Search Publications
Ephemerides of the 48 HIPPARCOS minor planets for the year 1992
Bec-Borsenberger, A.
To be observed by Hipparcos, the position of each object has to be known with an accuracy of 1 arcsecond and its magnitude with an accuracy of 0.5 mag. Therefore, the orbital elements of the 48 selected minor planets of the Hipparcos mission, have been improved in order to extrapolate their ephemerides with the accuracy required. Updated ephemerid…
Precise equatorial coordinates of double and multiple systems : an astronomical support to the HIPPARCOS mission.
Pannunzio, R.; Lattanzi, M. G.; Morbidelli, R. +3 more
Results are presented on determinations of precise positions (to the accuracy required for their possible inclusion in the Hipparcos Input Catalogue) of 623 double and multiple stars (126 of them newly discovered) from the measurement of 39 plates taken at the ESO and the Astronomical Observatory of Torino, obtained between 1984 and 1987. The tabl…
On zenith-distance variations of the Borowiec astrolabe
Lehmann, M.; Wiktorowski, J.
Systematic differences between zenith distances of two groups of stars observed successively during the same night occur in observations carried out with the Danjon Astrolabe in Borowiec. Four suggestions for the determination of an additional parameter correlated in the best way with the observed variations of zenith distance are made. The best c…
Determinations of the interstellar reddening toward Wolf-Rayet stars of the nitrogen sequence from observed UBV color indices.
Schmutz, W.; Vacca, W. D.
We demonstrate that continuum discontinuities, or "jumps", are present in the spectra of some Wolf-Rayet stars and that current models of Wolf-Rayet stars predict such jumps and provide good fits to the observed continua. Using a relation between the size of the He II (n = 4) jump at 3645 A and the intrinsic (b - v)_0_ color found from the model a…
High resolution observations of chromospheric lines in late-type dwarfs.
Houdebine, E. R.; Byrne, P. B.; Panagi, P. M.
High resolution H-alpha absorption- and emission-line profiles are reported for 11 stars of spectral types ranging from K5V to M3V, and the profiles of NaI(D), HeI(5876A), and CaII(IR) are given for portions of the sample. The observations were taken with the Qubes spectrograph, and the data are reduced by comparing the spectral data with observat…
The UV properties of normal galaxies. I. The IUE data.
Longo, G.; Capaccioli, M.; Ceriello, A.
As a first step toward a better understanding of the energy distribution of normal galaxies at wavelengths shorter than 3300 A, all IUE low resolution spectra of normal galaxies have been reduced to a photometric system consisting of seven intermediate-widths bands, five of which matching the ANS photometric system. Dereddened ultraviolet magnitud…
Short term H-alpha variations in two Herbig PMS stars : HR 5999 and HD 52721.
Catala, C.; The, P. S.; Tjin A Djie, H. R. E. +2 more
We present high spectral resolution observations of Hα as well as V photometry and IUE observations for two Herbig pre-main sequence stars, HR 5999 and HD 52721. These observations, performed in 1985, were aimed at studying short-term variations of the Hα line, within one night and from night to night. Hα spectra of comparison stars are also displ…
Photometric and spectroscopic studies of cool stars discovered in EXOSAT X-ray images. I. Time variability and spectral classification of eight southern stars.
Tagliaferri, G.; Pasquini, L.; Pallavicini, R. +4 more
As part of a larger program to study the optical properties of serendipitous Exosat sources, optical photometry and low-resolution spectroscopy are presented for eight southern stars which have been identified as optical counterparts of Exosat sources. X-ray flux variability has been detected for three of them. In all three cases the optical count…
Twelve years of IUE spectra of the interacting binary VV Cephei.
Stencel, R. E.; Neff, D. H.; Bauer, W. H.
All well-exposed high-resolution IUE spectra obtained of the eclipsing binary system VV Cephei (M2Iabep + B) are examined. High-temperature absorption features attributable to the hot companion were detected, indicating that the companion (or the inner regions of its accretion disk) are not as hot as a B1-B2 star. Doubling of Fe II (UV 1) lines, w…
Location and thickness of the nearest neutral gas cloud in the direction of Auriga-Perseus.
de Boer, K. S.; Lilienthal, D.
High dispersion IUE spectra of stars in the general direction of Auriga-Perseus show clear interstellar absorption lines whose strengths are used to derive information about the spatial distribution of the gas on the lines of sight. The distance to the nearest neutral cloud in this direction is about 50 pc; it has a depth of approximately 15 pc an…