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CCD photometry of the δ-Scuti star κ^2^ Bootis.
Kjeldsen, H.; Hjorth, J.; Thomsen, B. +4 more
CCD time-series differential photometry of the binary star κBoo has been carried out from a small in town situated telescope. One component of the system is known to be a δ-Scuti pulsator. Due to the high S/N data, four frequencies have been detected even though the window function is quite complicated. A search for a standard model that fits all …
The structure and evolution of the Nova V1974 Cygni shell from HST observations.
Paresce, F.; Livio, M.; Korista, K. +1 more
The Faint Object Camera on the refurbished Hubble Space Telescope (HST) observed Nova Cygni 1992 (V1974 Cyg) on three separate occasions in the first five months of 1994 through a series of interference and narrow band filters sensitive to the emission lines of OIII, OII, Hβ, Lyman α, HeII, NeIII, NeV, MgII, and NIV. Two objective prism images in …
Discovery of two hot DO white dwarfs exhibiting ultrahigh-excitation absorption lines.
Rauch, T.; Werner, K.; Dreizler, S. +3 more
We report on the detection of two faint blue stars (HE0504-2408 and HS0713+3958) discovered by the Hamburg Schmidt surveys whose spectra are dominated by broad and shallow metal absorption lines from ultrahighly excited ionization stages (CV, CVI/NVI, NVII/OVII, OVIII, NeIX, NeX) with ionization energies ranging from 392eV to 1362eV. Detailed non-…
Fundamental parameters of Wolf-Rayet stars. IV. Weak-lined WNE stars.
Hillier, D. J.; Crowther, P. A.; Smith, L. J.
A detailed study of 3 `weak-lined' Galactic WN3-4 stars (WR46=HD104994, WR128=HD187282 and WR152=HD211564) has been carried out based on new ultraviolet, optical and infrared spectroscopy. Tailored analyses, using the WR standard model, allow determinations of stellar parameters and chemical abundances based on the observed hydrogen, helium, carbo…
β Pictoris: evidence of light variations.
Deleuil, M.; Ferlet, R.; Vidal-Madjar, A. +4 more
We have analyzed β Pictoris photometric measurements obtained from La Silla by the Geneva Observatory from 1975 to 1992. These data show evidence of variations in the brightness of the star, with no color dependency. Here, we demonstrate that the light variations are present on long as well as on short time scales. On a long time scale, we show th…
Discovery of a galactic supersoft binary X-ray source.
Burwitz, V.; Beuermann, K.; de Martino, D. +10 more
We report the discovery of the galactic very soft ('supersoft') X-ray source RXJ0019.8+2156 and its 12.2mag optical counterpart. The system displays quasi-sinusoidal modulations of the optical, UV, and X-ray light curves as well as regular radial-velocity variations with a 15.85 hour period which we interpret as the binary orbital period. The syst…
Gas and dust emission from a dusty porous comet.
Capaccioni, F.; Orosei, R.; Coradini, A. +5 more
A comet nucleus is a porous aggregate of ices and dust in which solar heating causes the sublimation of volatiles and the ejection of dust particles lifted by the flow of the escaping gases. We present a numerical model that solves the heat conduction and the gas diffusion equations throughout a porous comet nucleus made of H_2_O ice, CO_2_ ice an…
Detectability and incidence of E+A galaxies in the distant cluster Cl0939+472 (z=0.41).
Belloni, P.; Bruzual, A. G.; Thimm, G. J. +1 more
We present results of a study of E+A galaxies in the cluster Cl0939+472 (z=0.41). We have used a series of narrow-band filters (FWHM=~90-200A) covering the range from 3800 to 9200A, and broad band B, R, I filters to obtain low resolution spectra for all galaxies brighter than R=22.5mag in a 5x5' cluster field. Two of the narrow-band filters have b…
Fundamental parameters of Wolf-Rayet stars. V. The nature of the WN/C star WR 8.
Crowther, P. A.; Willis, A. J.; Smith, L. J.
A detailed study has been carried out on the Galactic WN/C star WR 8 (HD62910), based on ultraviolet, optical and infrared spectroscopy. Our standard model analysis allows a determination of its stellar parameters and chemical abundances of hydrogen, helium, carbon, nitrogen and oxygen. We find that the WN and WC spectral features are consistent w…
Possible detection of a diffuse interstellar cloud boundary. II. HST-GHRS observations of Sirius A.
Ferlet, R.; Vidal-Madjar, A.; Lallement, R. +2 more
We present HST-GHRS observations with the G160M grating in the HI Lyman α spectral range toward Sirius A and around the Civ 1550 A doublet toward three lines of sight of the local interstellar medium. The local interstellar cloud (LIC) in which the Sun is embedded and another cloud (BC) are detected toward Sirius A from high spectral resolution Mg…