Search Publications
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…
Search of the latest non-astrometric Hipparcos stars in the HST guide-star catalogue
Crifo, F.; Grenon, M.; Jahreiss, H. +1 more
During the preparation of the Hipparcos Input Catalogue, about 800 Hipparcos stars remained without reliable positions or with questionable identifications. The Hubble Space Telescope Guide Star Catalogue group at the STScI in Baltimore provided charts (10×10 or 16×16 arcmin) showing all stars in the field down to the limiting magnitude of the GSC…
Optical positions of radiostars. III.
Costa, E.; Loyola, P.
Precise optical positions, relative to either the Perth 70 or the AGK3R catalog have been obtained for 44 radiostars proposed to the Hipparcos observing list. Precision levels between 0.17 and 0.28 arcsec were obtained.
TYCHO assessment
Hog, E.; Wicenec, A.
The photon counts from the HIPPARCOS star mapper contains significant photometric and astrometric information on at least 400 000 stars in the interval of magnitudes from B=2 to 11. Analysis of the first few weeks of data from this TYCHO experiment on-board the HIPPARCOS satellite has shown that the original expectations can be fulfilled with the …
White dwarfs
Barstow, M. A.
Astronomical observations at EUV (~100-1000Å) and FUV (~1000-2000Å) wavelengths have revolutionised our knowledge of white dwarfs and evolutionarily related objects such as subdwarfs and the nuclei of planetary nebulae. Data obtained principally with the IUE and EXOSAT observatories have revealed the presence of trace elements within white dwarf a…
The discovery of a hot companion to the K-type supergiant HD 4817.
Cassatella, A.; Smolinski, J.
The discovery, through observations with the International Ultraviolet Explorer, of a B5 main sequence companion to the cool supergiant star HD 4817 (K2Ib-II) is reported. The object might be a new member of the Zeta Aur class. The UV observations indicate that HD 4817 is quite heavily reddened (E/B - V/ = 0.52) and that its distance is 1030 +/-80…
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…
Hipparcos data reduction overview
Lindegren, L.
The Hipparcos satellite generates about 1011 bytes of scientific data per year. The determination of astrometric and photometric quantities for the observed objects is a large and complicated task. The complexity is largely due to the strong coupling between objects in widely different parts of the sky, superposed by means of the two-wa…
Determination of Absolute Proper-Motions for the Connection of the HIPPARCOS System with a Quasi-Inertial System and the Automation of Astrometric Measurements of Tautenburg Schmidt Plates
Scholz, R. D.