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Circumstellar gas and dust in 68 Ophiuchi (A0 IVe).
Waters, L. B. F. M.; Grady, C. A.; The, P. S. +10 more
We present photometry and spectroscopy of the A0IVe star 68 Ophiuchi, for which Vidal-Madjar et al. (1993) suspected the presence of a circumstellar disc of material similar to that found around β Pic. The UV and optical continuum agrees well with a Kurucz model with parameters that are consistent with the spectral type. 68 Oph is detected at 12 a…
Multiwavelength observations of the bright QSO HS 0624+6907.
Clavel, J.; Reimers, D.; Heber, U. +9 more
We present non-simultaneous multi-wavelength observations of the bright radio-quiet QSO HS 0624+6907 (V=14.2, z=0.37) discovered by the Hamburg Survey (Groote et al. 1989). HS 0624+6907 has a particularly strong UV-soft X-ray bump which turns over already at the shortest IUE wavelengths, and it has a steep (Photon index {GAMMA}=-2.9) soft X-ray sp…
Toward the HIPPARCOS link: astrometry of stars and extragalactic sources in the field of the spiral galaxy M51.
Brosche, P.; Odenkirchen, M.
We present absolute proper motions of 14 Hipparcos stars from ground based photographic astrometry in a 2x2deg field around the spiral galaxy Messier 51. These are part of a catalogue of 340 stars with B<=16, for which positions, proper motions, and B magnitudes have been derived from a series of 16 photographic plates. Due to large epoch diffe…
A method for solving the linearized Boltzmann equation for almost uniformly rotating stellar disks.
Dejonghe, H.; Vauterin, P.
We construct analytical phase-space solutions for perturbations of flat disks by performing a power series expansion for the radius and the velocity coordinates. We show that this approach translates into an elegant mathematical formulation which is easy to use for a wide variety of distribution functions, for as far as resonances do not play a ro…
The HIPPARCOS multiple stars: reduction methods and preliminary results.
Pannunzio, R.; Morbidelli, R.; Sarasso, M. +2 more
This paper presents the first results obtained on a sample of multiple stars observed by Hipparcos, by two independent reduction methods (the Global Fitting approach and the Scanning Angle Functions method) on the basis of the data collected during the first 30 months of the mission. The preliminary results on a set of 10 triple stars are shown an…
A spectroscopic study of the suspected chemically peculiar star HD210424.
Leone, F.; Manfre, M.; Catalano, F. A.
HD210424 is a suspected Chemically Peculiar star in The general catalogue of Ap and Am stars by Renson et al. (1991). To investigate if HD210424 is really a CP star, we obtained time-resolved high-resolution spectra of this star in the 482-513nm region. The Hbeta_ line can be matched by an ATLAS9 (Kurucz 1993) model with solar abundance…
High-resolution imaging of the gravitational lens candidate 1208+1011 with the Nordic Optical Telescope.
Grundahl, F.; Hjorth, J.; Nilsson, K. +1 more
The large-redshift (z=3.8) quasar 1208+1011 has recently been discovered to be a gravitational lens candidate with a separation of 0.47" between the two imaged components (A and B). NOT (Nordic Optical Telescope) and HST (Hubble Space Telescope) studies from 1992 probing primarily the continuum light show that the amplification of A relative to B …
Comparison of ground-based proper motions from meridian observations and Astrographic Catalogue plates with HIPPARCOS proper motions
Lindegren, L.; Bastian, U.; Crifo, F. +5 more
During the preparation of the Hipparcos Input Catalogue the Bordeaux automatic meridian circle has measured the positions of about 2800 stars in the declination zone -2degto +31deg. These stars concentrate mainly in the visual magnitude range 10mag to 11mag. In this zone the (x,y) measurements of all Astrographic Catalogue (AC) plates have been ne…