Search Publications
The circumstellar dust shell of the post-AGB star HD 161796
Waters, L. B. F. M.; Dominik, C.; Barlow, M. J. +3 more
We have modeled the complete optical to millimeter spectrum of the Post-Asymptotic Giant Branch (Post-AGB) star HD 161796 and its circumstellar dust shell. A full 2-200 mu m spectrum taken with the Infrared Space Observatory was used to constrain the dust properties. A good fit is achieved using only 4 dust components: amorphous silicates, the cry…
Distinguishing Local and Global Influences on Galaxy Morphology: A Hubble Space Telescope Comparison of High and Low X-Ray Luminosity Clusters
Kneib, J. -P.; Smith, G. P.; Smail, Ian +6 more
We present a morphological analysis of 17 X-ray-selected clusters at z~0.25, imaged uniformly with the Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2). Eight of these clusters comprise a subsample selected for their low X-ray luminosities (<~1044 ergs s-1), called the low-LX sample. The remaining ni…
Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009
Martin, P. G.; Harrington, J. P.; Balick, B. +8 more
We present new Hubble Space Telescope (HST)/WFPC2 imagery and STIS long-slit spectroscopy of the planetary nebula NGC 7009. The primary goal was to obtain high spatial resolution of the intrinsic line ratio [OIII] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (tA…
ISOCAM observations of the Ursa Major cirrus:. Evidence for large abundance variations of small dust grains
Miville-Deschênes, M. -A.; Boulanger, F.; Falgarone, E. +1 more
We present mid-IR imaging observations of a high Galactic latitude cirrus obtained with the ISO camera ISOCAM at 6'' angular resolution. The observations were done with two filters LW2 (5-8.5 mu m) and LW3 (12-18 mu m) that measure respectively the aromatic carbon bands and the underlying continuum emission from small dust particles. Three 0.05 sq…
Testing the line-driven disc wind model: time-resolved ultraviolet spectroscopy of IX Vel and V3885Sgr
Knigge, C.; Long, K. S.; Proga, D. +2 more
To confront the predictions of the most recent line-driven disc wind models with observational evidence, we have obtained Hubble Space Telescope (HST ) STIS (1180-1700Å) echelle spectra of the nova-like variables IX Vel and V3885Sgr at three epochs. The targets were observed in time-tag mode for ~2000s on each occasion, allowing us to study the sp…
On the Temperature Structure of M87
Molendi, Silvano
We revisit the XMM-Newton observation of M87, focusing our attention on the temperature structure. We find that spectra for most regions of M87 can be adequately fitted by single-temperature models. Only in a few regions, which are cospatial with the east and southwest radio arms, do we find evidence of a second temperature. The cooler component (…
The mineral composition and spatial distribution of the dust ejecta of NGC 6302
Waters, L. B. F. M.; Molster, F. J.; Kemper, F. +1 more
We have analysed the full ISO spectrum of the planetary nebula
Statistics of galaxy warps in the HDF North and South
Battaner, E.; Combes, F.; Jiménez-Vicente, J. +1 more
We present a statistical study of the presence of galaxy warps in the Hubble deep fields. Among a complete sample of 45 edge-on galaxies above a diameter of 1\farcs3, we find 5 galaxies to be certainly warped and 6 galaxies as good candidates. In addition, 4 galaxies reveal a characteristic U-warp. Compared to statistical studies of local warps, a…
An inverse method to interpret colour-magnitude diagrams
Bienaymé, O.; Egret, D.; Vergely, J. -L. +1 more
An inverse method is developed to determine the star formation history, the age-metallicity relation, and the IMF slope from a colour-magnitude diagram. The method is applied to the Hipparcos HR diagram. We found that the thin disk of our Galaxy shows a peak of stellar formation 1.6 Gyr ago. The stars close to the Sun have a solar metallicity and …
The Huygens Probe: Science, Payload and Mission Overview
Matson, D. L.; Lebreton, J. -P.
Huygens is an entry probe designed to descend under parachute through the atmosphere of Titan, Saturn's largest moon, down to the surface. The main Huygens science mission phase occurs during the 2 21/2 hours parachute descent. Measurements will also be conducted during the 3 min entry and possibly up to about one hour on the surface if…