Search Publications
On the wavelength drift of spectral features from structured hot star winds
Hamann, W. -R.; Oskinova, L. M.; Brown, J. C. +1 more
Spectral lines formed in stellar winds from OB stars are observed to exhibit profile variations. Discrete Absorption Components (DACs) show a remarkably slow wavelength drift with time. In a straightforward interpretation, this is in sharp contradiction to the steep velocity law predicted by the radiation-driven wind theory, and by semi-empirical …
First XMM-Newton observations of a Cataclysmic Variable II: The X-ray spectrum of OY Car
Pandel, D.; Ramsay, G.; Mason, K. +6 more
We present XMM-Newton X-ray spectra of the disc accreting cataclysmic variable OY Car, which were obtained during the performance verification phase of the mission. These data were taken 4 days after a short outburst. In the EPIC spectra we find strong iron Kalpha emission with weaker iron Kbeta emission together with silicon and sulphur lines. Th…
Deep submillimeter images of NGC 7331; dust at the periphery of spiral disks
Bianchi, S.; Combes, F.; Lequeux, J. +3 more
We present deep 450 and 850 mu m SCUBA images of the nearby spiral galaxy NGC 7331. Using the submillimeter emissivity inferred from COBE observations of Milky Way dust, we convert our SCUBA images into maps of optical depth. The opacity derived in this way is quite low at the visible limit of NGC 7331 (tau B<= 0.22 at the R25
The B-type variable HD 131120 modelled by rotational modulation
Aerts, C.; Briquet, M.; De Cat, P. +1 more
We present ground-based multi-colour Geneva photometry and high-resolution spectra of the variable B-type star HD 131120. All sets of data reveal a monoperiodic star with a period of 1.569 days. We compare the variability of the star with a non-radial g-mode pulsation model and with a rotational modulation model. The latter model appears to be the…
HST/STIS spectroscopy of the exposed white dwarf in the short-period dwarf nova EK TrA
Gänsicke, B. T.; Szkody, P.; Hoard, D. W. +4 more
We present high resolution Hubble Space Telescope ultraviolet spectroscopy of the dwarf nova EK TrA obtained in deep quiescence. The Space Telescope Imaging Spectrograph data reveal the broad Lyalpha absorption profile typical of a moderately cool white dwarf, overlayed by numerous broad emission lines of He, C, N, and Si and by a number of narrow…
FIRBACK. II. Data reduction and calibration of the 170 µ m ISO deep cosmological survey
Dole, H.; Lagache, G.
We present the final reduction and calibration of the FIRBACK ISOPHOT data. FIRBACK is a deep cosmological survey performed at 170 mu m. This paper deals with the ISOPHOT C200 camera with the C160 filter. We review the whole data reduction process and compare our final calibration with DIRBE (for the extended emission) and IRAS (for point sources)…
Exploration of the BaSeL stellar library for 9 F-type stars COROT potential targets. Comparisons of fundamental stellar parameter determinations
Cuisinier, F.; Lignières, F.; Buser, R. +4 more
The Basel Stellar Library (BaSeL models) is constituted of the merging of various synthetic stellar spectra libraries, with the purpose of giving the most comprehensive coverage of stellar parameters. It has been corrected for systematic deviations detected in respect to UBVRIJHKLM photometry at solar metallicity, and can then be considered as the…
Ultraviolet spectra for lambda Boo (HD 125162) computed with H2 opacities and Lyman-alpha H-H and H-H+ opacities
Castelli, F.; Kurucz, R. L.
New opacity distribution functions (ODF) have been computed for use with the ATLAS9 model atmosphere code of Kurucz. One of the improvements upon the Kurucz (\cite{kur90}) ODFs is the addition to the line blanketing of the Lyman-alpha H-H and H-H+ quasi-molecular absorptions near 1600 Å and 1400 Å. New-ODF fluxes are expected to reprodu…
Binary systems with post-T Tauri secondaries
Gerbaldi, M.; Faraggiana, R.; Balin, N.
The identification of post-T Tauri (pTT) stars selected through spectroscopic criteria by Pallavicini et al. (\cite{Pallavicini92}) and by Martín et al. (1992) among the candidates belonging to visual binary systems is revisited in the present paper by studying their position in the HR diagram. These stars belong to the so-called Lindroos binary s…
A model for the origin of the anomalous and very bright UV lines of Fe II in gaseous condensations of the star η Carinae
Johansson, S.; Letokhov, V. S.
We present a qualitative physical model of the origin of two very bright UV lines of Fe II at 2507-2509 Å, present in high-resolution spectra of gaseous condensations (blobs) close to the central star of eta Carinae. The spectra have been obtained with the Hubble Space Telescope (HST). The model is based on a type of Bowen mechanism with selective…