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Quantitative analysis of the FUV, UV and optical spectrum of the O3 star HD 93129A.
Butler, K.; Lennon, D. J.; Kudritzki, R. P. +6 more
A quantitative analysis of the extremely hot and massive galactic O3If^*^ supergiant HD 93129A is carried out using stellar wind and pseudo photospheric lines observed in the FUV, UV and optical spectrum together with hydrodynamical NLTE model atmospheres. The analysis in the FUV is combined with spectrum synthesis of the molecular and atomic/ioni…
White dwarfs observed by the HIPPARCOS satellite.
Koester, D.; Vauclair, G.; Schmidt, H. +1 more
The HIPPARCOS satellite has measured trigonometric parallaxes for 20 white dwarfs. With the exception of one each of the spectral types DZ, DC, DB, DQ, the majority are of spectral type DA. We compare the parallaxes with the most recent ground-based determinations. From a spectroscopic analysis of new optical observations we determine atmospheric …
Elemental abundances in normal late-B and HgMn stars from co-added IUE spectra V. Mercury.
Smith, K. C.
Atmospheric mercury abundances are derived for a sample of 40 main-sequence, late-B stars, of which 14 are classified normal, and 26 are known chemically peculiar stars of HgMn or related He-weak types. The observational material for this study comprises co-added, short-wavelength IUE spectra encompassing the HgII λ1942 resonance line, coupled wit…
Widespread water vapour absorption in SGR B2.
Clegg, P.; Caux, E.; Cernicharo, J. +6 more
We report the discovery of widespread water vapour absorption in the 2_12_-1_01_ 179.5µm transition toward the SgrB2 molecular cloud. The data were obtained with the Long Wavelength Spectrometer (LWS) on board the ISO satellite. A raster map centered on SgrB2 made with the LWS grating clearly shows the 179.5µm H_2_O line in absorption …
The expansion of the envelope of Nova V1974 Cygni and the distance problem.
Chochol, D.; Hric, L.; Pribulla, T. +3 more
Available optical and UV spectroscopic, HST and radio imaging observations of the Nova V1974 Cygni were used to derive a kinematic model of the expansion of the nova shell. The nova shell consists of two major components: an outer fast tenuous low-mass envelope and an inner slow main high-mass envelope. The outer envelope, detected spectroscopical…
The UV/X-ray emission of the symbiotic star AG Draconis during quiescence and the 1994/1995 outbursts.
Greiner, J.; Altamore, A.; Stencel, R. E. +4 more
We present the results of an extensive campaign of coordinated X-ray (ROSAT) and UV (IUE) observations of the symbiotic star AG Dra during a long period of quiescence followed recently by a remarkable phase of activity characterized by two optical outbursts. The major optical outburst in June 1994 and the secondary outburst in July 1995 were cover…
The broad line region of narrow-line Seyfert 1 galaxies.
Mas-Hesse, J. M.; Rodriguez-Pascual, P. M.; Santos-Lleo, M.
We have analyzed new and archival IUE observations of narrow-line Seyfert 1 galaxies (NLS1) in order to revise the ultraviolet (UV) properties of this sub-group of Active Galactic Nuclei (AGN). We have found broad wings in the strongest UV emission lines, ruling out the hypothesis that there is no broad line emission region in this type of objects…
The morphological segregation of galaxies in clusters. III. The distant cluster CL 0939+4713 (Abell 851).
Andreon, S.; Davoust, E.; Heim, T.
We have performed an isophotal analysis of galaxies in the distant (z=0.4) cluster Cl0939+4713 (Abell 851), using post-refurbished Hubble Space Telescope images. Morphological type estimates for the galaxies are given. A rigorous comparison of the properties of the types shows that early-type galaxies in Cl0939+4713 are, within the present statist…
Hot HB stars in globular clusters: physical parameters and consequences for theory III. NGC 6752 and its long blue vertical branch.
Heber, U.; Moehler, S.; Rupprecht, G.
We present spectroscopic analyses of 17 faint blue stars in the globular cluster NGC 6752, using optical and UV spectrophotometric data and intermediate resolution optical spectra. Effective temperatures, surface gravities, and helium abundances of the stars are determined and compared to theoretical predictions. All stars are helium deficient by …
Detection of [O I] 63µm in absorption toward SGR B2.
Prusti, T.; Liseau, R.; Burgdorf, M. +26 more
A high signal-to-noise 52-90µm spectrum is presented for the central part of the Sagittarius B2 complex. The data were obtained with the Long Wavelength Spectrometer on board the Infrared Space Observatory (ISO). The [O I] 63µm line is detected in absorption even at the grating spectral resolution of 0.29µm. A lower limit for the…