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Azimuthal structures in the wind and chromosphere of the Herbig AE star AB Aurigae. Results from the MUSICOS 1992 campaign.
Talavera, A.; Donati, J. -F.; Semel, M. +19 more
The observations of the MUSICOS 1992 campaign concerned three scientific programs, among which was the study of azimuthal structures in the wind and chromosphere of the pre-main sequence Herbig Ae star AB Aur. The He I 5876A line of AB Aur, which is formed in the expanding chromosphere of this star, most probably in the innermost parts of its wind…
Radial velocities and axial rotation for a sample of chemically peculiar stars.
Morrell, N.; Levato, H.; Grosso, M. +2 more
As part of a systematic project we have determined radial velocities and projected rotational velocities for a sample of 186 chemically peculiar stars which have been observed by the Hipparcos' satellite. The purpose is to provide necessary data to study the space velocities of peculiar stars.
Determination of interstellar helium parameters from the ULYSSES-NEUTRAL GAS experiment: Method of data analysis.
Rosenbauer, H.; Witte, M.; Banaszkiewicz, M.
The GAS instrument on board the ULYSSES spacecraft has, for the first time, measured directly the interstellar flux of helium atoms in the inner solar system. From the locally measured angular distribution of the flux, the task is to derive the five parameters of the Maxwellian distribution function: density, bulk velocity vector, and temperature …
Multi-colour photometric and spectroscopic monitoring of the WN5 star EZ Canis Majoris.
van der Hucht, K. A.; van Genderen, A. M.; Duijsens, M. F. J. +3 more
We present and analyse photometric and spectroscopic observations of the WN5 star EZ Canis Majoris obtained over a period of 7years. We discuss the changing light curve, the shift in phase of the maxima and point to flare type variability seen in one night. Small amplitude variations are reported in another night. We have investigated the change o…
X-ray map from the EXOSAT galactic plane survey and a direct demodulation technique.
Lu, F. J.; Li, T. P.; Page, C. G. +2 more
In 1984 the EXOSAT observatory scanned the galactic plane with its medium-energy array which had a spatial resolution of about 0.75deg. The data analysis used at that time was unable to resolve some of the more complex regions near the galactic centre. The direct demodulation method is a technique to solve the image reconstruction problem in high …
UvbyHbeta_ photometry of main sequence A type stars.
Jordi, C.; Figueras, F.; Torra, J. +1 more
We present Stroemgren uvby and Hbeta_ photometry for a set of 575 northern main sequence A type stars, most of them belonging to the Hipparcos Input Catalogue, with V from 5mag to 10mag and with known radial velocities. These observations enlarge the catalogue we began to compile some years ago to more than 1500 stars. Our catalogue inc…
Ultraviolet properties of early-type galaxies.
Alloin, D.; Pastoriza, M. G.; Bonatto, C. +1 more
We analyse the UV properties of early-type galaxies from their UV spectra in the IUE library, including both normal and active nuclei. We co-added the spectra, and hence the objects into groups of similar spectral properties in the UV, also taking into account their properties in the visible/near-infrared ranges. Although, owing to the presence of…
Source standards for the radiometric calibration of astronomical telescopes in the VUV spectral range.
Huber, M. C. E.; Hollandt, J.; Kuehne, M. +1 more
On the basis of a high-current hollow-cathode discharge we have developed two transfer source standards suitable for the radiometric calibration of vacuum ultraviolet (VUV) telescopes. The source standards are transportable and (in their current design) produce a collimated beam of 5 and 10mm diameter. By irradiating the entrance aperture of the t…
First Cycle 4 multiwavelength observations of the gamma-ray quasar PKS 0208-512.
Vestrand, W. T.; Sreekumar, P.; Kubo, H. +3 more
We present first results of CGRO Cycle 4 multiwavelength observations of the gamma-ray quasar PKS 0208-512. A bright, variable gamma-ray source, PKS 0208-512 has been detected numerous times by the EGRET experiment aboard the CGRO, possessing one of the hardest spectra observed to date. The recent COMPTEL observations of Blom et al. (1995A&A..…
Probable detection of high-energy gamma-ray emission from OJ 287 during a major optical flare.
Shrader, C. R.; Hartman, R. C.; Webb, J. R.
We observed the BL Lac object OJ 287 with the CGRO/EGRET instrument as a target of opportunity triggered by an outburst in its visual intensity. OJ 287 is well known as a high-amplitude variable in the optical and radio domain, and recurrent outburst behavior at nominal 11.6-year intervals have led to speculation that there may be some determinist…