Search Publications
The strongly constrained interacting binary BY Crucis.
Mayor, M.; Waelkens, C.; Daems, K.
We discuss spectroscopic and photometric observations (UV to IR) of BY Crucis, a new bright member of the interacting binaries of the W Serpentis class. The orbital period is 106.4days, and the mass function amounts to 5.92Msun_. The primary is an early-F supergiant which fills its Roche lobe; the massive secondary is hidden inside a th…
Elemental abundances in the Hg-Mn star γ Corvi.
Houziaux, L.; Fremat, Y.
Spectral data obtained at ESO, Observatoire de Haute-Provence and with the IUE covering the 120-910nm spectral range allowed us to determine the abundances of 21 elements in the atmosphere of the moderately fast rotating Hg-Mn star γ Corvi. We find that helium, carbon, nitrogen, magnesium, aluminium, silicium, sulfur, chromium, iron and nickel are…
Using the Earth orientation parameters to link the HIPPARCOS and VLBI reference frames.
Pesek, I.; Vondrak, J.; Ron, C.
One of the methods, used to link the free Hipparcos reference system to the conventional extragalactic reference system, is the indirect method using the rapidly rotating terrestrial reference system as an intermediary. We solve the Earth orientation parameters, referred to the preliminary Hipparcos reference frame H37C, from the observations made…
The eclipsing AM Herculis binary V2301 Ophiuchi. I. ROSAT & IUE observations.
Burwitz, V.; Beuermann, K.; de Martino, D. +2 more
We present X-ray and UV observations of the unique eclipsing cataclysmic variable V2301 Oph (1H1752+081). The X-ray eclipse of the primary star is total and corresponds in phase with the optical eclipse of the white dwarf. The X-ray light curve shows a quasi-sinusoidal orbital ``hump'' typical of AM Her systems. The orbital phase at which the hump…
The de-censoring of the faint stars in TYCHO photometry.
Grenon, M.; Hog, E.; Halbwachs, J. L. +3 more
The Tycho catalogue provides astrometric and photometric data for more than 1 million stars. The derivation of the mean magnitudes of stars fainter than about 8mag required a dedicated treatment, in order to take into account the observations that were too faint for providing a measurable signal. This treatment, called "de-censoring", is based on …
Spectroscopic observations of the interacting binary BY Crucis.
Waelkens, C.; Daems, K.
We present multi-wavelength spectroscopic data of the 106 day period interacting binary BY Crucis (Daems et al., 1997A&A...317..823D). The system consist of an early F-type supergiant that fills its Roche lobe and a more massive companion, hidden in a thick accretion disc. In the far-UV spectra (from 1200Å to 1950Å), strong emission lines of h…
The Infrared Space Observatory (ISO) mission.
Kessler, M. F.; Clavel, J.; Taylor, B. G. +8 more
ESA's Infrared Space Observatory (ISO) is an astronomical satellite, operating at wavelengths from 2.5-240 µm. Essentially, ISO consists of a large cryostat which contained at launch about 2300 litres of superfluid helium to maintain the Ritchey-Chretien telescope, the scientific instruments and the optical baffles at temperatures of 2-8 K. …
Observing with the ISO Short-Wavelength Spectrometer.
Lutz, D.; Genzel, R.; Heras, A. M. +59 more
The Short-Wavelength Spectrometer (SWS) is one of the four instruments on-board ESA's Infrared Space Observatory (ISO), launched on November 17, 1995. The spectrometer covers the wavelength range of 2.38 to 45.2µm with a spectral resolution ranging from 1000 to 2000. By inserting Fabry-Perot filters the resolution can be enhanced by a factor…
O-star mass-loss and wind momentum rates in the Galaxy and the Magellanic Clouds Observations and theoretical predictions.
Lennon, D. J.; Herrero, A.; Pauldrach, A. W. A. +8 more
A new, very fast approximate method is presented to determine mass-loss rates of O-stars from Halpha_ line profiles. The method uses H and HeII departure coefficients from unified model atmospheres parametrized in a simple way as function of wind velocity together with photospheric NLTE line profiles as the inner boundary condition for …
ISOPHOT - capabilities and performance.
Telesco, C.; Lemke, D.; Schulz, B. +46 more
ISOPHOT covers the largest wavelength range on ISO from 2.5 to 240µm. Its scientific capabilities include multi-filter and multi-aperture photometry, polarimetry, imaging and spectrophotometry. All modes can optionally include a focal plane chopper. The backbone of the photometric calibration are internal standard sources checked against cel…