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The Far Ultraviolet Spectrum of the Be-Star Ax-Monocerotis
Danezis, E.; Laskarides, P. G.; Theodossiou, E.
In this paper we study the main features of the far UV spectrum of the binary star AX Mon, observed with the IUE satellite at phase 0.568. Ions indicating a large range of ionization stages, going fromCI,OI,NI toSIV,CIV,NV are present. The spectrum is dominated by shell absorption lines of FeII, FeIII, SiIII,CII, AlII, MgII and NiII. Two satellite…
Modern Photographic Catalogue Work - Aspects of Observing Techniques and Reduction Methods
de Vegt, Chr.
The consequent application of present optical technology for the construction of substantially improved instrumentation in photographic astrometry and the application of rigorous reduction techniques provide all means for the construction of new, global position catalogs with a precision of a few 0.01 arcsec. At the same time the limiting magnitud…
Objectives of ground-based astrometry after HIPPARCOS
Kovalevsky, J.
After a short summary of the results expected from the HIPPARCOS mission, the author gives several examples illustrating the needs that will arise afterwards in order to maintain the level of precision achieved and to extend it to many more objects. Three domains are particularly dealt with in this paper:The maintenance of the HIPPARCOS reference …
Doublet 2800 Mg II in close binary systems
Perez, M.; Gurzadian, G. A.
It is shown that the emission ultraviolet doublet 2800 MgII in radio stars, actually in close binary systems, do not have chromospheric origin, but is generated in the space between the components of the system, filled by clouds or streams of two types — emission (A) and absorption (B). It is shown also that the strongly deformed or distorted form…
Ultraviolet light curves of V535 Arae
Eaton, Joel A.
Observations of V535 Ara obtained with IUE define the light curve of this long-period W UMa binary in the ultraviolet and let us estimate its gravity darkening. This star was chosen as a contact binary near the high-Teff limit for convection. The ultraviolet colours and spectral type correspond to (B‑V)0=0.24, or A8V, and imp…
The Far Ultraviolet Spectrum of the 04V-F Star 9-SAGITTARII
Danezis, E.; Laskarides, P. G.; Theodossiou, E.
A detailed list of line identifications of the far UV spectrum of the O4V((f)) star 9 Sagittarii (HD 164794) in the wavelength range λλ1174-2000 Å is presented. The identification is based on two spectra recorded in 1981 (on 16 April—SWP 13729 and on 24 August—SWP 14805) by the International Ultraviolet Explorer (IUE). In the list many unclassifie…
Planetary Nebula with a Peculiar Spectrum in the Ultraviolet - CN:3-1
Gurzadian, G. A.; Terzian, Yervant; Egikian, A. G.
We have obtained IUE ultraviolet spectra of the low-excitation planetary nebula CN 3-1. The recordings show the well-known doublet 2800 MgII and resonance line 2852 MgI as strong absorption lines. We show that these lines cannot be of interstellar origin and that they may be formed in two envelopes surrounding the main nebula: in the transition zo…
Planetary nebula with a neutral envelope?
Gurzadian, G. A.; Terzian, Yervant; Egikian, A. G.
IUE ultraviolet spectral recording for a low excitating planetary nebula NGC 6369 is obtained. The very strong doublet 2800 MgII in emission as well as not less strong absorption line 2852 MgI are discovered in the spectrum of this nebula. It is shown that the resonance line 2852 MgI may originate only in a neutral envelope, around the nebula, con…
Pseudo Resonance Absorption Lines in Planetary Nebulae - Discovery
Gurzadyan, G. A.; Egikyan, A. G.
The possibility of the formation of pseudo-resonance absorption lines in planetary nebulae is predicted only theoretically. However, this has not been confirmed by direct observations. In the present article an attempt has been made to show, as a result of careful analysis of IUE spectral recordings for a group of planetary nebulae, that the exist…
An early TYCHO astrometric catalogue
Bastian, U.; Hog, E.; Egret, D. +2 more
The TICR catalogue is arevision of TIC, theTYCHO Input Catalogue, and will contain positions derived from the first 12 months of TYCHO observations. Its properties, its role in TYCHO data analysis, and other possible uses are discussed. Since TICR will list about 500 000 stars with a positional precision of 0."15 (rms) and since it should become a…