer with Gamma = 2.1…